The common ostrich (''Struthio camelus''), or simply ostrich, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
flightless bird
Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the In ...
native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members of the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Struthio
Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are ...
'' in the
ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
order of birds. The other is the
Somali ostrich
The Somali ostrich (''Struthio molybdophanes''), also known as the blue-necked ostrich, is a large flightless bird native to the Horn of Africa. It is one of two living species of ostriches, the other being the common ostrich. It was also previo ...
(''Struthio molybdophanes''), which was recognized as a distinct species by
BirdLife International
BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...
in 2014 having been previously considered a distinctive subspecies of ostrich.
The common ostrich belongs to the
order
Order, ORDER or Orders may refer to:
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
* Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
Struthioniformes
Struthioniformes is an order of birds with only a single extant family, Struthionidae, containing the ostriches. Several other extinct families are known, spanning across the Northern Hemisphere, from the Early Eocene to the early Pliocene, includ ...
. Struthioniformes previously contained all the ratites, such as the
kiwis,
emu
The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus ''Dromaius''. The emu' ...
s,
rheas
The rheas ( ), also known as ñandus ( ) or South American ostriches, are large ratites (flightless birds without a keel on their sternum bone) in the order Rheiformes, native to South America, distantly related to the ostrich and emu. Most taxo ...
, and
cassowaries
Cassowaries ( tpi, muruk, id, kasuari) are flightless birds of the genus ''Casuarius'' in the order Casuariiformes. They are classified as ratites (flightless birds without a keel (bird anatomy), keel on their sternum bones) and are native t ...
. However, recent genetic analysis has found that the group is not monophyletic, as it is paraphyletic with respect to the
tinamou
Tinamous () form an order of birds called Tinamiformes (), comprising a single family called Tinamidae (), divided into two distinct subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" come ...
s, so the ostriches are now classified as the only members of the order.
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
studies have shown that it is the sister group to all other members of
Palaeognathae
Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contai ...
and thus the flighted tinamous are the sister group to the extinct
moa
Moa are extinct giant flightless birds native to New Zealand.
The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as
Kale moa and Moa Samoa.
Moa or MOA may also refer ...
.
It is distinctive in its appearance, with a long neck and legs, and can run for a long time at a speed of with short bursts up to about ,
the fastest land speed of any bird.
[ The common ostrich is the largest living species of bird and ]largest
Large means of great size.
Large may also refer to:
Mathematics
* Arbitrarily large, a phrase in mathematics
* Large cardinal, a property of certain transfinite numbers
* Large category, a category with a proper class of objects and morphisms (or ...
living dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
. It lays the largest eggs of any living bird (the extinct elephant bird
Elephant birds are members of the extinct ratite family Aepyornithidae, made up of flightless birds that once lived on the island of Madagascar. They are thought to have become extinct around 1000-1200 CE, probably as a result of human activity. ...
s of Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
and the giant moa
The giant moa (''Dinornis'') is an extinct genus of birds belonging to the moa family. As with other moa, it was a member of the order Dinornithiformes. It was endemic to New Zealand. Two species of ''Dinornis'' are considered valid, the Nort ...
of New Zealand laid larger eggs).
The common ostrich's diet consists mainly of plant matter, though it also eats invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s and small reptiles. It lives in nomadic groups of 5 to 50 birds. When threatened, the ostrich will either hide itself by lying flat against the ground or run away. If cornered, it can attack with a kick of its powerful legs. Mating patterns differ by geographical region, but territorial males fight for a harem of two to seven females.
The common ostrich is farmed
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...
around the world, particularly for its feathers, which are decorative and are also used as feather duster
A feather duster is a cleaning tool that is typically made from a wooden dowel handle onto which ostrich feathers are wound with a wire. The feathers are most often long. Some dusters have a retractable casing instead of a dowel handle and thes ...
s. Its skin is used for leather
Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, ...
products and its meat is marketed commercially, with its leanness a common marketing point.
Description
Common ostriches usually weigh from , or as much as one to two adult humans. The Masai ostrich
The Masai ostrich (''Struthio camelus massaicus''), also known as the East African ostrich is a red-necked subspecies variety of the common ostrich and is endemic to East Africa. It is one of the largest birds in the world, second only to its sis ...
es of East Africa (''S. c. massaicus'') average in males and in females, while the nominate subspecies, the North African ostrich
The North African ostrich, red-necked ostrich, or Barbary ostrich (''Struthio camelus camelus'') is the nominate subspecies of the common ostrich from West and North Africa. It is the largest subspecies, making it the largest living bird.
Evolu ...
(''S. c. camelus''), was found to average in unsexed adults. Exceptional male ostriches (in the nominate subspecies) can weigh up to . At sexual maturity (two to four years), male common ostriches can be from in height, while female common ostriches range from tall. New chicks are fawn
Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
in color, with dark brown spots.[ During the first year of life, chicks grow at about per month. At one year of age, common ostriches weigh approximately . Their lifespan is typically 40–45 years.
The feathers of adult males are mostly black, with white ]primaries
Primary elections, or direct primary are a voting process by which voters can indicate their preference for their party's candidate, or a candidate in general, in an upcoming general election, local election, or by-election. Depending on the c ...
and a white tail. However, the tail of one subspecies is buff. Females and young males are grayish-brown and white. The head and neck of both male and female ostriches is nearly bare, with a thin layer of down.[ The skin of the female's neck and thighs is pinkish gray,][ while the male's is gray or pink dependent on subspecies.
File:Afrikanischer Strauss Portrait.jpg, Head feathers are a thin layer of down.
File:Ostrich, mouth open.jpg, Long eyelashes protect the eyes.
File:Ostrich foot.jpg, Feet are frequently missing the nail on the outer toe.
File:The Childrens Museum of Indianapolis - Ostrich skull.jpg, Skull
File:OstrichWing.jpg, Claws on the wings
File:Avestruz alta.jpg, alt=Ostrich skeleton
File:Common ostrich (Struthio camelus australis) male running composite.jpg, Male running, ]Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
, alt=Male, Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
The long neck and legs keep their head up to above the ground, and their eyes are said to be the largest of any land vertebrate in diameter[ helping them to see predators at a great distance. The eyes are shaded from sunlight from above.][ However, the head and ]bill
Bill(s) may refer to:
Common meanings
* Banknote, paper cash (especially in the United States)
* Bill (law), a proposed law put before a legislature
* Invoice, commercial document issued by a seller to a buyer
* Bill, a bird or animal's beak
Plac ...
are relatively small for the birds' huge size, with the bill measuring .
Their skin varies in color depending on the subspecies, with some having light or dark gray skin and others having pinkish or even reddish skin. The strong legs of the common ostrich are unfeathered and show bare skin, with the tarsus (the lowest upright part of the leg) being covered in scales: red in the male, black in the female. The tarsus of the common ostrich is the largest of any living bird, measuring in length. The bird is didactyl, having just two toes on each foot
The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...
(most birds have four), with the nail
Nail or Nails may refer to:
In biology
* Nail (anatomy), toughened protective protein-keratin (known as alpha-keratin, also found in hair) at the end of an animal digit, such as fingernail
* Nail (beak), a plate of hard horny tissue at the tip ...
on the larger, inner toe resembling a hoof
The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rumin ...
. The outer toe has no nail. The reduced number of toes is an adaptation that appears to aid in running, useful for getting away from predators. Common ostriches can run at a speed over and can cover in a single stride. The wings reach a span of about , and the wing chord measurement of is around the same size as for the largest flying birds.
The feathers lack the tiny hooks that lock together the smooth external feathers of flying birds, and so are soft and fluffy and serve as insulation. Common ostriches can tolerate a wide range of temperatures. In much of their habitat, temperatures vary as much as between night and day. Their temperature control relies in part on behavioral thermoregulation. For example, they use their wings to cover the naked skin of the upper legs and flanks to conserve heat, or leave these areas bare to release heat. The wings also function as stabilizers to give better maneuverability when running. Tests have shown that the wings are actively involved in rapid braking, turning, and zigzag maneuvers. They have 50–60 tail feathers, and their wings have 16 primary, four alular
The alula , or bastard wing, (plural ''alulae'') is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ''ala'', meaning "wing". The ...
, and 20–23 secondary feathers.
The common ostrich's sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
is flat, lacking the keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
to which wing muscles attach in flying birds. The beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...
is flat and broad, with a rounded tip. Like all ratites
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics o ...
, the ostrich has no crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
,[ and it also lacks a ]gallbladder
In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...
[ and the ]caecum
The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix, to which it is joined). The w ...
is . Unlike all other living birds, the common ostrich secretes urine separately from feces.[ All other birds store the urine and feces combined in the ]coprodeum
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior Body orifice, orifice that serves as the only opening for the Gut (anatomy), digestive, Reproductive system, reproductive, and urinary tracts (if present) of many vertebrat ...
, but the ostrich stores the feces in the terminal rectum.[ They also have unique ]pubic bones
In vertebrates, the pubic region ( la, pubis) is the most forward-facing (ventral and anterior) of the three main regions making up the coxal bone. The left and right pubic regions are each made up of three sections, a superior ramus, inferior r ...
that are fused to hold their gut. Unlike most birds, the males have a copulatory organ
A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, ...
, which is retractable and long. Their palate
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity.
A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...
differs from other ratites in that the sphenoid and palatal
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity.
A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...
bones are unconnected.
Taxonomy
The common ostrich was originally described by Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
from Sweden in his 18th-century work, ''Systema Naturae
' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
'' under its current binomial name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
.[ Its ]genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
is derived from the Late Latin
Late Latin ( la, Latinitas serior) is the scholarly name for the form of Literary Latin of late antiquity.Roberts (1996), p. 537. English dictionary definitions of Late Latin date this period from the , and continuing into the 7th century in t ...
''struthio'' meaning "ostrich". The specific name is an allusion to "strouthokamelos" the Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
name for the ostrich, meaning camel-sparrow, the "camel" term referring to its dry habitat.[ Στρουθοκάμηλος is still the modern Greek name for the ostrich.
The common ostrich belongs to the ]ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
order
Order, ORDER or Orders may refer to:
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
* Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
Struthioniformes
Struthioniformes is an order of birds with only a single extant family, Struthionidae, containing the ostriches. Several other extinct families are known, spanning across the Northern Hemisphere, from the Early Eocene to the early Pliocene, includ ...
. Other members include rheas
The rheas ( ), also known as ñandus ( ) or South American ostriches, are large ratites (flightless birds without a keel on their sternum bone) in the order Rheiformes, native to South America, distantly related to the ostrich and emu. Most taxo ...
, emu
The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus ''Dromaius''. The emu' ...
s, cassowaries
Cassowaries ( tpi, muruk, id, kasuari) are flightless birds of the genus ''Casuarius'' in the order Casuariiformes. They are classified as ratites (flightless birds without a keel (bird anatomy), keel on their sternum bones) and are native t ...
, moa
Moa are extinct giant flightless birds native to New Zealand.
The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as
Kale moa and Moa Samoa.
Moa or MOA may also refer ...
, kiwi
Kiwi most commonly refers to:
* Kiwi (bird), a flightless bird native to New Zealand
* Kiwi (nickname), a nickname for New Zealanders
* Kiwifruit, an edible berry
* Kiwi dollar or New Zealand dollar, a unit of currency
Kiwi or KIWI may also refe ...
and the largest known bird ever, the now-extinct elephant bird
Elephant birds are members of the extinct ratite family Aepyornithidae, made up of flightless birds that once lived on the island of Madagascar. They are thought to have become extinct around 1000-1200 CE, probably as a result of human activity. ...
(''Aepyornis''). However, the classification of the ratites as a single order has always been questioned, with the alternative classification restricting the Struthioniformes to the ostrich lineage and elevating the other groups.
Subspecies
Four subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
are recognized:
Some analyses indicate that the Somali ostrich is now considered a full species; the Tree of Life Project, ''The Clements Checklist of Birds of the World
''The Clements Checklist of Birds of the World'' is a book by Jim Clements which presents a list of the bird species of the world.
The most recent printed version is the sixth edition (2007), but has been updated yearly, the last version in 2022 ...
'', BirdLife International
BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...
, and the IOC World Bird List
''Birds of the World: Recommended English Names'' is a paperback book, written by Frank Gill and Minturn Wright on behalf of the International Ornithologists' Union. The book is an attempt to produce a standardized set of English names for all b ...
recognize it as a different species. A few authorities, including the ''Howard and Moore Complete Checklist of the Birds of the World
The ''Howard and Moore Complete Checklist of the Birds of the World'' is a book by Richard Howard and Alick Moore which presents a list of the bird species of the world. It was the first single-volume world bird list to include subspecies names, ...
'', do not recognize it as separate. Mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
haplotype
A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent.
Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...
comparisons suggest that it diverged from the other ostriches not quite 4 mya
Mya may refer to:
Brands and product names
* Mya (program), an intelligent personal assistant created by Motorola
* Mya (TV channel), an Italian Television channel
* Midwest Young Artists, a comprehensive youth music program
Codes
* Burmese ...
due to formation of the East African Rift
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of a ...
. Hybridization with the subspecies that evolved southwestwards of its range, ''S. c. massaicus'', has apparently been prevented from occurring on a significant scale by ecological separation; the Somali ostrich prefers bushland where it browses middle-height vegetation for food while the Masai ostrich is, like the other subspecies, a grazing
In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
bird of the open savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
and ''miombo
The Miombo woodland is a tropical and subtropical grasslands, savannas, and shrublands biome (in the World Wide Fund for Nature scheme) located primarily in Central Africa. It includes four woodland savanna ecoregions (listed below) characterized b ...
'' habitat.[
The population from ]Río de Oro
Río de Oro (Spanish for "Gold River"; , ''wādī-að-ðahab'', often transliterated as ''Oued Edhahab'') was, with Saguia el-Hamra, one of the two territories that formed the Spanish province of Spanish Sahara after 1969; it had been taken as ...
was once separated as ''Struthio camelus spatzi'' because its eggshell pores were shaped like a teardrop and not round. As there is considerable variation of this character and there were no other differences between these birds and adjacent populations of ''S. c. camelus'', the separation is no longer considered valid.[ However, a study analysing the postcranial skeleton of all living and recently extinct species and subspecies of ostriches appeared to validate ''S. c. spatzi'' based on its unique skeletal proportions. This population disappeared in the latter half of the 20th century. There were 19th-century reports of the existence of small ostriches in North Africa; these are referred to as Levaillant's ostrich (''Struthio bidactylus'') but remain a hypothetical form not supported by material evidence.][
]
Distribution and habitat
Common ostriches formerly occupied Africa north and south of the Sahara
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
, East Africa, Africa south of the rainforest belt, and much of Asia Minor
Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
. Today common ostriches prefer open land and are native to the savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
s and Sahel
The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid c ...
of Africa, both north and south of the equatorial forest zone. In southwest Africa they inhabit the semi-desert or true desert. Farmed common ostriches in Australia have established feral
A feral () animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some ...
populations. The Arabian ostrich
The Arabian ostrich (''Struthio camelus syriacus''), Syrian ostrich, or Middle Eastern ostrich is an extinct subspecies of the ostrich that lived on the Arabian Peninsula and in the Near East until the mid-20th century.
Distribution
Its range s ...
es in the Near and Middle East were hunted to extinction by the middle of the 20th century. Attempts to reintroduce the common ostrich into Israel have failed. Common ostriches have occasionally been seen inhabiting islands on the Dahlak Archipelago, in the Red Sea
The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...
near Eritrea
Eritrea ( ; ti, ኤርትራ, Ertra, ; ar, إرتريا, ʾIritriyā), officially the State of Eritrea, is a country in the Horn of Africa region of Eastern Africa, with its capital and largest city at Asmara. It is bordered by Ethiopia ...
.
Research conducted by the Birbal Sahni Institute of Palaeobotany
The Birbal Sahni Institute of Palaeosciences (formerly, Birbal Sahni Institute of Palaeobotany; BSIP) is an autonomous institute constituted under the Department of Science and Technology (India), Department of Science and Technology, Government ...
in India found molecular evidence that ostriches lived in India 25,000 years ago. DNA tests on fossilized eggshells recovered from eight archaeological sites in the states of Rajasthan, Gujarat and Madhya Pradesh found 92% genetic similarity between the eggshells and the North African ostrich, so these could have been fairly distant relatives.
Ostriches are farmed in Australia. Many escaped, however, and feral ostriches now roam the Australian outback
The Outback is a remote, vast, sparsely populated area of Australia. The Outback is more remote than the bush. While often envisaged as being arid, the Outback regions extend from the northern to southern Australian coastlines and encompass a n ...
.
Behaviour and ecology
Common ostriches normally spend the winter months in pairs or alone. Only 16 percent of common ostrich sightings were of more than two birds. During breeding season and sometimes during extreme rainless periods ostriches live in nomad
A nomad is a member of a community without fixed habitation who regularly moves to and from the same areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the popu ...
ic groups of five to 100 birds (led by a top hen) that often travel together with other grazing
In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
animals, such as zebras or antelope
The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia.
Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...
s. Ostriches are diurnal, but may be active on moonlit nights. They are most active early and late in the day. The male common ostrich territory is between .[
With their acute eyesight and hearing, common ostriches can sense predators such as lions from far away. When being pursued by a predator, they have been known to reach speeds in excess of ,] or possibly and can maintain a steady speed of , which makes the common ostrich the world's fastest two-legged animal. When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.[
When threatened, common ostriches run away, but they can cause serious injury and death with kicks from their powerful legs.] Their legs can only kick forward.[
]
Feeding
They mainly feed on seeds, shrubs, grass, fruit, and flowers;[ occasionally they also eat insects such as ]locust
Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstanc ...
s, small reptiles such as lizards, and occasionally animal remains left by carnivorous predators. Lacking teeth, they swallow pebbles that act as gastrolith
A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In othe ...
s to grind food in the gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, dinosaurs, birds), earthworms, some gastropods, so ...
. When eating, they will fill their gullet
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
with food, which is in turn passed down their esophagus in the form of a ball called a bolus
Bolus may refer to:
Geography
* Bolus, Iran, a village in Ardabil Province, Iran
* Bolus, or Baulus, an Anatolian village on the site of ancient Berissa
Medicine
* Bolus (digestion), a ball-shaped mass moving through the digestive tract
* Bolus ...
. The bolus may be as much as . After passing through the neck (there is no crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
) the food enters the gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, dinosaurs, birds), earthworms, some gastropods, so ...
and is worked on by the aforementioned pebbles. The gizzard can hold as much as , of which up to 45% may be sand and pebbles.[ Common ostriches can go without drinking for several days, using ]metabolic water
Metabolic water refers to water created inside a living organism through their metabolism, by oxidizing energy-containing substances in their food. Animal metabolism produces about 107-110 grams of water per 100 grams of fat, 41-42 grams of water ...
and moisture in ingested plants,[ but they enjoy liquid water and frequently take baths where it is available.] They can survive losing up to 25% of their body weight through dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
.[
]
Mating
Common ostriches become sexually mature
Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...
when they are 2 to 4 years old; females mature about six months earlier than males. As with other birds, an individual may reproduce several times over its lifetime. The mating season
Seasonal breeders are animal species that successfully mate only during certain times of the year. These times of year allow for the optimization of survival of young due to factors such as ambient temperature, food and water availability, and cha ...
begins in March or April and ends sometime before September. The mating process differs in different geographical regions. Territorial
A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal.
In international politics, a territory is usually either the total area from which a state may extract power resources or a ...
males typically boom
Boom may refer to:
Objects
* Boom (containment), a temporary floating barrier used to contain an oil spill
* Boom (navigational barrier), an obstacle used to control or block marine navigation
* Boom (sailing), a sailboat part
* Boom (windsurfi ...
(by inflating their neck) in defense of their territory and harem of two to seven hens; the successful male may then mate with several females in the area, but will only form a pair bond with a 'major' female.
The cock performs with his wings, alternating wing beats, until he attracts a mate. They will go to the mating area and he will maintain privacy by driving away all intruders. They graze until their behavior is synchronized, then the feeding becomes secondary and the process takes on a ritualistic appearance. The cock will then excitedly flap alternate wings again and start poking on the ground with his bill. He will then violently flap his wings to symbolically clear out a nest in the soil. Then, while the hen runs a circle around him with lowered wings, he will wind his head in a spiral motion. She will drop to the ground and he will mount for copulation. Common ostriches raised entirely by humans may direct their courtship behavior not at other ostriches, but toward their human keepers.[
File:Ostriches Kgalagadi Transfrontier Park.jpeg, Only 15% of the surviving chicks reach 1 year of age.
File:Struthio camelus - Strausskueken.jpg, alt=Ostrich chick
File:2014-12-02 12h28 Ostrich Farm anagoria.JPG, Recently hatched from egg, alt=Chick, recently hatched from egg
File:Ostrich hen with chicks, northern Serengeti.jpg, Hen with chicks
File:Struthio camelus -Serengeti, Tanzania -female on nest-8.jpg, Female incubating eggs, alt=Female incubating eggs in a shallow nest on the ground
File:Struthio camelus - strus (2).JPG, Nest
]
The female common ostrich lays her fertilized eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
in a single communal nest, a simple pit, deep and wide,[ scraped in the ground by the male. The dominant female lays her eggs first; when it is time to cover them for incubation, she discards extra eggs from the weaker females, leaving about 20 in most cases.] A female common ostrich can distinguish her own eggs from the others in a communal nest.[ Ostrich eggs are the largest of all eggs,][ though they are actually the smallest eggs relative to the size of the adult bird – on average they are long, wide, and weigh , over 20 times the weight of a chicken's egg and only 1 to 4% the size of the female.][ They are glossy cream-colored, with thick shells marked by small pits.]
The eggs are incubated by the females by day and by the males by night. This uses the coloration of the two sexes to escape detection of the nest, as the drab female blends in with the sand, while the black male is nearly undetectable in the night. The incubation period is 35 to 45 days, which is rather short compared to other ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
s. This is believed to be the case due to the high rate of predation.[ Typically, the male defends the hatchlings and teaches them to feed, although males and females cooperate in rearing chicks. Fewer than 10% of nests survive the 9-week period of laying and incubation, and of the surviving chicks, only 15% of those survive to 1 year of age.][ However, among those common ostriches who survive to adulthood, the species is one of the longest-living bird species. Common ostriches in captivity have lived to 62 years and 7 months.]
Predators
As a flightless species in the rich biozone of the African savanna, the common ostrich faces a variety of formidable predators throughout its life cycle. Animals that prey on ostriches of all ages may include cheetahs, lions, leopard
The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...
s, African hunting dog
The African wild dog (''Lycaon pictus''), also called the painted dog or Cape hunting dog, is a wild canine which is a native species to sub-Saharan Africa. It is the largest wild canine in Africa, and the only extant member of the genus '' Lyc ...
s, spotted hyena
The spotted hyena (''Crocuta crocuta''), also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus ''Crocuta'', native to sub-Saharan Africa. It is listed as being of least concern by the IUC ...
s, and Nile crocodile
The Nile crocodile (''Crocodylus niloticus'') is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed throughout sub-Saharan Africa, occurring mostly in the central, eastern ...
s. Predators of nests and young common ostriches include jackal
Jackals are medium-sized canids native to Africa and Eurasia. While the word "jackal" has historically been used for many canines of the subtribe canina, in modern use it most commonly refers to three species: the closely related black-backed ...
s, various birds of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators ...
, warthog
''Phacochoerus'' is a genus in the family Suidae, commonly known as warthogs (pronounced ''wart-hog''). They are pigs who live in open and semi-open habitats, even in quite arid regions, in sub-Saharan Africa. The two species were formerly cons ...
s, mongoose
A mongoose is a small terrestrial carnivorous mammal belonging to the family Herpestidae. This family is currently split into two subfamilies, the Herpestinae and the Mungotinae. The Herpestinae comprises 23 living species that are native to so ...
, and Egyptian vulture
The Egyptian vulture (''Neophron percnopterus''), also called the white scavenger vulture or pharaoh's chicken, is a small Old World vulture and the only member of the genus ''Neophron''. It is widely distributed from the Iberian Peninsula and ...
s.[ Egyptian vultures have been known to hurl stones at ostrich eggs to crack them open so they can eat their contents.
Due to predation pressure, common ostriches have many antipredator tactics. Though they can deliver formidable kicks, they use their great eyesight and speed to run from most of their predators.][ Since ostriches that have detected predators are almost impossible to catch, most predators will try to ambush an unsuspecting bird using obstructing vegetation or other objects.] Some ostriches forage with other ostriches or mammals such as wildebeest
Wildebeest ( , , ), also called gnu ( or ), are antelopes of the genus ''Connochaetes'' and native to Eastern and Southern Africa. They belong to the family Bovidae, which includes true antelopes, cattle, goats, sheep, and other even-toe ...
s and zebras to detect predators more efficiently. If the nest or young are threatened, either or both of the parents may create a distraction, feigning injury.[ However, they may sometimes fiercely fight predators, especially when chicks are being defended, and are capable of killing humans, hyenas, and even lions in such confrontations.][
Usually, ostrich hunting is done by male cheetah coalitions in the Kalahari region during the night, when ostrich's vigilance is less effective. Cheetahs in other regions rarely hunt ostriches, but an exceptional coalition composed of three ]East African cheetah
The East African cheetah (''Acinonyx jubatus jubatus''), is a cheetah population in East Africa. It lives in grasslands and savannas of Tanzania, Kenya, Uganda and Somalia. The cheetah inhabits mainly the Serengeti ecosystem, including Maasai M ...
s has been reported in Kenya.[Sunquist, Mel, and Fiona Sunquist. Wild cats of the world. University of Chicago Press, 2017.] Similarly, lions hunt ostriches mainly in the Kalahari region and not in other regions, or take ostriches as only a small percentage of their prey.[ Overall, due to their speed, vigilance, and possibly dangerous kick, ostriches are usually avoided by most predators, including lions, leopards, wild dogs, and cheetahs.] Despite parental care, 90% is typical for chick mortality, most of it caused by predation.
Physiology
Respiration
Anatomy
Morphology of the common ostrich lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
indicates that the structure conforms to that of the other avian species, but still retains parts of its primitive avian species, ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
, structure. The opening to the respiratory pathway begins with the laryngeal cavity lying posterior to the choanae
The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...
within the buccal cavity
The buccal space (also termed the buccinator space) is a fascial spaces of the head and neck, fascial space of the head and neck (sometimes also termed fascial tissue spaces or tissue spaces). It is a potential space in the cheek, and is paired on ...
. The tip of the tongue then lies anterior
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
to the choanae, excluding the nasal respiratory pathway from the buccal cavity. The trachea lies ventrally
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
to the cervical vertebrae extending from the larynx
The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about ...
to the syrinx
In classical Greek mythology, Syrinx (Greek Σύριγξ) was a nymph and a follower of Artemis, known for her chastity. Pursued by the amorous god Pan, she ran to a river's edge and asked for assistance from the river nymphs. In answer, sh ...
, where the trachea enters the thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
, dividing into two primary bronchi
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
, one to each lung, in which they continue directly through to become mesobronchi. Ten different air sacs attach to the lungs to form areas for respiration. The most posterior air sacs
Air sacs are spaces within an organism where there is the constant presence of air. Among modern animals, birds possess the most air sacs (9–11), with their extinct dinosaurian relatives showing a great increase in the pneumatization (presence ...
(abdominal and post-thoracic) differ in that the right abdominal air sac is relatively small, lying to the right of the mesentery
The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines ...
, and dorsally
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
to the liver. While the left abdominal air sac is large and lies to the left of the mesentery. The connection from the main mesobronchi to the more anterior
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
air sacs including the interclavicular, lateral clavicular, and pre-thoracic sacs known as the ventrobronchi region. While the caudal
Caudal may refer to:
Anatomy
* Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism
* Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into the ...
end of the mesobronchus branches into several dorsobronchi. Together, the ventrobronchi and dorsobronchi are connected by intra-pulmonary airways, the parabronchi
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capabl ...
, which form an arcade structure within the lung called the paleopulmo. It is the only structure found in primitive birds such as ratites.
The largest air sacs found within the respiratory system are those of the post-thoracic region, while the others decrease in size respectively, the interclavicular (unpaired), abdominal, pre-thoracic, and lateral clavicular sacs. The adult common ostrich lung lacks connective tissue known as interparabronchial septa, which render strength to the non-compliant avian lung in other bird species. Due to this the lack of connective tissue surrounding the parabronchi and adjacent parabronchial lumen, they exchange blood capillaries or avascular
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
epithelial plates. Like mammals, ostrich lungs contain an abundance of type II cells at gas exchange sites; an adaptation for preventing lung collapse during slight volume changes.
Function
The common ostrich is an endotherm
An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inste ...
and maintains a body temperature of in its extreme living temperature conditions, such as the heat of the savanna and desert regions of Africa.[ The ostrich utilizes its respiratory system via a costal pump for ventilation rather than a diaphragmatic pump as seen in most mammals.][ Thus, they are able to use a series of air sacs connected to the ]lungs
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of th ...
. The use of air sacs forms the basis for the three main avian respiratory characteristics:
# Air is able to flow continuously in one direction through the lung, making it more efficient than the mammalian lung.
# It provides birds with a large residual volume, allowing them to breathe much more slowly and deeply than a mammal of the same body mass.
# It provides a large source of air that is used not only for gaseous exchange, but also for the transfer of heat by evaporation.[
]
Inhalation begins at the mouth and the nostrils located at the front of the beak. The air then flows through the anatomical dead space of a highly vascular trachea ( ) and expansive bronchial system, where it is further conducted to the posterior air sacs.[ Air flow through the ]parabronchi
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capabl ...
of the paleopulmo is in the same direction to the dorsobronchi during inspiration and expiration. Inspired air moves into the respiratory system as a result of the expansion of thoraco abdominal cavity; controlled by inspiratory muscles. During expiration, oxygen poor air flows to the anterior air sacs[ and is expelled by the action of the expiratory muscles. The common ostrich air sacs play a key role in respiration, since they are capacious, and increase surface area (as described by the ]Fick Principle
The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known:
* Amount of marker substance taken up by the organ per unit time
* Concentration of marker substance in arteria ...
).[ The oxygen rich air flows unidirectionally across the respiratory surface of the lungs; providing the blood that has a crosscurrent flow with a high concentration of oxygen.][
To compensate for the large "dead" space, the common ostrich trachea lacks valves to allow faster inspiratory air flow.][ In addition, the ]total lung capacity
Lung volumes and lung capacities refer to the volume of air in the lungs at different phases of the respiratory cycle.
The average total lung capacity of an adult human male is about 6 litres of air.
Tidal breathing is normal, resting breathin ...
of the respiratory system, (including the lungs and ten air sacs) of a ostrich is about , with a tidal volume
Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per inspiration or 7 ml/kg of body mass.
Mechanical vent ...
ranging from . The tidal volume is seen to double resulting in a 16-fold increase in ventilation.[ Overall, ostrich respiration can be thought of as a high velocity-low pressure system.][ At rest, there is a small pressure difference between the ostrich air sacs and the atmosphere, suggesting simultaneous filling and emptying of the air sacs.][
The increase in respiration rate from the low range to the high range is sudden and occurs in response to ]hyperthermia
Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...
. Birds lack sweat glands, so when placed under stress due to heat, they heavily rely upon increased evaporation from the respiratory system for heat transfer. This rise in respiration rate
The respiration rate is a parameter which is used in Ecological modeling, ecological and agronomical modeling.
In theoretical production ecology and aquaculture, it typically refers to cellular respiration, respiration per unit of time (usually l ...
however is not necessarily associated with a greater rate of oxygen consumption.[ Therefore, unlike most other birds, the common ostrich is able to dissipate heat through panting without experiencing ]respiratory alkalosis
Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide. This condition is one of the four primary di ...
by modifying ventilation of the respiratory medium. During hyperpnea
Hyperpnea, or hyperpnoea (forced respiration) is increased volume of air taken during breathing. It can occur with or without an increase in respiration rate. It is characterized by deep breathing. It may be physiologic—as when required by oxygen ...
ostriches pant at a respiratory rate of 40–60 cycles per minute, versus their resting rate of 6–12 cycles per minute.[ Hot, dry, and moisture lacking properties of the common ostrich respiratory medium affect oxygen's diffusion rate (]Henry's Law
In physical chemistry, Henry's law is a gas law that states that the amount of dissolved gas in a liquid is directly proportional to its partial pressure above the liquid. The proportionality factor is called Henry's law constant. It was formulat ...
).
Common ostriches develop via Intussusceptive angiogenesis
Intussusceptive angiogenesis also known as splitting angiogenesis, is a type of angiogenesis, the process whereby a new blood vessel is created. By intussusception a new blood vessel is created by splitting of an existing blood vessel in two. In ...
, a mechanism of blood vessel
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
formation, characterizing many organs.[ It is not only involved in vasculature expansion, but also in angioadaptation of vessels to meet physiological requirements.] The use of such mechanisms demonstrates an increase in the later stages of lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
development, along with elaborate parabronchial vasculature
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, and reorientation of the gas exchange
Gas exchange is the physical process by which gases move passively by Diffusion#Diffusion vs. bulk flow, diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liqui ...
blood capillaries to establish the crosscurrent system at the blood-gas barrier.[ The blood–gas barrier (BGB) of their lung tissue is thick. The advantage of this thick barrier may be protection from damage by large volumes of blood flow in times of activity, such as running,][ since air is pumped by the air sacs rather than the lung itself. As a result, the ]capillaries
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
in the parabronchi have thinner walls, permitting more efficient gaseous exchange.[ In combination with separate pulmonary and systemic circulatory systems, it helps to reduce stress on the BGB.][
]
Circulation
Heart anatomy
The common ostrich heart is a closed system, contractile chamber. It is composed of myogenic The myogenic mechanism is how arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow constant within the blood vessel. Myogenic response refers to a contraction initiated by the myocyte itself instead of ...
muscular tissue associated with heart contraction features. There is a double circulatory plan in place possessing both a pulmonary circuit
The pulmonary circulation is a division of the circulatory system in all vertebrates. The circuit begins with deoxygenated blood returned from the body to the right atrium of the heart where it is pumped out from the right ventricle to the lungs. ...
and systemic circuit.
The common ostrich's heart has similar features to other avian species, like having a conically shaped heart and being enclosed by a pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
layer. Moreover, similarities also include a larger right atrium
The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves.
There are two atr ...
volume and a thicker left ventricle
A ventricle is one of two large chambers toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in the upper ...
to fulfil the systemic circuit. The ostrich heart has three features that are absent in related birds:
# The right atrioventricular valve
A heart valve is a one-way valve that allows blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow through the heart. A heart v ...
is fixed to the interventricular septum
The interventricular septum (IVS, or ventricular septum, or during development septum inferius) is the stout wall separating the ventricles, the lower chambers of the heart, from one another.
The ventricular septum is directed obliquely backwar ...
, by a thick muscular stock, which prevents back-flow of blood into the atrium when ventricular systole
The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following ...
is occurring. In the fowl
Fowl are birds belonging to one of two biological orders, namely the gamefowl or landfowl (Galliformes) and the waterfowl (Anseriformes). Anatomical and molecular similarities suggest these two groups are close evolutionary relatives; together ...
this valve is only connected by a short septal attachment.
# Pulmonary vein
The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four ''main pulmonary veins'', two from each lung that drain into the left atrium of the heart. The pulmonary vein ...
s attach to the left atrium separately, and also the opening to the pulmonary veins are separated by a septum.
# Moderator bands, full of Purkinje fibers
The Purkinje fibers (; often incorrectly ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purkinje fibers are specia ...
, are found in different locations in the left and right ventricles. These bands are associated with contractions of the heart and suggests this difference causes the left ventricle to contract harder to create more pressure for a completed circulation of blood around the body.
The atrioventricular node
The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of t ...
position differs from other fowl. It is located in the endocardium
The endocardium is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the va ...
of the atrial surface of the right atrioventricular valve. It is not covered by connective tissue, which is characteristic of vertebrate heart anatomy. It also contains fewer myofibrils
A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as muscle fibers, and these cells contain many chains of myofibrils. Each myofibr ...
than usual myocardial cells. The AV node connects the atrial and ventricular chambers. It functions to carry the electrical impulse from the atria to the ventricle. Upon view, the myocardial cells are observed to have large densely packed chromosomes within the nucleus.[
The ]coronary Coronary () may, as shorthand in English, be used to mean:
* Coronary circulation, the system of arteries and veins in mammals
** Coronary artery disease
** Coronary occlusion
** A myocardial infarction, a heart attack
As adjective
* Referring t ...
arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...
start in the right and left aortic sinus and provide blood to the heart muscle in a similar fashion to most other vertebrates.[ Other domestic birds capable of flight have three or more ]coronary Coronary () may, as shorthand in English, be used to mean:
* Coronary circulation, the system of arteries and veins in mammals
** Coronary artery disease
** Coronary occlusion
** A myocardial infarction, a heart attack
As adjective
* Referring t ...
arteries that supply blood to the heart muscle. The blood supply by the coronary arteries are fashioned starting as a large branch over the surface of the heart. It then moves along the coronary groove
The coronary sulcus (also called coronary groove, auriculoventricular groove, atrioventricular groove, AV groove) is a groove on the surface of the heart at the base of right auricle that separates the atria from the ventricles. The structure co ...
and continues on into the tissue as interventricular branches toward the apex of the heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to ...
. The atria, ventricles, and septum
In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate.
Examples
Human anatomy
* Interatri ...
are supplied of blood by this modality. The deep branches of the coronary arteries found within the heart tissue are small and supply the interventricular and right atrioventricular valve with blood nutrients for which to carry out their processes. The interatrial artery of the ostrich is small in size and exclusively supplies blood to only part of the left auricle and interatrial septum
In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate.
Examples
Human anatomy
* Interatri ...
.[
These ]Purkinje fibers
The Purkinje fibers (; often incorrectly ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purkinje fibers are specia ...
(p-fibers) found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the heart to contract. The Purkinje cells are mostly found within both the endocardium and the sub-endocardium. The sinoatrial node
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approximat ...
shows a small concentration of Purkinje fibers, however, continuing through the conducting pathway of the heart the bundle of his
The bundle of His (BH) or His bundle (HB) ( "hiss"Medical Terminology for Health Professions, Spiral bound Version'. Cengage Learning; 2016. . pp. 129–.) is a collection of heart muscle cells specialized for electrical conduction. As part of t ...
shows the highest amount of these Purkinje fibers.
Blood composition
The red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
count per unit volume in the ostrich is about 40% of that of a human; however, the red blood cells of the ostrich are about three times larger than the red blood cells of a human. The blood oxygen affinity, known as P50, is higher than that of both humans and similar avian species. The reason for this decreased oxygen affinity is due to the hemoglobin configuration found in common ostrich blood. The common ostrich's tetramer
A tetramer () (''tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula Ti ...
is composed of hemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...
type A and D, compared to typical mammalian tetramers composed of hemoglobin type A and B; hemoglobin D configuration causes a decreased oxygen affinity at the site of the respiratory surface.
During the embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
nic stage, Hemoglobin E
Hemoglobin E (HbE) is an abnormal hemoglobin with a single point mutation in the β chain. At position 26 there is a change in the amino acid, from glutamic acid to lysine (E26K). Hemoglobin E is very common among people of Southeast Asian, Northea ...
is present. This subtype increases oxygen affinity in order to transport oxygen across the allantoic membrane of the embryo. This can be attributed to the high metabolic need of the developing embryo, thus high oxygen affinity serves to satisfy this demand. When the chick hatches hemoglobin E diminishes while hemoglobin A and D increase in concentration. This shift in hemoglobin concentration results in both decreased oxygen affinity and increased P50 value.
Furthermore, the P50 value is influenced by differing organic modulators. In the typical mammalian RBC 2,3 – DPG causes a lower affinity for oxygen. 2,3- DPG constitutes approximately 42–47%, of the cells phosphate of the embryonic ostrich. However, the adult ostrich have no traceable 2,3- DPG.In place of 2,3-DPG the ostrich uses inositol polyphosphate
Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate e ...
s (IPP), which vary from 1–6 phosphates per molecule. In relation to the IPP, the ostrich also uses ATP
ATP may refer to:
Companies and organizations
* Association of Tennis Professionals, men's professional tennis governing body
* American Technical Publishers, employee-owned publishing company
* ', a Danish pension
* Armenia Tree Project, non ...
to lower oxygen affinity. ATP has a consistent concentration of phosphate in the cell around 31% at incubation period
Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, the i ...
s and dropping to 16–20% in 36-day-old chicks. However, IPP has low concentrations, around 4%, of total phosphate concentration in embryonic stages, but the IPP concentration jumps to 60% of total phosphate of the cell. The majority of phosphate concentration switches from 2,3- DPG to IPP, suggesting the result of the overall low oxygen affinity is due to these varying polyphosphates.
Concerning immunological adaptation, it was discovered that wild common ostriches have a pronounced non-specific immunity defense, with blood content reflecting high values of lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...
and phagocyte
Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek ', "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek ...
cells in medium. This is in contrast to domesticated ostriches, who in captivity develop high concentration of immunoglobulin
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
antibodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
in their circulation, indicating an acquired immunological response. It is suggested that this immunological adaptability may allow this species to have a high success rate of survival in variable environmental settings.[
]
Osmoregulation
Physiological challenges
The common ostrich is a xeric
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this h ...
animal, due to the fact that it lives in habitats that are both dry and hot. Water is scarce in dry and hot environments, and this poses a challenge to the ostrich's water consumption. Also the ostrich is a ground bird and cannot fly to find water sources, which poses a further challenge. Because of their size, common ostriches cannot easily escape the heat of their environment; however, they dehydrate less than their small bird counterparts because of their small surface area to volume ratio
The surface-area-to-volume ratio, also called the surface-to-volume ratio and variously denoted sa/vol or SA:V, is the amount of surface area per unit volume of an object or collection of objects.
SA:V is an important concept in science and engin ...
. Hot, arid habitats pose osmotic stress, such as dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
, which triggers the common ostrich's homeostatic
In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and i ...
response to osmoregulate.
System overview
The common ostrich is well-adapted to hot, arid environments through specialization of excretory
Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after l ...
organs. The common ostrich has an extremely long and developed colon a length of approximately between th
coprodeum
and the paired caeca, which are around long. A well-developed caeca is also found and, in combination with the rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
, forms the microbial fermentation
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
chambers used for carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
breakdown. The catabolism
Catabolism () is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. Catabolism breaks down large molecules (such as polysaccharides, lipids, ...
of carbohydrates produces around of water that can be used internally. The majority of their urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
is stored in the coprodeum, and the feces
Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
are separately stored in the terminal colon. The coprodeum is located ventral to the terminal rectum and urodeum
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, ...
(where the ureters
The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epith ...
open). Found between the terminal rectum and coprodeum is a strong sphincter. The coprodeum and cloaca are the main osmoregulatory mechanisms used for the regulation and reabsorption of ions and water, or net water conservation. As expected in a species inhabiting arid regions, dehydration causes a reduction in fecal water, or dry feces. This reduction is believed to be caused by high levels of plasma aldosterone
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...
, which leads to rectal absorption of sodium and water. Also expected is the production of hyperosmotic
In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-imp ...
urine; cloacal urine has been found to be 800 mosmol/L. The U:P (urine:plasma) ratio of the common ostrich is therefore greater than one. Diffusion of water to the coprodeum (where urine is stored) from plasma across the epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
is voided. This void is believed to be caused by the thick mucosal
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
layering of the coprodeum.
Common ostriches have two kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
s, which are chocolate brown in color, are granular in texture, and lie in a depression in the pelvic cavity
The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor.
The pelvic cavity primarily contains the reproducti ...
of the dorsal wall. They are covered by peritoneum
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...
and a layer of fat. Each kidney is about long, wide, and divided into a cranial
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
, middle, and caudal
Caudal may refer to:
Anatomy
* Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism
* Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into the ...
sections by large veins. The caudal section is the largest, extending into the middle of the pelvis. The ureters
The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epith ...
leave the ventral caudomedial surface and continue caudally, near the midline into the opening of the urodeum of the cloaca. Although there is no bladder, a dilated pouch of ureter stores the urine until it is secreted continuously down from the ureter
The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...
s to the urodeum until discharged.
=Kidney function
=
Common ostrich kidneys are fairly large and so are able to hold significant amounts of solutes
In chemistry, a solution is a special type of homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. If the attractive forces between the solvent ...
. Hence, common ostriches drink relatively large volumes of water daily and excrete
Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...
generous quantities of highly concentrated urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
. It is when drinking water is unavailable or withdrawn that the urine becomes highly concentrated with uric acid and urates. It seems that common ostriches who normally drink relatively large amounts of water tend to rely on renal conservation of water within the kidney system when drinking water is scarce. Though there have been no official detailed renal studies conducted on the flow rate
Flow rate may refer to:
* Flow measurement, a quantification of bulk fluid movement
* Mass flow rate, the mass of a substance which passes per unit of time
* Volumetric flow rate, the volume of fluid which passes per unit time
** Discharge (hydrol ...
( Poiseuille's Law) and composition of the ureteral urine in the ostrich, knowledge of renal function
Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging.
Functions of a healthy kidney include maintaining a person's fluid ...
has been based on samples of cloacal urine, and samples or quantitative collections of voided urine. Studies have shown that the amount of water intake and dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
impacts the plasma osmolality
Plasma osmolality measures the body's electrolyte–water balance. There are several methods for arriving at this quantity through measurement or calculation.
Osmolality and osmolarity are measures that are technically different, but functional ...
and urine osmolality
Urine osmolality is a measure of urine concentration, in which large values indicate concentrated urine and small values indicate diluted urine. Consumption of water (including water contained in food) affects the osmolality of urine.
Osmolality ...
within various sized ostriches. During a normal hydration state of the kidneys, young ostriches tend to have a measured plasma osmolality of 284 mOsm
Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L ...
and urine osmolality of 62 mOsm. Adults have higher rates with a plasma osmolality of 330 mOsm and urine osmolality of 163 mOsm. The osmolality
Molality is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent. This contrasts with the definition of molarity which is based on a specified volume of solution.
A commonly used unit for molali ...
of both plasma and urine can alter in regards to whether there is an excess or depleted amount of water present within the kidneys. An interesting fact of common ostriches is that when water is freely available, the urine osmolality can reduce to 60–70 mOsm
Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L ...
, not losing any necessary solutes from the kidneys when excess water is excreted. Dehydrated or salt-loaded ostriches can reach a maximal urine osmolality of approximately 800 mOsm. When the plasma osmolality has been measured simultaneously with the maximal osmotic urine, it is seen that the urine:plasma ratio is 2.6:1, the highest encountered among avian species. Along with dehydration, there is also a reduction in flow rate
Flow rate may refer to:
* Flow measurement, a quantification of bulk fluid movement
* Mass flow rate, the mass of a substance which passes per unit of time
* Volumetric flow rate, the volume of fluid which passes per unit time
** Discharge (hydrol ...
from 20 L·d−1 to only 0.3–0.5 L·d−1.
In mammals and common ostriches, the increase of the glomerular filtration rate (GFR) and urine flow rate (UFR) is due to a high protein diets. As seen in various studies, scientists have measured clearance of creatinine
Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass).
Biological relevance
Serum creatinine (a blood measurement) is an import ...
, a fairly reliable marker of glomerular filtration rate (GFR). It has been seen that during normal hydration within the kidneys, the glomerular filtration rate is approximately 92 ml/min. However, when an ostrich experiences dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
for at least 48 hours (2 days), this value diminishes to only 25% of the hydrated GFR rate. Thus in response to the dehydration, ostrich kidneys secrete 440px
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...
small amounts of very viscous glomerular filtrates that have not been broken down and return them to the circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
through blood vessel
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
s. The reduction of GFR during dehydration is extremely high and so the fractional excretion of water (urine flow rate as a percentage of GFR) drops down from 15% at normal hydration to 1% during dehydration.
=Water intake and turnover
=
Common ostriches employ adaptive features to manage the dry heat and solar radiation
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
Solar irradiance is measured in watts per square metre (W/m ...
in their habitat. Ostriches will drink available water; however, they are limited in accessing water by being flightless. They are also able to harvest water through dietary means, consuming plants such as the '' Euphorbia heterochroma'' that hold up to 87% water.
Water mass accounts for 68% of body mass in adult common ostriches; this is down from 84% water mass in 35-day-old chicks. The differing degrees of water retention are thought to be a result of varying body fat mass. In comparison to smaller birds ostriches have a lower evaporative water loss resulting from their small body surface area per unit weight.
When heat stress is at its maximum, common ostriches are able to recover evaporative loss by using a metabolic water
Metabolic water refers to water created inside a living organism through their metabolism, by oxidizing energy-containing substances in their food. Animal metabolism produces about 107-110 grams of water per 100 grams of fat, 41-42 grams of water ...
mechanism to counter the loss by urine, feces, and respiratory evaporation. An experiment to determine the primary source of water intake in the ostrich indicated that while the ostrich does employ a metabolic water
Metabolic water refers to water created inside a living organism through their metabolism, by oxidizing energy-containing substances in their food. Animal metabolism produces about 107-110 grams of water per 100 grams of fat, 41-42 grams of water ...
production mechanism as a source of hydration, the most important source of water is food. When ostriches were restricted to the no food or water condition, the metabolic water production was only 0.5 L·d−1, while total water lost to urine, feces, and evaporation was 2.3 L·d−1. When the birds were given both water and food, total water gain was 8.5 L·d−1. In the food only condition total water gain was 10.1 L·d−1. These results show that the metabolic water
Metabolic water refers to water created inside a living organism through their metabolism, by oxidizing energy-containing substances in their food. Animal metabolism produces about 107-110 grams of water per 100 grams of fat, 41-42 grams of water ...
mechanism is not able to sustain water loss independently and that food intake, specifically of plants with a high water content such as ''Euphorbia heterochroma'', is necessary to overcome water loss challenges in the common ostrich's arid habitat.
In times of water deprivation, urine electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
and osmotic concentration
Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L ...
increases while urination rate decreases. Under these conditions urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
solute
In chemistry, a solution is a special type of homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. If the attractive forces between the solvent ...
:plasma ratio is approximately 2.5, or hyperosmotic
In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-imp ...
; that is to say that the ratio of solutes to water in the plasma is shifted down whereby reducing osmotic pressure in the plasma. Water is then able to be held back from excretion
Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...
, keeping the ostrich hydrated, while the passed urine contains higher concentrations of solute. This mechanism exemplifies how renal function facilitates water retention during periods of dehydration stress.
=Nasal glands
=
A number of avian species use nasal salt glands, alongside their kidneys, to control hypertonicity
In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane- ...
in their blood plasma
Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intra ...
. However, the common ostrich shows no nasal glandular function in regard to this homeostatic process. Even in a state of dehydration, which increases the osmolality
Molality is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent. This contrasts with the definition of molarity which is based on a specified volume of solution.
A commonly used unit for molali ...
of the blood, nasal salt glands show no sizeable contribution of salt elimination. Also, the overall mass of the glands was less than that of the duck's nasal gland. The common ostrich, having a heavier body weight, should have larger, heavier nasal glands to more effectively excrete salt from a larger volume of blood, but this is not the case. These unequal proportions contribute to the assumption that the common ostrich's nasal glands do not play any role in salt excretion. The nasal glands may be the result of an ancestral trait, which is no longer needed by the common ostrich, but has not been bred out of their gene pool.
=Biochemistry
=
The majority of the common ostrich's internal solutes are made up of sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
ions (), potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
ions (), chloride
The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...
ions (), total short-chain fatty acid Short-chain fatty acids (SCFAs) are fatty acids with fewer than six carbon atoms. Derived from intestinal microbial fermentation of indigestible foods, SCFAs are the main energy source of colonocytes, making them crucial to gastrointestinal health. ...
s (SCFA), and acetate
An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...
. The caecum contains a high water concentration with reduced levels nearing the terminal colon and exhibits a rapid fall in concentrations and small changes in and .
The colon is divided into three sections and takes part in solute absorption. The upper colon largely absorbs and SCFA and partially absorbs KCl. The middle colon absorbs and SCFA, with little net transfer of K+ and Cl−. The lower colon then slightly absorbs and water and secretes . There is no net movements of and SCFA found in the lower colon.
When the common ostrich is in a dehydrated state, plasma osmolality, , , and ions all increase; however, ions return to controlled concentration. The common ostrich also experiences an increase in haematocrit
The hematocrit () (Ht or HCT), also known by several other names, is the volume percentage (vol%) of red blood cells (RBCs) in blood, measured as part of a blood test. The measurement depends on the number and size of red blood cells. It is nor ...
, resulting in a hypovolemic state. Two antidiuretic hormones, Arginine vasotocin (AVT) and angiotensin
Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adrena ...
(AII), are increased in blood plasma as a response to hyperosmolality
Renal physiology (Latin ''rēnēs'', "kidneys") is the study of the physiology of the kidney. This encompasses all functions of the kidney, including maintenance of acid-base balance; regulation of fluid balance; regulation of sodium, potassium, ...
and hypovolemia
Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low extracellular fluid in the body. This may be due to either a loss of both salt and water or a decrease in blood volume. Hypovolemia refers to the los ...
. AVT triggers antidiuretic hormone
Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...
(ADH) which targets the nephrons
The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ca ...
of the kidney. ADH causes a reabsorption of water from the lumen of the nephron
The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ca ...
to the extracellular fluid
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
osmotically. These extracellular fluids then drain into blood vessels, causing a rehydrating effect. This drainage prevents loss of water by both lowering volume and increasing concentration of the urine. Angiotensin, on the other hand, causes vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
on the systemic arterioles and acts as a dipsogen A dipsogen is an agent that causes thirst. (From Greek language, Greek: ''δίψα'' ''(dipsa)'', "thirst" and the suffix ''-gen'', "to create".)
Physiology
Angiotensin II is thought to be a powerful dipsogen, and is one of the products of the reni ...
for ostriches. Both of these antidiuretic hormones work together to maintain water levels in the body that would normally be lost due to the osmotic stress of the arid environment.
Ostriches are uricotelic
Metabolic wastes or excrements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted. This includes nitrogen compounds, w ...
, excreting nitrogen in the form of uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown of ...
and related derivatives. Uric acid's low solubility in water gives a semi-solid paste consistency to the ostrich's nitrogenous waste.
Thermoregulation
Common ostriches are homeothermic
Homeothermy, homothermy or homoiothermy is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environmen ...
endotherm
An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inste ...
s; they regulate a constant body temperature via regulating their metabolic heat rate. They closely regulate their core body temperature, but their appendage
An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body.
In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...
s may be cooler in comparison as found with regulating species. The temperature of their beak, neck surfaces, lower legs, feet, and toes are regulated through heat exchange with the environment. Up to 40% of their produced metabolic heat is dissipated
In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. In a dissipative process, energy (internal, bulk flow kinetic, or system potential) transforms from an initial form to a ...
across these structures, which account for about 12% of their total surface area. Total evaporative water loss (TEWL) is statistically lower in the common ostrich than in membering ratites.
As ambient temperature increases, dry heat loss decreases, but evaporative heat loss increases because of increased respiration
Respiration may refer to:
Biology
* Cellular respiration, the process in which nutrients are converted into useful energy in a cell
** Anaerobic respiration, cellular respiration without oxygen
** Maintenance respiration, the amount of cellula ...
. As ostriches experience high ambient temperatures, circa , they become slightly hyperthermic; however, they can maintain a stable body temperature, around , for up to 8 hours in these conditions.[ When dehydrated, the common ostrich minimizes water loss, causing the body temperature to increase further.][ When the body heat is allowed to increase the ]temperature gradient
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degree ...
between the common ostrich and ambient heat is equilibrated.
Physical adaptations
Common ostriches have developed a comprehensive set of behavioral adaptations for thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
, such as altering their feathers. Common ostriches display a feather fluffing behavior that aids them in thermoregulation by regulating convective heat loss at high ambient temperatures. They may also physically seek out shade in times of high ambient temperatures. When feather fluffing, they contract their muscles to raise their feathers to increase the air space next to their skin. This air space provides an insulating thickness of . The ostrich will also expose the thermal windows of their unfeathered skin to enhance convective and radiative loss in times of heat stress. At higher ambient temperatures lower appendage temperature increases to difference from ambient temperature. Neck surfaces are around difference at most ambient temperatures, except when temperatures are around it was only above ambient.
At low ambient temperatures the common ostrich utilizes feather flattening, which conserves body heat through insulation. The low conductance coefficient of air allows less heat to be lost to the environment. This flattening behavior compensate for common ostrich's rather poor cutaneous evaporative water loss (CEWL). These feather-heavy areas such as the body, thighs, and wings do not usually vary much from ambient temperatures due to this behavioural controls. This ostrich will also cover its legs to reduce heat loss to the environment, along with undergoing piloerection
Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold or experiencing strong emotions such as fear, euphoria or sexual arousal.
The f ...
and shiver
Shivering (also called shuddering) is a bodily function in response to cold and extreme fear in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Skeletal muscles begin to s ...
ing when faced with low ambient temperatures.
Internal adaptations
The use of countercurrent heat exchange with blood flow allows for regulated conservation/ elimination of heat of appendages.[ When ambient temperatures are low, heterotherms will constrict their arterioles to reduce heat loss along skin surfaces.][ The reverse occurs at high ambient temperatures, arterioles ]dilate
Dilation (or dilatation) may refer to:
Physiology or medicine
* Cervical dilation, the widening of the cervix in childbirth, miscarriage etc.
* Coronary dilation, or coronary reflex
* Dilation and curettage, the opening of the cervix and surgic ...
to increase heat loss.[
At ambient temperatures below their body temperatures (]thermal neutral zone
Endothermic organisms known as homeotherms maintain internal temperatures with minimal metabolic regulation within a range of ambient temperatures called the thermal neutral zone (TNZ). Within the TNZ the basal rate of heat production is equal to ...
(TNZ)), common ostriches decrease body surface temperatures so that heat loss occurs only across about 10% of total surface area.[ This 10% include critical areas that require blood flow to remain high to prevent freezing, such as their eyes.][ Their eyes and ears tend to be the warmest regions.][ It has been found that temperatures of lower appendages were no more than above ambient temperature, which minimizes heat exchange between feet, toes, wings, and legs.][
Both the Gular and air sacs, being close to body temperature, are the main contributors to heat and water loss.][ Surface temperature can be affected by the rate of blood flow to a certain area and also by the surface area of the surrounding tissue.][ The ostrich reduces blood flow to the trachea to cool itself and vasodilates to its blood vessels around the gular region to raise the temperature of the tissue.][ The air sacs are poorly vascularized but show an increased temperature, which aids in heat loss.][
Common ostriches have evolved a 'selective brain cooling' mechanism as a means of thermoregulation. This modality allows the common ostrich to manage the temperature of the blood going to the brain in response to the extreme ]ambient temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
of the surroundings. The morphology for heat exchange occurs via cerebral arteries
The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain.
The three main arteries are the:
* ''Anterior cerebral artery'' (ACA)
* ''Middle cerebral artery'' (MCA)
* ''Posterior cereb ...
and the ophthalmic rete, a network of arteries originating from the ophthalmic artery
The ophthalmic artery (OA) is an artery of the head. It is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some st ...
. The ophthalmic rete is analogous
Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...
to the carotid rete found in mammals, as it also facilitates transfer of heat from arterial blood coming from the core to venous blood returning from the evaporative surfaces at the head.[
Researchers suggest that common ostriches also employ a 'selective brain warming' mechanism in response to cooler surrounding temperatures in the evenings. The brain was found to maintain a warmer temperature when compared to ]carotid
In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
arterial
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...
blood supply. Researchers hypothesize three mechanisms that could explain this finding:[
# They first suggest a possible increase in ]metabolic
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
heat production within the brain tissue itself to compensate for the colder arterial
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...
blood arriving from the core.
# They also speculate that there is an overall decrease in cerebral blood flow to the brain.
# Finally, they suggest that warm venous blood perfusion
Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is deliver ...
at the ophthalmic rete helps to warm the cerebral blood that supplies the hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
.
Further research will need to be done to find how this occurs.[
]
Breathing adaptations
The common ostrich has no sweat glands
Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...
, and under heat stress they rely on panting to reduce their body temperature.[ Panting increases evaporative heat (and water) loss from its respiratory surfaces, therefore forcing air and heat removal without the loss of metabolic salts.] Panting allows the common ostrich to have a very effective respiratory evaporative water loss (REWL). Heat dissipated by respiratory evaporation increases linearly with ambient temperature, matching the rate of heat production. As a result of panting the common ostrich should eventually experience alkalosis. However, The CO2 concentration in the blood does not change when hot ambient temperatures are experienced.[ This effect is caused by a lung surface shunt.][ The lung is not completely shunted, allowing enough oxygen to fulfill the bird's ]metabolic
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
needs.[ The common ostrich utilizes ]gular fluttering
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
, rapid rhythmic contraction and relaxation of throat muscles, in a similar way to panting. Both these behaviors allow the ostrich to actively increase the rate of evaporative cooling.
In hot temperatures water is lost via respiration. Moreover, varying surface temperatures within the respiratory tract contribute differently to overall heat and water loss through panting.[ The surface temperature of the gular area is , that of the tracheal area is between , and that of both anterior and posterior air sacs is .][ The long trachea, being cooler than body temperature, is a site of water evaporation.][
As ambient air becomes hotter, additional evaporation can take place lower in the trachea making its way to the posterior sacs, shunting the lung surface.][ The trachea acts as a buffer for evaporation because of the length and the controlled vascularization.] The Gular is also heavily vascularized; its purpose is for cooling blood, but also evaporation, as previously stated. Air flowing through the trachea can be either laminar
Laminar means "flat". Laminar may refer to:
Terms in science and engineering:
* Laminar electronics or organic electronics, a branch of material sciences dealing with electrically conductive polymers and small molecules
* Laminar armour or "band ...
or turbulent
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between t ...
depending on the state of the bird. When the common ostrich is breathing normally, under no heat stress, air flow is laminar.[ When the common ostrich is experiencing heat stress from the environment the air flow is considered turbulent.][ This suggests that laminar air flow causes little to no heat transfer, while under heat stress turbulent airflow can cause maximum heat transfer within the trachea.][
]
Metabolism
Common ostriches are able to attain their necessary energetic requirements via the oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
of absorbed nutrients. Much of the metabolic rate in animals is dependent upon their allometry
Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Julian Huxley in 1932.
Overview
Allom ...
, the relationship between body size to shape, anatomy, physiology, and behavior of an animal. Hence, it is plausible to state that metabolic rate in animals with larger masses is greater than animals with a smaller mass.
When a bird is inactive and unfed, and the ambient temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
(i.e. in the thermo-neutral zone) is high, the energy expended is at its minimum. This level of expenditure is better known as the basal metabolic rate (BMR), and can be calculated by measuring the amount of oxygen consumed during various activities.[ Therefore, in common ostriches we see use of more energy when compared to smaller birds in absolute terms, but less per unit mass.
A key point when looking at the common ostrich metabolism is to note that it is a non-passerine bird. Thus, BMR in ostriches is particularly low with a value of only 0.113 mL O2 g−1 h−1. This value can further be described using ]Kleiber's law
Kleiber's law, named after Max Kleiber for his biology work in the early 1930s, is the observation that, for the vast majority of animals, an animal's metabolic rate scales to the power of the animal's mass. Symbolically: if is the animal's metab ...
, which relates the BMR to the body mass of an animal.
:Metabolic rate = 70''M''0.75
where ''M'' is body mass, and metabolic rate is measured in kcal
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
per day.
In common ostriches, a BMR (mL O2 g−1 h−1) = 389 kg0.73, describing a line parallel to the intercept with only about 60% in relation to other non-passerine birds.[
Along with BMR, energy is also needed for a range of other activities. If the ]ambient temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
is lower than the thermo-neutral zone, heat is produced to maintain body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
.[ So, the metabolic rate in a resting, unfed bird, that is producing heat is known as the standard metabolic rate (SMR) or resting metabolic rate (RMR). The common ostrich SMR has been seen to be approximately 0.26 mL O2 g−1 h−1, almost 2.3 times the BMR.][ On another note, animals that engage in extensive physical activity employ substantial amounts of energy for power. This is known as the maximum metabolic scope. In an ostrich, it is seen to be at least 28 times greater than the BMR. Likewise, the daily energy ]turnover rate
Turnover or turn over may refer to:
Arts, entertainment, and media
*'' Turn Over'', a 1988 live album by Japanese band Show-Ya
*Turnover (band), an American rock band
*"Turnover", a song on Fugazi's 1990 album ''Repeater''
*''Turnover'', a Japanes ...
for an ostrich with access to free water is 12,700 kJ d−1, equivalent to 0.26 mL O2 g−1 h−1.[
]
Status and conservation
The wild common ostrich population has declined drastically in the last 200 years, with most surviving birds in reserves or on farms. However, its range remains very large (), leading the IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
and BirdLife International
BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...
to treat it as a species of Least Concern
A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
. Of its 5 subspecies, the Arabian ostrich
The Arabian ostrich (''Struthio camelus syriacus''), Syrian ostrich, or Middle Eastern ostrich is an extinct subspecies of the ostrich that lived on the Arabian Peninsula and in the Near East until the mid-20th century.
Distribution
Its range s ...
(''S. c. syriacus'') became extinct around 1966. North African ostrich populations are protected under Appendix I of the Convention on International Trade in Endangered Species
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
(CITES) meaning commercial international trade is prohibited and non-commercial trade is strictly regulated.
Humans
Common ostriches have inspired cultures and civilizations for 5,000 years in Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...
and Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
. A statue of Arsinoe II of Egypt
Arsinoë II ( grc-koi, Ἀρσινόη, 316 BC – unknown date between July 270 and 260 BC) was a Ptolemaic queen and co-regent of the Ptolemaic Kingdom of ancient Egypt. She was given the Egyptian title "King of Upper and Lower Egypt", making ...
riding a common ostrich was found in a tomb in Egypt.[ ]Hunter-gatherer
A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi, ...
s in the Kalahari
The Kalahari Desert is a large semi-arid sandy savanna in Southern Africa extending for , covering much of Botswana, and parts of Namibia and South Africa.
It is not to be confused with the Angolan, Namibian, and South African Namib coastal de ...
use ostrich eggshells as water containers, punching a hole in them. They also produce jewelry from it.[ The presence of such eggshells with engraved hatched symbols dating from the ]Howiesons Poort
Howiesons Poort (also called HP) is a lithic technology cultural period in the Middle Stone Age in Africa named after the Howieson's Poort Shelter archeological site near Grahamstown in South Africa. It seems to have lasted around 5,000 years betw ...
period of the Middle Stone Age
The Middle Stone Age (or MSA) was a period of African prehistory between the Early Stone Age and the Late Stone Age. It is generally considered to have begun around 280,000 years ago and ended around 50–25,000 years ago. The beginnings of pa ...
at Diepkloof Rock Shelter
Diepkloof Rock Shelter is a rock shelter in Western Cape, South Africa in which has been found some of the earliest evidence of the human use of symbols, in the form of patterns engraved upon ostrich eggshell water containers. These date arou ...
in South Africa suggests common ostriches were an important part of human life as early as 60,000 BP.
In Eastern Christianity
Eastern Christianity comprises Christian traditions and church families that originally developed during classical and late antiquity in Eastern Europe, Southeastern Europe, Asia Minor, the Caucasus, Northeast Africa, the Fertile Crescent and ...
it is common to hang decorated common ostrich eggs on the chains holding the oil lamps. The initial reason was probably to prevent mice and rats from climbing down the chain to eat the oil. Another, symbolical explanation is based in the fictitious tradition that female common ostriches do not sit on their eggs, but stare at them incessantly until they hatch out, because if they stop staring even for a second the egg will addle. This is equated to the obligation of the Christian to direct his entire attention towards God during prayer, lest the prayer be fruitless.
"Head in the sand" myth
Contrary to popular belief, ostriches do not bury their heads in sand to avoid danger.[ This myth likely began with ]Pliny the Elder
Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...
(23–79 CE), who wrote that ostriches "imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed."[ This may have been a misunderstanding of their sticking their heads in the sand to swallow sand and pebbles to help digest their fibrous food,][ or, as ]National Geographic
''National Geographic'' (formerly the ''National Geographic Magazine'', sometimes branded as NAT GEO) is a popular American monthly magazine published by National Geographic Partners. Known for its photojournalism, it is one of the most widely ...
suggests, of the defensive behavior of lying low, so that they may appear from a distance to have their head buried.[ Another possible origin for the myth lies with the fact that ostriches keep their eggs in holes in the sand instead of nests and must rotate them using their beaks during incubation; digging the hole, placing the eggs, and rotating them might each be mistaken for an attempt to bury their heads in the sand.]
Economic use
In Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
times, there was a demand for common ostriches to use in ''venatio
Venatio ( la, venatio, "hunting", plural ''venationes'') was a type of entertainment in Roman amphitheaters involving the hunting and killing of wild animals.
History
Venatio was first introduced by Marcus Fulvius Nobilior, who celebrated his G ...
'' games or cooking. They have been hunted and farmed for their feathers, which at various times have been popular for ornamentation in fashionable clothing (such as hats during the 19th century). Their skins are valued for their leather
Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, ...
. In the 18th century they were almost hunted to extinction; farming for feathers began in the 19th century. At the start of the 20th century there were over 700,000 birds in captivity.[ The market for feathers collapsed after ]World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, but commercial farming for feathers and later for skins and meat became widespread during the 1970s.
Common ostriches have been farmed in South Africa since the beginning of the 19th century. According to Frank G. Carpenter
Frank George Carpenter (May 8, 1855 in Mansfield, Ohio – June 18, 1924 in Nanking) was a journalist, traveler, travel writer, photographer, and lecturer. Carpenter was a writer of geography textbooks and lecturer on geography, and wrote a seri ...
, the English are credited with first taming common ostriches outside Cape Town
Cape Town ( af, Kaapstad; , xh, iKapa) is one of South Africa's three capital cities, serving as the seat of the Parliament of South Africa. It is the legislative capital of the country, the oldest city in the country, and the second largest ...
. Farmers captured baby common ostriches and raised them successfully on their property, and they were able to obtain a crop of feathers every seven to eight months instead of killing wild common ostriches for their feathers. It is claimed that common ostriches produce the strongest commercial leather.[ Common ostrich meat tastes similar to lean beef and is low in fat and ]cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
, as well as high in calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
, protein, and iron. It is considered to be both poultry and red meat
In gastronomy, red meat is commonly red when raw and a dark color after it is cooked, in contrast to white meat, which is pale in color before and after cooking. In culinary terms, only flesh from mammals or fowl (not fish) is classified as ...
. Uncooked, it is dark red or cherry red, a little darker than beef.[ ]Ostrich stew
Ostrich stew is a stew prepared using ostrich meat as a primary ingredient. It is a part of the South African cuisine, and is served in many places and restaurants in Oudtshoorn, South Africa. The meat can be diced into cubes, and leg meat from th ...
is a dish prepared using common ostrich meat.
Some common ostrich farms also cater to agri-tourism
Agritourism or agrotourism involves any agriculturally based operation or activity that brings visitors to a farm or ranch.
Types
A 2018 article published in the ''Journal of Agriculture, Food Systems, and Community Development'' classified a ...
, which may produce a substantial portion of the farm's income. This may include tours of the farmlands, souvenirs, or even ostrich rides.
Attacks
Common ostriches typically avoid humans in the wild, since they correctly assess humans as potential predators. If approached, they often run away, but sometimes ostriches can be very aggressive when threatened, especially if cornered, and may also attack if they feel the need to defend their territories or offspring. Similar behaviors are noted in captive or domesticated common ostriches, which retain the same natural instincts and can occasionally respond aggressively to stress. When attacking a person, common ostriches deliver slashing kicks with their powerful feet, armed with long claws, with which they can disembowel
Disembowelment or evisceration is the removal of some or all of the organs of the gastrointestinal tract (the bowels, or viscera), usually through a horizontal incision made across the abdominal area. Disembowelment may result from an accident ...
or kill a person with a single blow. In one study of common ostrich attacks, it was estimated that two to three attacks that result in serious injury or death occur each year in the area of Oudtshoorn
Oudtshoorn (, ), the "ostrich capital of the world", is a town in the Western Cape province of South Africa, located between the Swartberg mountains to the north and the Outeniqua Mountains to the south. Two ostrich-feather booms, during 1865–1 ...
, South Africa, where a large number of common ostrich farms are set next to both feral and wild common ostrich populations.
Racing
In some countries, people race each other on the backs of common ostriches. The practice is common in Africa and is relatively unusual elsewhere.[ The common ostriches are ridden in the same way as horses with special saddles, reins, and bits. However, they are harder to manage than horses.][ The practice is becoming less common due to ethical concerns, and nowadays ostrich farms set a limit weight for people to ride ostriches, making the activity mostly suited for children and smaller adults.
The racing is also a part of modern ]South African culture
South Africa is known for its ethnic and cultural diversity. Amongst black South Africans, a substantial number of rural inhabitants lead largely impoverished lives. Almost all South Africans speak English to some degree of proficiency, in add ...
.[ Within the United States, a ]tourist attraction
A tourist attraction is a place of interest that tourists visit, typically for its inherent or an exhibited natural or cultural value, historical significance, natural or built beauty, offering leisure and amusement.
Types
Places of natural b ...
in Jacksonville, Florida
Jacksonville is a city located on the Atlantic coast of northeast Florida, the most populous city proper in the state and is the largest city by area in the contiguous United States as of 2020. It is the seat of Duval County, with which the ...
, called 'The Ostrich Farm' opened up in 1892; it and its races became one of the most famous early attractions
Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. The World Tourism Organization defines tourism m ...
in the history of Florida
The history of Florida can be traced to when the first Native Americans began to inhabit the peninsula as early as 14,000 years ago. They left behind artifacts and archeological evidence. Florida's written history
Recorded history or writt ...
.[ Likewise, the arts scene in ]Indio, California
Indio (Spanish language, Spanish for "Indian") is a city in Riverside County, California, Riverside County, California, United States, in the Coachella Valley of Southern California's Colorado Desert region. It lies east of Palm Springs, Califo ...
, consists of both ostrich and camel racing
Camel racing is a popular sport in Western Asia, North Africa, the Horn of Africa, Pakistan, Mongolia and Australia. Professional camel racing, like horse racing, is an event for betting and tourist attraction. Camels can run at speeds up to ...
.
Chandler, Arizona
Chandler is a city in Maricopa County, Arizona, United States, and a suburb in the Phoenix-Mesa-Chandler Metropolitan Statistical Area (MSA). It is bordered to the north and west by Tempe, to the north by Mesa, to the west by Phoenix, to the ...
, hosts the annual "Ostrich Festival
Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are t ...
", which features common ostrich races.[ Racing has also occurred at many other locations such as ]Virginia City
Virginia City is a census-designated place (CDP) that is the county seat of Storey County, Nevada, and the largest community in the county. The city is a part of the Reno– Sparks Metropolitan Statistical Area.
Virginia City developed as a boom ...
in Nevada
Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
, Canterbury Park
Canterbury Park () (formerly Canterbury Downs), is a horse racing track in Shakopee, Minnesota, United States. Canterbury Park Holding Corporation ("Canterbury Park") hosts parimutuel wagering on live thoroughbred and quarter horse racing at ...
in Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
,[ ]Prairie Meadows
Prairie Meadows is a Thoroughbred and Quarter Horse racetrack casino located in Altoona, Iowa, United States.
History and information
In 1984, Prairie Meadows received a license from the Iowa Racing and Gaming commission to operate a horse racing ...
in Iowa
Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...
, Ellis Park in Kentucky
Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...
,[ and the ]Fairgrounds
Fairground most typically refers to a permanent space that hosts fairs.
Fairground, Fairgrounds, Fair Ground or Fair Grounds may also refer to:
Places
Canada
* Fairground, Ontario, a community
United States
* Fairground, St. Louis, a neighbor ...
in , Louisiana.
Notes
References
Further reading
*
*
*
External links
*
* (Common) Ostrich
Species text in The Atlas of Southern African Birds
British Domesticated Ostrich Association
World Ostrich Association
{{Authority control
common ostrich
The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members o ...
Domesticated birds
Flightless birds
Livestock
Ratites
Birds of Africa
Birds of Sub-Saharan Africa
Extant Miocene first appearances
common ostrich
The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members o ...
Articles containing video clips
common ostrich
The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members o ...
Ostriches