Anatomy and physiology of animals A horn

A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from

antler Antlers are extensions of an animal's skull found in members of the Cervidae (deer) family. Antlers are a single structure composed of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. They are generally found only on male ...

s, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae ( pronghorn) and Bovidae ( cattle, goats,

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 ...

etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone. One pair of horns is usual; however, two or more pairs occur in a few wild species and in some domesticated breeds of sheep. Polycerate (multi-horned) sheep breeds include the

Hebridean The Hebrides (; gd, Innse Gall, ; non, Suðreyjar, "southern isles") are an archipelago off the west coast of the Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner Hebrides, Inner a ...

, Icelandic, Jacob, Manx Loaghtan, and the Navajo-Churro. Horns usually have a curved or

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:scurs. Similar growths on other parts of the body are not usually called horns, but spurs, claws, or hooves, depending on the part of the body on which they occur.

Other hornlike growths

The term "horn" is also popularly applied to other hard and pointed features attached to the head of animals in various other families: * Giraffidae:

Giraffe The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, ''Giraffa camelopardalis ...

s have one or more pairs of bony bumps on their heads, called ossicones. These are covered with furred skin. * Cervidae: Most deer have

s, which are not true horns and made of bone. When fully developed, antlers are dead bone without a horn or skin covering; they are borne only by adults (usually males, except for reindeer) and are shed and regrown each year. *

Rhinocerotidae A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species ...

: The "horns" of rhinoceroses are made of keratin, the same substance as fingernails, and grow continuously, but do not have a bone core. * Chamaeleonidae: Many chameleons, most notably the Jackson's chameleon, possess horns on their skulls, and have a keratin covering. * Ceratopsidae: The "horns" of the '' Triceratops'' were extensions of its skull bones, although debate exists over whether they had a keratin covering. * Abelisauridae: Various abelisaurid theropods, such as '' Carnotaurus'' and '' Majungasaurus'' possessed extensions of the frontal bone which were likely covered in some form of keratinous integument. * Horned lizards (''Phrynosoma''): These lizards have horns on their heads which have a hard keratin covering over a bony core, like mammalian horns. * Insects: Some insects (such as rhinoceros beetles) have hornlike structures on the head or thorax (or both). These are pointed outgrowths of the hard

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

ous exoskeleton. Some (such as

stag beetle Stag beetles are a family of about 1,200 species of beetles in the family Lucanidae, currently classified in four subfamilies.Smith, A.B.T. (2006). A review of the family-group names for the superfamily Scarabaeoidea (Coleoptera) with corrections ...

s) have greatly enlarged jaws, also made of chitin. *

Canidae Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within th ...

: Golden jackals are known to occasionally develop a horny growth on the skull, which is associated with magical powers in south-eastern Asia. * Azendohsauridae: the skull of the triassic azendohsaurid archosauromorph ''

Shringasaurus ''Shringasaurus'' (meaning "horned lizard", from Sanskrit शृङ्ग (''śṛṅga),'' "horn", and Ancient Greek (''sauros),'' "lizard") is an extinct genus of archosauromorph reptile from the Middle Triassic (Anisian) of India. It is known ...

'' possessed two massive, forward-facing conical horns, which were likely covered in cornified sheaths in life. * Anhimidae: The horned screamer possesses an entirely keratinous spine, which is loosely connected to its skull. Many mammal species in various families have tusks, which often serve the same functions as horns, but are in fact oversized teeth. These include the Moschidae (Musk deer, which are ruminants),

Suidae Suidae is a family of artiodactyl mammals which are commonly called pigs, hogs or swine. In addition to numerous fossil species, 18 extant species are currently recognized (or 19 counting domestic pigs and wild boars separately), classified into ...

( Wild Boars),

Proboscidea The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...

( Elephants), Monodontidae (

Narwhal The narwhal, also known as a narwhale (''Monodon monoceros''), is a medium-sized toothed whale that possesses a large "tusk" from a protruding canine tooth. It lives year-round in the Arctic waters around Greenland, Canada and Russia. It is o ...

s) and Odobenidae ( Walruses). Polled animals or ''pollards'' are those of normally-horned (mainly domesticated) species whose horns have been removed, or which have not grown. In some cases such animals have small horny growths in the skin where their horns would be – these are known as ''scurs''.

On humans

Cutaneous horns are the only examples of horns growing on people. Cases of people growing horns have been historically described, sometimes with mythical status. Researchers have not however discovered photographic evidence of the phenomenon. (''Literature Reviews'') There are human cadaveric specimens that show outgrowings, but these are instead classified as osteomas or other excrescences. The phenomenon of humans with horns has been observed in countries lacking advanced medicine. There are living people, several in China, with cases of cutaneous horns, most common in the elderly. Some people, notably The Enigma, have horn implants; that is, they have implanted silicone beneath the skin as a form of body modification.

Animal uses of horns

Animals have a variety of uses for horns and antlers, including defending themselves from predators and fighting members of their own species (''horn fighting'') for territory, dominance or mating priority. Horns are usually present only in males but in some species, females too may possess horns. It has been theorized by researchers that taller species living in the open are more visible from longer distances and more likely to benefit from horns to defend themselves against predators. Female bovids that are not hidden from predators due to their large size or open

savannah 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 (forest), canopy does not close. The open canopy allows sufficient light to rea ...

like habitat are more likely to bear horns than small or camouflaged species. In addition, horns may be used to root in the soil or strip bark from trees. In animal courtship many use horns in displays. For example, the male blue wildebeest reams the bark and branches of trees to impress the female and lure her into his territory. Some animals with true horns use them for cooling. The blood vessels in the bony core allow the horns to function as a

radiator Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics. A radiator is always a ...

. After the death of a horned animal, the keratin may be consumed by the larvae of the

horn moth ''Ceratophaga vastella'', or the horn moth, belongs to the clothes moth family Tineidae and is noted for its larva's ability to feed on keratin from the horns and hooves of dead ungulates, and occasionally on dried fruit or mushrooms. Keratin, a ...

Human uses of horns

*Horned animals are sometimes hunted so their mounted head or horns can be displayed as a

hunting trophy Trophy hunting is a form of hunting for sport in which parts of the hunted wild animals are kept and displayed as trophies. The animal being targeted, known as the " game", is typically a mature male specimen from a popular species of collectable ...

or as decorative objects. *Some cultures use bovid horns as

musical instrument A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person who pl ...

s, for example, the shofar. These have evolved into

brass instrument A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips. Brass instruments are also called labrosones or labrophones, from Latin a ...

s in which, unlike the trumpet, the bore gradually increases in width through most of its length—that is to say, it is conical rather than cylindrical. These are called horns, though now made of metal. * Drinking horns are bovid horns removed from the bone core, cleaned, polished, and used as

drinking vessel file:Drinkware.jpg , upTypical drinkware The list of glassware includes drinking vessels (drinkware) and tableware used to set a table for eating a meal, general glass items such as vases, and glasses used in the catering industry. It does not incl ...

s. (This is similar to the legend of the cornucopia.) It has been suggested that the shape of a natural horn was also the model for the rhyton, a horn-shaped drinking vessel. * Powder horns were originally bovid horns fitted with lids and carrying straps, used to carry gunpowder. Powder flasks of any material may be referred to as powder horns. *

Shoehorn A shoehorn or shoe horn (sometimes called a shoespooner, shoe spoon, shoe schlipp, or shoe tongue) is a tool with a short handle that flares into a longer spoon-like head meant to be held against the inside back of a snug-fitting shoe so that a ...

s were originally made from slices of bovid horn, which provided the right curving shape and a smooth surface. *Antelope horns are used in traditional Chinese medicine. *Horns consist of keratin, and the term "horn" is used to refer to this material, sometimes including similarly solid keratin from other parts of animals, such as hoofs. Horn may be used as a material in tools,

furniture Furniture refers to movable objects intended to support various human activities such as seating (e.g., stools, chairs, and sofas), eating (tables), storing items, eating and/or working with an item, and sleeping (e.g., beds and hammocks). Fu ...

and decoration, among other uses. In these applications, horn is valued for its hardness, and it has given rise to the expression ''hard as horn''. Horn is somewhat thermoplastic and (like tortoiseshell) was formerly used for many purposes where plastic would now be used. Horn may be used to make

glue Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

. * Horn bows are bows made from a combination of horn,

sinew A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

and usually wood. These materials allow more energy to be stored in a short bow than wood alone. *Horns and horn tips from various animals have been used for centuries in the manufacture of scales, grips, or handles for knives and other weapons, and beginning in the 19th century, for the handle scales of

handgun A handgun is a short- barrelled gun, typically a firearm, that is designed to be usable with only one hand. It is distinguished from a long gun (i.e. rifle, shotgun or machine gun, etc.), which needs to be held by both hands and also braced ...

s. *Horn buttons may be made from horns, and historically also hooves which are a similar material. The non-bony part of the horn or hoof may be softened by heating to a temperature just above the boiling point of water, then molded in metal dies, or the hollow lower part of the horn may be slit spirally lengthwise and then flattened in a vise between wood boards, again after heating, and later cut with a holesaw or similar tool into round or other shaped blanks which are finished on a lathe or by hand. Toggle buttons are made by cutting off the solid tips of horns and perforating them. Antler buttons, and buttons made from hooves are not technically horn buttons, but are often referred to as such in popular parlance. Horns from cattle, water buffalo, and sheep are all used for commercial button making, and of other species as well, on a local and non-commercial basis. *Horn combs were common in the era before replacement by plastic, and are still made. *Horn needle cases and other small boxes, particularly of water buffalo horn, are still made. One occasionally finds horn used as a material in antique snuff boxes. *Horn strips for inlaying wood are a traditional technique. *Carved horn hairpins and other jewelry such as brooches and rings are manufactured, particularly in Asia, including for the souvenir trade. *Horn is used in artwork for small, detailed carvings. It is an easily worked and polished material, is strong and durable, and in the right variety, beautiful. *Horn chopsticks are found in Asian countries from highland Nepal and Tibet to the Pacific coast. Typically they are not the common material, but rather are higher quality decorative articles. Similarly other horn flatware, notably spoons, continues to be manufactured for decorations and other purposes. * Long dice made of horn that have a rodlike elongated shape with four numbered faces and two small unnumbered end faces continue to be manufactured in Asia where they are traditionally used in games like Chaupar (Pachisi) and many others. *Horn is sometimes a material found in walking sticks, cane handles and shafts. In the latter use, the horn elements may be cut into short cylindrical segments held together by a metal core. * Several horned deities are represented with horns. * Horned helmets have been present in different cultures. They are thought mostly having been used for ritual purposes rather than combat. *Horns were treated and cut into strips to make semi-transparent windows in Medieval times.

Dehorning

In some instances, wildlife parks may decide to remove the horn of some animals (such as rhinos) as a preventive measure against poaching. Animal horns can be safely sawn off without hurting the animal (it is similar to clipping toe nails).Dehorning rhinos
/ref> When the animal were to be poached, the animal is generally killed as it is shot first.

Park ranger A ranger, park ranger, park warden, or forest ranger is a law enforcement person entrusted with protecting and preserving parklands – national, state, provincial, or local parks. Description "Parks" may be broadly defined by some systems in thi ...

s however may decide to tranquilize the animal instead to remove the horn.

Gallery

File:Erkencho del norte.jpg, Erkencho, musical instrument made from a horn File:The three-horned one again.jpg, A Hebridean sheep with one horn on one side and two on the other File:Water buffalo horn (Bubalus bubalis).jpg, Water buffalo horn (''Bubalus bubalis'') File:Elizabeth Bonté Art Nouveau horn necklace.jpg, Elizabeth Bonté

Art Nouveau Art Nouveau (; ) is an international style of art, architecture, and applied art, especially the decorative arts. The style is known by different names in different languages: in German, in Italian, in Catalan, and also known as the Modern ...

horn necklace File:Hippotragus niger mounted horns.jpg, Sable antelope mounted horns, at the Zoological Museum, Denmark File:Horns in museum.jpg, Horns, tusks and antlers in the

National Museum of Scotland The National Museum of Scotland in Edinburgh, Scotland, was formed in 2006 with the merger of the new Museum of Scotland, with collections relating to Scottish antiquities, culture and history, and the adjacent Royal Scottish Museum (opened in ...

References

External links

A site with information about the history of the cow horn as a musical instrument.
*MacGregor, Arthur. ''Bone, Antler, Ivory & Horn: The Technology of Skeletal Materials Since the Roman Period''. Barnes and Noble, 1985. eprinted 2016, RoutledgeThis is a scholarly monograph on the subject of horn and other skeletal materials, heavily illustrated, and with extensive academic and art-historical references. {{DEFAULTSORT:Horn (Anatomy) Animal anatomy Mammal anatomy Insect anatomy Amphibian anatomy Reptile anatomy Bird anatomy Animal products Dinosaur anatomy