Steller's sea cow (''Hydrodamalis gigas'') is an
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
sirenia
The Sirenia (), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct famili ...
n described by
Georg Wilhelm Steller in 1741. At that time, it was found only around the
Commander Islands
The Commander Islands, Komandorski Islands, or Komandorskie Islands (, ''Komandorskiye ostrova'') are a series of islands in the Russian Far East, a part of the Aleutian Islands, located about east of the Kamchatka Peninsula in the Bering Sea. ...
in the
Bering Sea
The Bering Sea ( , ; rus, Бе́рингово мо́ре, r=Béringovo móre, p=ˈbʲerʲɪnɡəvə ˈmorʲe) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasse ...
between
Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
and
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
; its range extended across the North Pacific during the
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
epoch
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided b ...
, and likely contracted to such an extreme degree due to the
glacial cycle
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and gr ...
. It is possible that indigenous populations interacted with the animal before Europeans. Steller first encountered it on
Vitus Bering
Vitus Jonassen Bering ( , , ; baptised 5 August 1681 – 19 December 1741),All dates are here given in the Julian calendar, which was in use throughout Russia at the time. also known as Ivan Ivanovich Bering (), was a Danish-born Russia ...
's
Great Northern Expedition when the crew became shipwrecked on
Bering Island
Bering Island () is located off the Kamchatka Peninsula in the Bering Sea.
Description
At long by wide, it is the largest and westernmost of the Commander Islands, with an area of . Most of Bering Island and several of the smaller islands in ...
. Much of what is known about its behavior comes from Steller's observations on the island, documented in his posthumous publication ''On the Beasts of the Sea''. Within 27 years of its discovery by Europeans, the slow-moving and easily-caught mammal was hunted into extinction for its meat, fat, and hide.
Some 18th-century adults would have reached weights of and lengths up to . It was a member of the family
Dugongidae
Dugongidae is a Family (biology), family in the Order (biology), order of Sirenia. The family has one surviving species, the dugong (''Dugong dugon''), one recently Extinction, extinct species, Steller's sea cow (''Hydrodamalis gigas''), and a n ...
, of which the long
dugong
The dugong (; ''Dugong dugon'') is a marine mammal. It is one of four living species of the order Sirenia, which also includes three species of manatees. It is the only living representative of the once-diverse family Dugongidae; its closest ...
(''Dugong dugon'') is the sole living member. It had a thicker layer of
blubber
Blubber is a thick layer of Blood vessel, vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians. It was present in many marine reptiles, such as Ichthyosauria, ichthyosaurs and plesiosaurs.
Description ...
than other members of the order, an adaptation to the cold waters of its environment. Its tail was forked, like that of whales or dugongs. Lacking true teeth, it had an array of white bristles on its upper lip and two
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...
ous plates within its mouth for chewing. It fed mainly on
kelp
Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...
, and communicated with sighs and snorting sounds. Steller believed it was a
monogamous
Monogamy ( ) is a relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...
and
social animal
Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies.
Sociality is a survival response to evolutionary pressures. For example, when a mother was ...
living in small family groups and
raising its young, similar to modern sirenians.
Description
Steller's sea cows are reported to have grown to long as adults, much larger than
extant
Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Exta ...
sirenia
The Sirenia (), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct famili ...
ns.
In 1987, a rather complete skeleton was found on Bering Island measuring . In 2017, another such skeleton was found on Bering Island measuring , and in life probably about .
Georg Steller's writings contain two contradictory estimates of weight: . The true value is estimated to fall between these figures, at about . This size made the sea cow one of the largest mammals of the
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
epoch
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided b ...
, along with baleen whales and some few toothed whales,
[ and was likely an adaptation to reduce its surface-area to volume ratio and conserve heat.][
Unlike other sirenians, Steller's sea cow was positively ]buoyant
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
, meaning that it was unable to submerge completely. It had a very thick outer skin, , to prevent injury from sharp rocks and ice and possibly to prevent unsubmerged skin from drying out.[ The sea cow's ]blubber
Blubber is a thick layer of Blood vessel, vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians. It was present in many marine reptiles, such as Ichthyosauria, ichthyosaurs and plesiosaurs.
Description ...
was thick, another adaptation to the frigid climate of the Bering Sea. Its skin was brownish-black, with white patches on some individuals. It was smooth along its back and rough on its sides, with crater-like depressions most likely caused by parasite
Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s. This rough texture led to the animal being nicknamed the "bark animal". Hair on its body was sparse, but the insides of the sea cow's flippers were covered in bristles.[ The fore limbs were roughly long, and the tail fluke was forked.][
The sea cow's head was small and short in comparison to its huge body. The animal's upper lip was large and broad, extending so far beyond the ]lower jaw
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
that the mouth appeared to be located underneath the skull. Unlike other sirenians, Steller's sea cow was toothless and instead had a dense array of interlacing white bristles on its upper lip. The bristles were about in length and were used to tear seaweed
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...
stalks and hold food.[ The sea cow also had two ]keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...
ous plates, called ceratodontes, located on its 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 sep ...
and mandible
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
, used for chewing. According to Steller, these plates (or "masticatory pads") were held together by interdental papilla
The interdental papilla, also known as the interdental gingiva, is the part of the gums (gingiva) that exists coronal to the free gingival margin on the mesial and distal surfaces of the teeth. The interdental papillae fill in the area betw ...
e, a part of the gums
The gums or gingiva (: gingivae) consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue lining of the ...
, and had many small holes containing nerve
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...
s and arteries
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
.[
]
As with all sirenians, the sea cow's snout
A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...
pointed downwards, which allowed it to better grasp kelp
Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...
. The sea cow's nostrils were roughly long and wide. In addition to those within its mouth, the sea cow also had stiff bristles long protruding from its muzzle.[ Steller's sea cow had small eyes located halfway between its nostrils and ears with black irises, livid eyeballs, and ]canthi
The canthus (: canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure.
The ...
which were not externally visible. The animal had no eyelashes, but like other diving creatures such as sea otter
The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern Pacific Ocean, North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of ...
s, Steller's sea cow had a nictitating membrane
The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. Most ...
, which covered its eyes to prevent injury while feeding. The tongue was small and remained in the back of the mouth, unable to reach the masticatory (chewing) pads.
The sea cow's spine is believed to have had seven cervical (neck), 17 thoracic
The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of 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 ...
, three lumbar
In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm (anatomy), diaphragm and the sacrum.
Naming and location
The lumbar region is sometimes referred to as the lowe ...
, and 34 caudal (tail) vertebrae. Its ribs were large, with five of 17 pairs making contact with the sternum
The sternum (: sternums or sterna) 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 bl ...
; it had no clavicle
The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...
s.[ As in all sirenians, the ]scapula
The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...
of Steller's sea cow was fan-shaped, being larger on the posterior side and narrower towards the neck. The anterior border of the scapula was nearly straight, whereas those of modern sirenians are curved. Like other sirenians, the bones of Steller's sea cow were pachyosteosclerotic, meaning they were both bulky ( pachyostotic) and dense ( osteosclerotic). In all collected skeletons of the sea cow, the manus is missing; since '' Dusisiren''—the sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
of '' Hydrodamalis''—had reduced phalanges
The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...
(finger bones), Steller's sea cow possibly did not have a manus at all.
The sea cow's heart was in weight; its stomach measured long and wide. The full length of its intestinal tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...
was about , equaling more than 20 times the animal's length. The sea cow had no gallbladder
In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow Organ (anatomy), organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath t ...
, but did have a wide common bile duct
The common bile duct (also bile duct) is a part of the biliary tract. It is formed by the union of the common hepatic duct and cystic duct. It ends by uniting with the pancreatic duct to form the ampulla of Vater (hepatopancreatic ampulla). ...
. Its anus was in width, with its feces
Feces (also known as faeces American and British English spelling differences#ae and oe, or fæces; : faex) 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 ...
resembling those of horses. The male's penis was long.[ Genetic evidence indicates ]convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
with other marine mammals of genes related to metabolic and immune function, including leptin
Leptin (from Ancient Greek, Greek λεπτός ''leptos'', "thin" or "light" or "small"), also known as obese protein, is a protein hormone predominantly made by adipocytes (cells of adipose tissue). Its primary role is likely to regulate long ...
associated with energy homeostasis
In biology, homeostasis (British English, British also homoeostasis; ) is the state of steady internal physics, physical and chemistry, chemical conditions maintained by organism, living systems. This is the condition of optimal functioning fo ...
and reproductive regulation.
Ecology and behavior
Whether Steller's sea cow had any natural predators
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
is unknown. It may have been hunted by killer whale
The orca (''Orcinus orca''), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. The only extant species in the genus '' Orcinus'', it is recognizable by its black-and-white-patterned body. A cosmopolit ...
s and shark
Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
s, though its buoyancy may have made it difficult for killer whales to drown, and the rocky kelp forest
Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on E ...
s in which the sea cow lived may have deterred sharks. According to Steller, the adults guarded the young from predators.[
Steller described an ]ectoparasite
Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
on the sea cows that was similar to the whale louse (''Cyamus ovalis''), but the parasite remains unidentified due to the host
A host is a person responsible for guests at an event or for providing hospitality during it.
Host may also refer to:
Places
* Host, Pennsylvania, a village in Berks County
* Host Island, in the Wilhelm Archipelago, Antarctica
People
* ...
's extinction and loss of all original specimens collected by Steller. It was first formally described as ''Sirenocyamus rhytinae'' in 1846 by Johann Friedrich von Brandt
Johann Friedrich von Brandt (25 May 1802 – 15 July 1879) was a German-Russian natural history, naturalist, who worked mostly in Russia.
Brandt was born in Jüterbog and educated at a Gymnasium (school), gymnasium in Wittenberg and the Humboldt ...
, although it has since been placed into the genus '' Cyamus'' as '' Cyamus rhytinae''. It was the only species of cyamid amphipod
Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...
to be reported inhabiting a sirenian. Steller also identified an endoparasite
Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...
in the sea cows, which was likely an ascarid nematode.[
Like other sirenians, Steller's sea cow was an obligate ]herbivore
A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...
and spent most of the day feeding, only lifting its head every 4–5 minutes for breathing.[ Kelp was its main food source, making it an algivore. The sea cow likely fed on several species of kelp, which have been identified as '' Agarum'' spp., '' Alaria praelonga'', '' Halosaccion glandiforme'', '' Laminaria saccharina'', '' Nereocyctis luetkeana'', and '' Thalassiophyllum clathrus''. Steller's sea cow only fed directly on the soft parts of the kelp, which caused the tougher stem and holdfast to wash up on the shore in heaps. The sea cow may have also fed on ]seagrass
Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...
, but the plant was not common enough to support a viable population and could not have been the sea cow's primary food source. Further, the available seagrasses in the sea cow's range ('' Phyllospadix'' spp. and '' Zostera marina'') may have grown too deep underwater or been too tough for the animal to consume. Since the sea cow floated, it likely fed on canopy
Canopy may refer to:
Plants
* Canopy (biology), aboveground portion of plant community or crop (including forests)
* Canopy (grape), aboveground portion of grapes
Religion and ceremonies
* Baldachin or canopy of state, typically placed over an a ...
kelp, as it is believed to have only had access to food no deeper than below the tide. Kelp releases a chemical deterrent to protect it from grazing, but canopy kelp releases a lower concentration of the chemical, allowing the sea cow to graze safely.[ Steller noted that the sea cow grew thin during the frigid winters, indicating a period of ]fasting
Fasting is the act of refraining from eating, and sometimes drinking. However, from a purely physiological context, "fasting" may refer to the metabolic status of a person who has not eaten overnight (before "breakfast"), or to the metabolic sta ...
due to low kelp growth.[ Fossils of ]Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
Aleutian Island sea cow populations were larger than those from the Commander Islands, indicating that the growth of Commander Island sea cows may have been stunted due to a less favorable habitat and less food than the warmer Aleutian Islands.[
Steller described the sea cow as being highly social (]gregarious
Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies.
Sociality is a survival response to evolutionary pressures. For example, when a mother was ...
). It lived in small family groups and helped injured members, and was also apparently monogamous
Monogamy ( ) is a relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...
. Steller's sea cow may have exhibited parental care
Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal k ...
, and the young were kept at the front of the herd for protection against predators. Steller reported that as a female was being captured, a group of other sea cows attacked the hunting boat by ramming and rocking it, and after the hunt, her mate followed the boat to shore, even after the captured animal had died. Mating season occurred in early spring and gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...
took a little over a year, with calves likely delivered in autumn, as Steller observed a greater number of calves in autumn than at any other time of the year. Since female sea cows had only one set of mammary gland
A mammary gland is an exocrine gland that produces milk in humans and other mammals. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, human ...
s, they likely had one calf at a time.[
The sea cow used its fore limbs for swimming, feeding, walking in shallow water, defending itself, and holding on to its partner during copulation.][ According to Steller, the fore limbs were also used to anchor the sea cow down to prevent it from being swept away by the strong nearshore waves.][ While grazing, the sea cow progressed slowly by moving its tail (fluke) from side to side; more rapid movement was achieved by strong vertical beating of the tail. They often slept on their backs after feeding. According to Steller, the sea cow was nearly mute and made only heavy breathing sounds, raspy snorting similar to a horse, and sighs.][
Despite their large size, as with many other marine megafauna in the region, Steller's sea cows may have been prey for the local transient orcas (''Orcinus orca''); it is likely that they experienced predation, as Steller observed that foraging sea cows with calves would always keep their calves between themselves and the shore, and orcas would have been the most likely candidate for causing this behavior. In addition, early ]indigenous peoples
There is no generally accepted definition of Indigenous peoples, although in the 21st century the focus has been on self-identification, cultural difference from other groups in a state, a special relationship with their traditional territ ...
of the North Pacific may have depended on the sea cow for food, and it is possible that this dependency may have extirpated
Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.
Local extinctions mark a chan ...
the sea cow from portions of the North Pacific aside from the Commander Islands. Steller's sea cows may have also had a mutualistic (or possibly even parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...
) relationship with local seabird
Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...
species; Steller often observed birds perching on the exposed backs of the sea cows, feeding on the parasitic ''Cyamus rhytinae''; this unique relationship that disappeared with the sea cows may have been a food source for many birds, and is similar to the recorded interactions between oxpeckers (''Buphagus'') and extant African megafauna.
Taxonomy
Phylogeny
Steller's sea cow was a member of the genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
'' Hydrodamalis'', a group of large sirenians, whose sister taxon was '' Dusisiren''. Like those of Steller's sea cow, the ancestors of ''Dusisiren'' lived in tropical mangrove
A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...
s before adapting to the cold climates of the North Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the contine ...
. ''Hydrodamalis'' and ''Dusisiren'' are classified together in the subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
Hydrodamalinae, which diverged from other sirenians around 4 to 8 mya. Steller's sea cow is a member of the family Dugongidae
Dugongidae is a Family (biology), family in the Order (biology), order of Sirenia. The family has one surviving species, the dugong (''Dugong dugon''), one recently Extinction, extinct species, Steller's sea cow (''Hydrodamalis gigas''), and a n ...
, the sole surviving member of which, and thus Steller's sea cow's closest living relative is the dugong
The dugong (; ''Dugong dugon'') is a marine mammal. It is one of four living species of the order Sirenia, which also includes three species of manatees. It is the only living representative of the once-diverse family Dugongidae; its closest ...
(''Dugong dugon'').
Steller's sea cow was a direct descendant of the Cuesta sea cow (''H. cuestae''),[ an extinct tropical sea cow that lived off the coast of western North America, particularly California. The Cuesta sea cow is thought to have become extinct due to the onset of the ]Quaternary glaciation
The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial period, glacial and interglacial, interglacial periods during the Quaternary period that began 2.58 Year#SI prefix multipliers, Ma (million ...
and the subsequent cooling of the oceans. Many populations died out, but the lineage of Steller's sea cow was able to adapt to the colder temperatures. The Takikawa sea cow (''H. spissa'') of Japan is thought of by some researchers to be a taxonomic synonym
In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The Botanical nomenclature, botanical and Zoological nomenclature, zoological codes of nomencl ...
of the Cuesta sea cow, but based on a comparison of endocasts, the Takikawa and Steller's sea cows are more derived than the Cuesta sea cow. This has led some to believe that the Takikawa sea cow is its own species.[ The evolution of the genus ''Hydrodamalis'' was characterized by increased size, and a loss of teeth and ]phalanges
The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...
, as a response to the onset of the Quaternary glaciation.[
]
Research history
Steller's sea cow was discovered in 1741 by Georg Wilhelm Steller, and was named after him. Steller researched the wildlife of Bering Island
Bering Island () is located off the Kamchatka Peninsula in the Bering Sea.
Description
At long by wide, it is the largest and westernmost of the Commander Islands, with an area of . Most of Bering Island and several of the smaller islands in ...
while he was shipwrecked there for about a year; the animals on the island included relict
A relict is a surviving remnant of a natural phenomenon.
Biology
A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas.
Geology and geomorphology
In geology, a r ...
populations of sea cows, sea otters, Steller sea lion
The Steller sea lion (''Eumetopias jubatus''), also known as Steller's sea lion or the northern sea lion, is a large, near-threatened species of sea lion, predominantly found in the coastal marine habitats of the northeast Pacific Ocean and th ...
s, and northern fur seal
The northern fur seal (''Callorhinus ursinus'') is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only living species in the ...
s. As the crew hunted the animals to survive, Steller described them in detail. Steller's account was included in his posthumous publication ''De bestiis marinis'', or ''The Beasts of the Sea'', which was published in 1751 by the Russian Academy of Sciences
The Russian Academy of Sciences (RAS; ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such ...
in Saint Petersburg
Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...
. Zoologist Eberhard von Zimmermann formally described Steller's sea cow in 1780 as ''Manati gigas''. Biologist Anders Jahan Retzius in 1794 put the sea cow in the new genus ''Hydrodamalis'', with the specific name of ''stelleri'', in honor of Steller.[ In 1811, naturalist ]Johann Karl Wilhelm Illiger
Johann Karl Wilhelm Illiger (19 November 1775 – 10 May 1813) was a German entomologist and zoologist. He founded the entomological periodical ''Magazin für Insektenkunde.'' The plant genus '' Illigera'' is named in his honour.
Biography
Illi ...
reclassified Steller's sea cow into the genus ''Rytina'', which many writers at the time adopted. The name ''Hydrodamalis gigas'', the correct ''combinatio nova
In biological taxonomy, a combinatio nova (abbreviated comb. nov. or n. comb.) refers to the formal renaming of an organism's scientific name when it is transferred to a different genus, reclassified within a different species, or its taxonomic ...
'' if a separate genus is recognised, was first used in 1895 by Theodore Sherman Palmer.[
]
For decades after its discovery, no skeletal remains of a Steller's sea cow were known.[ This may have been due to rising and falling sea levels over the course of the Quaternary period, which could have left many sea cow bones hidden.][ The first bones of a Steller's sea cow were unearthed in about 1840, over 70 years after it was presumed to have become extinct. The first partial sea cow skull was discovered in 1844 by Ilya Voznesensky while on the Commander Islands, and the first skeleton was discovered in 1855 on northern Bering Island. These specimens were sent to Saint Petersburg in 1857, and another nearly complete skeleton arrived in Moscow around 1860. Until recently, all the full skeletons were found during the 19th century, being the most productive period in terms of unearthed skeletal remains, from 1878 to 1883. During this time, 12 of the 22 skeletons having known dates of collection were discovered. Some authors did not believe possible the recovery of further significant skeletal material from the Commander Islands after this period, but a skeleton was found in 1983, and two zoologists collected about 90 bones in 1991.] Only two to four skeletons of the sea cow exhibited in various museums of the world originate from a single individual. It is known that Adolf Erik Nordenskiöld
Nils Adolf Erik Nordenskiöld (; 18 November 183212 August 1901) was a Finland-Swedish aristocrat, geologist, mineralogist and Arctic explorer. He was a member of the noble Nordenskiöld family of scientists and held the title of a friherre (ba ...
, Benedykt Dybowski
Benedykt Tadeusz Dybowski (12 May 183331 January 1930) was a Polish naturalist and physician.
Life
Benedykt Dybowski was born in Adamaryni, within the Minsk Governorate of the Russian Empire to Polish nobility. He was the brother of naturalis ...
, and Leonhard Hess Stejneger
Leonhard Hess Stejneger (30 October 1851 – 28 February 1943) was a Norwegian-born American ornithologist, herpetologist and zoologist. Stejneger specialized in vertebrate natural history studies. He gained his greatest reputation with reptile ...
unearthed many skeletal remains from different individuals in the late 1800s, from which composite skeletons were assembled. As of 2006, 27 nearly complete skeletons and 62 complete skulls have been found, but most of them are assemblages of bones from two to 16 different individuals.
Illustrations
The Pallas Picture is the only known drawing of Steller's sea cow believed to be from a complete specimen. It was published by Peter Simon Pallas
Peter Simon Pallas Fellow of the Royal Society, FRS FRSE (22 September 1741 – 8 September 1811) was a Prussia, Prussian zoologist, botanist, Ethnography, ethnographer, Exploration, explorer, Geography, geographer, Geology, geologist, Natura ...
in his 1840 work . Pallas did not specify a source; Stejneger suggested it may have been one of the original illustrations produced by Friedrich Plenisner, a member of Vitus Bering
Vitus Jonassen Bering ( , , ; baptised 5 August 1681 – 19 December 1741),All dates are here given in the Julian calendar, which was in use throughout Russia at the time. also known as Ivan Ivanovich Bering (), was a Danish-born Russia ...
's crew as a painter and surveyor who drew a figure of a female sea cow on Steller's request. Most of Plenisner's depictions were lost during transit from Siberia to Saint Petersburg.[
Another drawing of Steller's sea cow similar to the Pallas Picture appeared on a 1744 map drawn by Sven Waxell and Sofron Chitrow. The picture may have also been based upon a specimen, and was published in 1893 by Pekarski. The map depicted Vitus Bering's route during the Great Northern Expedition, and featured illustrations of Steller's sea cow and Steller's sea lion in the upper-left corner. The drawing contains some inaccurate features such as the inclusion of eyelids and fingers, leading to doubt that it was drawn from a specimen.][
]Johann Friedrich von Brandt
Johann Friedrich von Brandt (25 May 1802 – 15 July 1879) was a German-Russian natural history, naturalist, who worked mostly in Russia.
Brandt was born in Jüterbog and educated at a Gymnasium (school), gymnasium in Wittenberg and the Humboldt ...
, director of the Russian Academy of Sciences, had the "Ideal Image" drawn in 1846 based upon the Pallas Picture, and then the "Ideal Picture" in 1868 based upon collected skeletons. Two other possible drawings of Steller's sea cow were found in 1891 in Waxell's manuscript diary. There was a map depicting a sea cow, as well as a Steller sea lion and a northern fur seal. The sea cow was depicted with large eyes, a large head, claw-like hands, exaggerated folds on the body, and a tail fluke in perspective lying horizontally rather than vertically. The drawing may have been a distorted depiction of a juvenile, as the figure bears a resemblance to a manatee
Manatees (, family (biology), family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivory, herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing t ...
calf. Another similar image was found by Alexander von Middendorff
Alexander Theodor von Middendorff (; 18 August 1815 – 24 January 1894) was a Russian zoologist and explorer of Baltic German and Estonian extraction. He was known for his expedition in 1843–45 to the extreme north and east of Siberia, des ...
in 1867 in the library of the Russian Academy of Sciences, and is probably a copy of the Tsarskoye Selo Picture.
Range
The range of Steller's sea cow at the time of its discovery was apparently restricted to the shallow seas around the Commander Islands
The Commander Islands, Komandorski Islands, or Komandorskie Islands (, ''Komandorskiye ostrova'') are a series of islands in the Russian Far East, a part of the Aleutian Islands, located about east of the Kamchatka Peninsula in the Bering Sea. ...
, which include Bering and Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
Islands.[ The Commander Islands remained uninhabited until 1825, when the ]Russian-American Company
The Russian-American Company Under the High Patronage of His Imperial Majesty was a state-sponsored chartered company formed largely on the basis of the Shelikhov-Golikov Company, United American Company. Emperor Paul I of Russia chartered the c ...
relocated Aleut
Aleuts ( ; (west) or (east) ) are the Indigenous people of the Aleutian Islands, which are located between the North Pacific Ocean and the Bering Sea. Both the Aleuts and the islands are politically divided between the US state of Alaska ...
s from Attu Island
Attu (, ) is an island in the Near Islands (part of the Aleutian Islands chain). It is one of the westernmost points of the U.S. state of Alaska. The island became uninhabited in 2010, making it the largest uninhabited island that is part of th ...
and Atka Island there.
The first fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
s discovered outside the Commander Islands were found in interglacial
An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...
Pleistocene deposits in Amchitka,[ and further fossils dating to the late Pleistocene were found in ]Monterey Bay
Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles (120 km), accessible via California S ...
, California, and Honshu
, historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...
, Japan. This suggests that the sea cow had a far more extensive range in prehistoric times, but the possibility that these fossils belong to other ''Hydrodamalis'' species cannot be excluded. The southernmost find is a Middle Pleistocene
The Chibanian, more widely known as the Middle Pleistocene (its previous informal name), is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocen ...
rib bone from the Bōsō Peninsula
The is a peninsula that encompasses the entirety of Chiba Prefecture on Honshu, the largest island of Japan. It is part of the Greater Tokyo Area. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean. The peninsula covers ...
of Japan. The remains of three individuals were found preserved in the South Bight Formation of Amchitka; as late Pleistocene interglacial deposits are rare in the Aleutians, the discovery suggests that sea cows were abundant during that era. According to Steller, the sea cow often resided in the shallow, sandy shorelines and in the mouths of freshwater rivers.[ Genetic evidence suggests that Steller's sea cow, as well as the modern dugong, suffered a ]population bottleneck
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, wid ...
(a significant reduction in population) bottoming roughly 400,000 years ago.[
Bone fragments and accounts by native Aleut people suggest that sea cows also historically inhabited the ]Near Islands
The Near Islands or the Sasignan Islands (, ) are a group of volcanic islands in the Aleutian Islands in southwestern Alaska, between the Russian Commander Islands to the west and Buldir Island and the Rat Islands to the east.
Geography
Th ...
, possibly with viable populations that were in contact with humans in the western Aleutian Islands
The Aleutian Islands ( ; ; , "land of the Aleuts"; possibly from the Chukchi language, Chukchi ''aliat'', or "island")—also called the Aleut Islands, Aleutic Islands, or, before Alaska Purchase, 1867, the Catherine Archipelago—are a chain ...
prior to Steller's discovery in 1741. A sea cow rib discovered in 1998 on Kiska Island
Kiska (, ) is one of the Rat Islands, a group of the Aleutian Islands of Alaska. It is about long and varies in width from . It is part of Aleutian Islands Wilderness and as such, special permission is required to visit it. The island ha ...
was dated to around 1,000 years old, and is now in the possession of the Burke Museum
The Burke Museum of Natural History and Culture (commonly as Burke Museum) is a natural history museum on the campus of the University of Washington, in Seattle, Washington (state), Washington, United States. It is administered by the University ...
in Seattle; the dating may be skewed due to the marine reservoir effect, which causes radiocarbon-dated marine specimens to appear several hundred years older than they are. (Marine reservoir effect is caused by the large reserves of C14 in the ocean, and it is more likely that the animal died between 1710 and 1785. A 2004 study reported that sea cow bones discovered on Adak Island were around 1,700 years old, and sea cow bones discovered on Buldir Island were found to be around 1,600 years old. It is possible that these bones were from cetaceans and were misclassified.[ Rib bones of a Steller's sea cow have also been found on St. Lawrence Island, from a specimen that is thought to have lived between 800 and 920 CE.]
Interactions with humans
Extinction
Genetic evidence suggests the Steller's sea cows around the Commander Islands were the last of a much more ubiquitous population dispersed across the North Pacific coastal zones. They had the same genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
as the last and rather inbred
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders an ...
population of woolly mammoth
The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived from the Middle Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with the African ...
s on Wrangel Island
Wrangel Island (, ; , , ) is an island of the Chukotka Autonomous Okrug, Russia. It is the List of islands by area, 92nd-largest island in the world and roughly the size of Crete. Located in the Arctic Ocean between the Chukchi Sea and East Si ...
. During glacial periods and reduction in sea levels and temperatures, suitable habitat substantially regressed, fragmenting the population. By the time sea levels stabilized around 5,000 years ago, the population had already plummeted. Together, these indicate that even without human influence, the Steller's sea cow would have still been a dead clade walking, with the vast majority of the population having already gone extinct from natural climatic and sea level shifts, with the tiny remaining population at major risk from a genetic extinction vortex
Extinction vortices are a class of models through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. This model shows the events that ultimately lea ...
.[
]
The presence of Steller's sea cows in the Aleutian Islands may have caused the Aleut people to migrate westward to hunt them. This possibly led to the sea cow's extirpation in that area, assuming it had not already happened yet, but the archaeological evidence is inconclusive. One factor potentially leading to extinction of Steller's sea cow, specifically off the coast of St. Lawrence Island, was the Siberian Yupik people who have inhabited St. Lawrence island for 2,000 years. They may have hunted the sea cows into extinction, as the natives have a dietary culture heavily dependent upon marine mammal
Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine enviro ...
s. The onset of the Medieval Warm Period
The Medieval Warm Period (MWP), also known as the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warm climate in the North Atlantic region that lasted from about to about . Climate proxy records show peak warmth occu ...
, which reduced the availability of kelp, may have also been the cause for their local extinction
Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with extinction, global extinctions.
Local extinctions ...
in that area.[ It has also been argued that the decline of Steller's sea cow may have been an indirect effect of the harvesting of sea otters by the area's aboriginal people. With the otter population reduced, the ]sea urchin
Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...
population would have increased, in turn reducing the stock of kelp, its principal food.[ In historic times, though, aboriginal hunting had depleted sea otter populations only in localized areas,][ and as the sea cow would have been easy prey for aboriginal hunters, accessible populations may have been exterminated with or without simultaneous otter hunting. In any event, the range of the sea cow was limited to coastal areas off uninhabited islands by the time Bering arrived, and the animal was already ]endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
.
When Europeans discovered them, there may have been only 2,000 individuals left.[ This small population was quickly wiped out by ]fur trade
The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal ecosystem, boreal, polar and cold temperate mammalian animals h ...
rs, seal hunters, and others who followed Vitus Bering's route past its habitat to Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
. It was also hunted to collect its valuable subcutaneous fat
The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and ...
. The animal was hunted and used by Ivan Krassilnikov in 1754 and Ivan Korovin 1762, but Dimitri Bragin, in 1772, and others later, did not see it. Brandt thus concluded that by 1768, twenty-seven years after it had been discovered by Europeans, the species was extinct. In 1887, Stejneger estimated that there had been fewer than 1,500 individuals remaining at the time of Steller's discovery, and argued there was already an immediate danger of the sea cow's extinction.[
The first attempt to hunt the animal by Steller and the other crew members was unsuccessful due to its strength and thick hide. They had attempted to impale it and haul it to shore using a large hook and heavy cable, but the crew could not pierce its skin. In a second attempt a month later, a ]harpoon
A harpoon is a long, spear-like projectile used in fishing, whaling, sealing, and other hunting to shoot, kill, and capture large fish or marine mammals such as seals, sea cows, and whales. It impales the target and secures it with barb or ...
er speared an animal, and men on shore hauled it in while others repeatedly stabbed it with bayonet
A bayonet (from Old French , now spelt ) is a -4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ... , now spelt ) is a knife, dagger">knife">-4; we might wonder whethe ...
s. It was dragged into shallow waters, and the crew waited until the tide receded and it was beached to butcher it.[ After this, they were hunted with relative ease, the challenge being in hauling the animal back to shore. This bounty inspired maritime fur traders to detour to the Commander Islands and restock their food supplies during North Pacific expeditions.][
]
Impact of extinction
While not a keystone species
A keystone species is a species that has a disproportionately large effect on its natural environment relative to its abundance. The concept was introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in main ...
, Steller's sea cows likely influenced the community composition of the kelp forest
Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on E ...
s they inhabited, and also boosted their productivity
Productivity is the efficiency of production of goods or services expressed by some measure. Measurements of productivity are often expressed as a ratio of an aggregate output to a single input or an aggregate input used in a production proce ...
and resilience to environmental stressors by allowing more light into kelp forests and more kelp to grow, and enhancing the recruitment
Recruitment is #Process, the overall process of identifying, sourcing, screening, shortlisting, and interviewing candidates for Job (role), jobs (either permanent or temporary) within an organization. Recruitment also is the process involved in ...
and dispersal of kelp through their feeding behavior. In the modern day, the flow of nutrients from kelp forests to adjacent ecosystems is regulated by the seasons, with seasonal storms and currents being the primary factor. The Steller's sea cow may have allowed this flow to continue year-round, thus allowing for more productivity in adjacent habitats. The disturbance caused by the Steller's sea cow may have facilitated the dispersal of kelp, most notably ''Nereocystis
''Nereocystis'' (Greek, 'mermaid's bladder') is a monotypic genus of subtidal kelp containing the species ''Nereocystis luetkeana''. Some English names include edible kelp, bull kelp, bullwhip kelp, ribbon kelp, bladder wrack, and variations of ...
'' species, to other habitats, allowing recruitment and colonization
475px, Map of the year each country achieved List of sovereign states by date of formation, independence.
Colonization (British English: colonisation) is a process of establishing occupation of or control over foreign territories or peoples f ...
of new areas, and facilitating genetic exchange. Their presence may have also allowed sea otter
The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern Pacific Ocean, North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of ...
s and large marine invertebrates
Marine invertebrates are invertebrate animals that live in marine habitats, and make up most of the macroscopic life in the oceans. It is a polyphyletic blanket term that contains all marine animals except the marine vertebrates, including the ...
to coexist, indicating a commonly-documented decline in marine invertebrate populations driven by sea otters (an example being in populations of the black leather chiton) may be due to lost ecosystem functions associated with the Steller's sea cow. This indicates that due to the sea cow's extinction, the ecosystem dynamics and resilience of North Pacific kelp forests may have already been compromised well before more well-known modern stressors like overharvesting
Overexploitation, also called overharvesting or ecological overshoot, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to ...
and climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
.
Later reported sightings
Sea cow sightings have been reported after Brandt's official 1768 date of extinction. Lucien Turner, an American ethnologist
Ethnology (from the , meaning 'nation') is an academic field and discipline that compares and analyzes the characteristics of different peoples and the relationships between them (compare cultural, social, or sociocultural anthropology).
Scien ...
and naturalist, said the natives of Attu Island
Attu (, ) is an island in the Near Islands (part of the Aleutian Islands chain). It is one of the westernmost points of the U.S. state of Alaska. The island became uninhabited in 2010, making it the largest uninhabited island that is part of th ...
reported that the sea cows survived into the 1800s, and were sometimes hunted.[
In 1963, the official journal of the ]Academy of Sciences of the USSR
The Academy of Sciences of the Soviet Union was the highest scientific institution of the Soviet Union from 1925 to 1991. It united the country's leading scientists and was subordinated directly to the Council of Ministers of the Soviet Union (u ...
published an article announcing a possible sighting. The previous year, the whaling ship
A whaler or whaling ship is a specialized vessel, designed or adapted for whaling: the catching or processing of whales.
Terminology
The term ''whaler'' is mostly historic. A handful of nations continue with industrial whaling, and one, Jap ...
''Buran'' had reported a group of large marine mammals grazing on seaweed in shallow water off Kamchatka
The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively.
Immediately offshore along the Pacific ...
, in the Gulf of Anadyr
The Gulf of Anadyr, or Anadyr Bay (), is a large bay on the Bering Sea in far northeast Siberia. It has a total surface area of
Location
The bay is roughly rectangular and opens to the southeast. The corners are (clockwise from the south) Cape ...
. The crew reported seeing six of these animals ranging from , with trunks and split lips. There have also been alleged sightings by local fishermen in the northern Kuril Islands
The Kuril Islands or Kurile Islands are a volcanic archipelago administered as part of Sakhalin Oblast in the Russian Far East. The islands stretch approximately northeast from Hokkaido in Japan to Kamchatka Peninsula in Russia, separating the ...
, and around the Kamchatka and Chukchi peninsulas.
Uses
Steller's sea cow was described as being "tasty" by Steller; the meat was said to have a taste similar to corned beef, though it was tougher, redder, and needed to be cooked longer. The meat was abundant on the animal, and slow to spoil, perhaps due to the high amount of salt in the animal's diet effectively curing it. The fat could be used for cooking and as an odorless lamp oil. The crew of the St. Peter drank the fat in cups and Steller described it as having a taste like almond oil
The almond (''Prunus amygdalus'', syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera by corrugations on the sh ...
. The thick, sweet milk of female sea cows could be drunk or made into butter
Butter is a dairy product made from the fat and protein components of Churning (butter), churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 81% butterfat. It is used at room temperature as a spread (food ...
,[ and the thick, leathery hide could be used to make clothing, such as shoes and belts, and large skin boats sometimes called ]baidarka
The baidarka or Aleutian kayak (Aleut: iqyax) is a watercraft consisting of soft skin (artificial or natural) over a flexible space frame. Without primarily vertical flex, it is not an ''iqyax''. Its initial design was created by the Aleut peo ...
s or umiaks.
Towards the end of the 19th century, bones and fossils from the extinct animal were valuable and often sold to museums at high prices. Most were collected during this time, limiting trade after 1900.[ Some are still sold commercially, as the highly dense ]cortical bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...
is well-suited for making items such as knife handles and decorative carvings.[ Because the sea cow is extinct, native artisan products made in Alaska from this "mermaid ivory" are legal to sell in the United States and do not fall under the jurisdiction of the Marine Mammal Protection Act (MMPA) or the (CITES), which restrict the trade of marine mammal products. Although the distribution is legal, the sale of unfossilized bones is generally prohibited and trade in products made of the bones is regulated because some of the material is unlikely to be authentic and probably comes from arctic cetaceans.][
The ]ethnographer
Ethnography is a branch of anthropology and the systematic study of individual cultures. It explores cultural phenomena from the point of view of the subject of the study. Ethnography is also a type of social research that involves examining ...
Elizabeth Porfirevna Orlova, from the Russian Museum of Ethnography, was working on the Commander Island Aleuts from August to September 1961. Her research includes notes about a game of accuracy, called ''kakan'' ("stones") played with the bones of the Steller's sea cow. Kakan was usually played at home between adults during bad weather, at least during Orlova's fieldwork.
In literature, media, and folklore
In the story ''The White Seal'' from ''The Jungle Book
''The Jungle Book'' is an 1894 collection of stories by the English author Rudyard Kipling. Most of the characters are animals such as Shere Khan the tiger and Baloo the bear, though a principal character is the boy or "man-cub" Mowgli, who ...
'' by Rudyard Kipling
Joseph Rudyard Kipling ( ; 30 December 1865 – 18 January 1936)''The Times'', (London) 18 January 1936, p. 12. was an English journalist, novelist, poet, and short-story writer. He was born in British Raj, British India, which inspired much ...
, which takes place in the Bering Sea, Kotick the rare white
White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wa ...
seal
Seal may refer to any of the following:
Common uses
* Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly:
** Earless seal, also called "true seal"
** Fur seal
** Eared seal
* Seal ( ...
consults Sea Cow during his journey to find a new home.
''Tales of a Sea Cow'' is a 2012 docufiction
Docufiction (or docu-fiction) is the cinematographic combination of documentary film, documentary and fiction, this term often meaning narrative film. It is a film genre which attempts to capture reality such as it is (as direct cinema or ciné ...
film by Icelandic-French artist Etienne de France about a fictional 2006 discovery of Steller's sea cows off the coast of Greenland
Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
. The film has been exhibited in art museums and universities in Europe.
Steller's sea cows appear in two books of poetry: '' Nach der Natur'' (1995) by Winfried Georg Sebald, and '' Species Evanescens'' (2009) by Russian poet Andrei Bronnikov. Bronnikov's book depicts the events of the Great Northern Expedition through the eyes of Steller; Sebald's book looks at the conflict between man and nature, including the extinction of Steller's sea cow.
The novel '' Elolliset'' (Living things) (2023) by Finnish author and literary scholar Iida Turpeinen uses Steller's sea cow and its demise as a central theme. It features multiple characters at different times in history that were involved with the animal, beginning from Steller’s expedition and telling how the complete skeleton was conserved and ended up in the Helsinki museum of natural history.
Scottish poet John Glenday published the poem "The Kelp Eaters" in his 2003 volume, Grain, describing the beauty and loving nature of the sea cows and their harpooning by the narrator and his companions. The poem carries the epigraph "From “Journal of a Voyage with Bering 1741-1742” By Georg Wilhelm Steller".
Genetic research and potential revival
In 2021, the nuclear genome
Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. It ...
of the species was sequenced from skeletal remains. The reconstructed genome showed that the species was already declining due to low genetic diversity caused by climate change and hunting by Paleolithic
The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehist ...
humans prior to its discovery by Steller, similar to the final populations of woolly mammoths on Wrangel Island
Wrangel Island (, ; , , ) is an island of the Chukotka Autonomous Okrug, Russia. It is the List of islands by area, 92nd-largest island in the world and roughly the size of Crete. Located in the Arctic Ocean between the Chukchi Sea and East Si ...
. A year later, in late 2022, a group of Russian scientists funded by Sergi Bachin began research to potentially revive the species and reintroduce it to the Bering Sea. Arctic Sirenia plans to revive the species through genome editing
Genome editing, or genome engineering, or gene editing, is a type of genetic engineering in which DNA is inserted, deleted, modified or replaced in the genome of a living organism. Unlike early genetic engineering techniques that randomly insert ge ...
of the dugong, but an artificial womb is necessary to conceive a living sea cow due to the lack of an appropriate living surrogate species. Ben Lamm of Colossal Biosciences has also stated that he and his company want to revive the species after they complete their first four projects (woolly mammoth
The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived from the Middle Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with the African ...
, dodo
The dodo (''Raphus cucullatus'') is an extinction, extinct flightless bird that was endemism, endemic to the island of Mauritius, which is east of Madagascar in the Indian Ocean. The dodo's closest relative was the also-extinct and flightles ...
, thylacine
The thylacine (; binomial name ''Thylacinus cynocephalus''), also commonly known as the Tasmanian tiger or Tasmanian wolf, was a carnivorous marsupial that was native to the Mainland Australia, Australian mainland and the islands of Tasmani ...
, and northern white rhinoceros
The northern white rhinoceros or northern white rhino (''Ceratotherium simum cottoni'') is one of two subspecies of the white rhinoceros (the other being the southern white rhinoceros). This subspecies is a grazer in grasslands and savanna wood ...
) and have an artificial animal womb developed.
See also
* Holocene extinction
The Holocene extinction, also referred to as the Anthropocene extinction or the sixth mass extinction, is an ongoing extinction event caused exclusively by human activities during the Holocene epoch. This extinction event spans numerous families ...
* List of extinct animals of North America
* List of Asian animals extinct in the Holocene
* List of recently extinct mammals
Recently extinct mammals are defined by the International Union for Conservation of Nature (IUCN) as any mammals that have become extinct since the year 1500 CE. Since then, roughly 80 mammal species have become extinct.
Extinction of taxa ...
* Evolution of sirenians
Sirenia is the order (biology), order of Eutheria, placental mammals which comprises modern "sea cows" (manatees and the Dugong) and their extinct relatives. They are the only extant herbivorous marine mammals and the only group of herbivorous ...
* Cuesta sea cow
* Takikawa sea cow
References
Further reading
*
*
External links
Animal Diversity Web
Steller's sea cow information from the BBC
{{Authority control
Hydrodamalis
Extinct mammals of North America
Extinct mammals of Asia
Species made extinct by human activities
Pleistocene sirenians
Mammal extinctions since 1500
Sirenians
Mammals described in 1780
Taxa named by Eberhard August Wilhelm von Zimmermann
Commander Islands
Extinct animals of Russia
Extinct animals of the United States
Fossil taxa described in 1840
Species that are or were threatened by human consumption
Species that are or were threatened by use as food
Species that are or were threatened by use in wearables