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 Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up Scale (anatomy), scales, hair, Nail ...

and other

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s surrounding a core of live

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, ...

. 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 ...

s, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls, in the families

Antilocapridae The Antilocapridae are a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids with which they comprise the superfamily Giraffoidea. Only one species, the pronghorn (''Antilocapra americana''), is ...

( pronghorn) and

Bovidae The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, t ...

(

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...

goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...

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 mamm ...

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, Icelandic,

Jacob Jacob (; ; ar, يَعْقُوب, Yaʿqūb; gr, Ἰακώβ, Iakṓb), later given the name Israel, is regarded as a patriarch of the Israelites and is an important figure in Abrahamic religions, such as Judaism, Christianity, and Islam. ...

, 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 The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rumi ...

, 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 The Giraffidae are a family of ruminant artiodactyl mammals that share a common ancestor with deer and bovids. This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant genera, the giraffe (o ...

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 camelopardal ...

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 Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subs ...

) 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

, 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 ''Triceratops'' ( ; ) is a genus of herbivorous chasmosaurine ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the Late Cretaceous period, about 68 million years ago in what is now North America. It is one ...

'' 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 The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, ...

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. *

Insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s: Some insects (such as rhinoceros beetles) have hornlike structures on the head or

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the c ...

(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 An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...

. 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 withi ...

: 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 know ...

'' 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 Moschidae is a family of pecoran even-toed ungulates, containing the musk deer (''Moschus'') and its extinct relatives. They are characterized by long 'saber teeth' instead of horns, antlers or ossicones, modest size (''Moschus'' only reaches ; o ...

(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 in ...

(

Wild Boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species i ...

s),

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. Fr ...

(

Elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantida ...

s), 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 ...

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 does not close. The open canopy allows sufficient light to reach the ground to ...

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 Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...

many use horns in displays. For example, the male

blue wildebeest The blue wildebeest (''Connochaetes taurinus''), also called the common wildebeest, white-bearded gnu or brindled gnu, is a large antelope and one of the two species of wildebeest. It is placed in the genus '' Connochaetes'' and family Bovidae, a ...

reams the bark and branches of trees to impress the female and lure her into his

territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

. 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 ...

. 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, ...

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 trumpet is a brass instrument commonly used in classical and jazz ensembles. The trumpet group ranges from the piccolo trumpet—with the highest register in the brass family—to the bass trumpet, pitched one octave below the standard ...

, 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 A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...

. * Drinking horns are bovid horns removed from the bone core, cleaned, polished, and used as

drinking vessel 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 include laboratory glas ...

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 rhyton (plural rhytons or, following the Greek plural, rhyta) is a roughly conical container from which fluids were intended to be drunk or to be poured in some ceremony such as libation, or merely at table. A rhyton is typically formed in t ...

, a horn-shaped drinking vessel. *

Powder horn A powder horn is a container for gunpowder, and was generally created from cow, ox or buffalo horn. The term may also be used for any personal container for gunpowder, although powder flask is the strictly correct term. Features Typically t ...

s were originally bovid horns fitted with lids and carrying straps, used to carry

gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...

. 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

, 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) ...

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 A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

and (like tortoiseshell) was formerly used for many purposes where

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adapta ...

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 ag ...

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 (opene ...

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