Horn (anatomy)

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A pair of horns on a male impala Male impala profile.jpg
A pair of horns on a male impala
Anatomy and physiology of an animal's horn Anatomy and physiology of animals A horn.jpg
Anatomy and physiology of an animal's 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 antlers, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls,[ not verified in body ] in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone. [1]

Contents

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, Manx Loaghtan, and the Navajo-Churro.

Horns usually have a curved or spiral shape, often with ridges or fluting. In many species, only males have horns. Horns start to grow soon after birth and continue to grow throughout the life of the animal (except in pronghorns, which shed the outer layer annually, but retain the bony core). Partial or deformed horns in livestock are called 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:

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 (Wild Boars), Proboscidea (Elephants), Monodontidae (Narwhals) 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. [4]

Cases of people growing horns have been historically described, sometimes with mythical status. Researchers have not however discovered photographic evidence of the phenomenon. [5] There are human cadaveric specimens that show outgrowings, but these are instead classified as osteomas or other excrescences. [5]

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. [6]

Some people, notably The Enigma, have horn implants; that is, they have implanted silicone beneath the skin as a form of body modification. [7]

Animal uses of horns

Goat skull piece Goat skull (MAV FMVZ USP).jpg
Goat skull piece
African buffalo (both sexes have horns) Serengeti Bueffel2.jpg
African buffalo (both sexes have 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. [8] [9] 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 savannahlike habitat are more likely to bear horns than small or camouflaged species. [10]

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.

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

Human uses of horns

Water buffalo horn used as a hammer with cleaver to cut fish in southeast China Water buffalo horn 01.JPG
Water buffalo horn used as a hammer with cleaver to cut fish in southeast China

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). [12] [13] [14] When the animal were to be poached, the animal is generally killed as it is shot first. Park rangers however may decide to tranquilize the animal instead to remove the horn.[ clarification needed ]

See also

Related Research Articles

Ungulate Group of animals that use the tips of their toes or hooves to walk on

Ungulates are members of a diverse clade of primarily large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses and tapirs, and even-toed ungulates such as cattle, pigs, giraffes, camels, sheep, deer, and hippopotamuses. Cetaceans are also even-toed ungulates, although they do not have hooves. Most terrestrial ungulates use the tips of their toes, usually hoofed, to support their body weight while moving.

Even-toed ungulate Order of mammals

The even-toed ungulates are ungulates—hoofed animals—which bear weight equally on two of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, odd-toed ungulates bear weight on an odd number of the five toes. Another difference between the two is that even-toed ungulates digest plant cellulose in one or more stomach chambers rather than in their intestine as the odd-toed ungulates do.

Antelope Term referring to an even-toed ruminant

The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia.

<i>Triceratops</i> Genus of ceratopsid dinosaur from the Late Cretaceous

Triceratops is an extinct genus of herbivorous 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 of the last-known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which literally means 'three-horned face', is derived from the Greek words trí- (τρί-) meaning 'three', kéras (κέρας) meaning 'horn', and ṓps (ὤψ) meaning 'face'.

Antler

Antlers are extensions of an animal's skull found in members of the deer family. Antlers are a single structure composed of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. They are generally found only on males, with the exception of the reindeer/caribou. Antlers are shed and regrown each year and function primarily as objects of sexual attraction and as weapons in fights between males for control of harems.

Shofar Wind instrument made from an animal horn

A shofar is an ancient musical horn typically made of a ram's horn, used for Jewish religious purposes. Like the modern bugle, the shofar lacks pitch-altering devices, with all pitch control done by varying the player's embouchure. The shofar is blown in synagogue services on Rosh Hashanah and at the end of Yom Kippur; it is also blown every weekday morning in the month of Elul running up to Rosh Hashanah. Shofars come in a variety of sizes and shapes, depending on the choice of animal and level of finish.

Bovidae A family of mammals belonging to even-toed ungulates

The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes bison, African buffalo, water buffalo, antelopes, sheep, goats, muskoxen, and domestic cattle. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, the family Bovidae consists of eight major subfamilies apart from the disputed Peleinae and Pantholopinae. The family evolved 20 million years ago, in the early Miocene.

Four-horned antelope Small antelope from Asia (Tetracerus quadricornis)

The four-horned antelope, or chousingha, is a small antelope found in India and Nepal. Its four horns distinguish it from most other bovids, which have two horns. The sole member of the genus Tetracerus, the species was first described by French zoologist Henri Marie Ducrotay de Blainville in 1816. Three subspecies are recognised. The four-horned antelope stands nearly 55–64 centimetres (22–25 in) at the shoulder and weighs nearly 17–22 kilograms (37–49 lb). Slender with thin legs and a short tail, the four-horned antelope has a yellowish brown to reddish coat. One pair of horns is located between the ears, and the other on the forehead. The posterior horns are always longer than the anterior horns, which might be mere fur-covered studs. While the posterior horns measure 8–12 centimetres (3.1–4.7 in), the anterior ones are 2–5 centimetres (0.79–1.97 in) long.

<i>Achelousaurus</i> Genus of ceratopsid dinosaur from North America

Achelousaurus is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 74.2 million years ago. The first fossils of Achelousaurus were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to the Greek deity Achelous, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults.

<i>Zuul</i> Genus of armored ankylosaurine dinosaurs

Zuul is a genus of herbivorous ankylosaurinae dinosaur from the Campanian Judith River Formation of Montana. The type species is Zuul crurivastator. It is known from a complete skull and tail, which represents the first ankylosaurin known from a complete skull and tail club, as well as the most complete ankylosaurid specimen thus far recovered from North America. The specimen also preserved in situ osteoderms, keratin, and skin remains.

Pecora Infraorder of mammals

Pecora is an infraorder of even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones; only two extant genera lack them, Hydropotes and Moschus. The name “Pecora” comes from the Latin word pecus, which means “horned livestock”. Although most pecorans have cranial appendages, only some of these are properly called “horns”, and many scientists agree that these appendages did not arise from a common ancestor, but instead evolved independently on at least two occasions. Likewise, while Pecora as a group is supported by both molecular and morphological studies, morphological support for interrelationships between pecoran families is disputed.

<i>Eobasileus</i>

Eobasileus cornutus was a prehistoric species of dinocerate mammal.

<i>Pelorovis</i> Extinct genus of cattle

Pelorovis is an extinct genus of African wild cattle, which first appeared in the very beginning of the Pleistocene, 2.5 million years ago, and became extinct at the end of the Late Pleistocene about 12,000 years ago or even during the Holocene, some 4,000 years ago.

Armour (anatomy)

Armour or armor in animals is external or superficial protection against attack by predators, formed as part of the body, usually through the hardening of body tissues, outgrowths or secretions. It has therefore mostly developed in 'prey' species.

Ossicone

Ossicones are columnar or conical skin-covered bone structures on the heads of giraffes, male okapi, and some of their extinct relatives. Ossicones are distinguished from the superficially similar structures of horns and antlers by their unique development and a permanent covering of skin and fur.

Brontotheriidae Extinct family of odd-toed ungulates

Brontotheriidae is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs. Superficially, they looked rather like rhinos, although they were actually more closely related to horses; Equidae and Brontotheriidae make up the suborder Hippomorpha. They lived around 56–34 million years ago, until the very close of the Eocene.

Conservation and restoration of bone, horn, and antler objects

Conservation-restoration of bone, horn, and antler objects involves the processes by which the deterioration of objects either containing or made from bone, horn, and antler is contained and prevented. Their use has been documented throughout history in many societal groups as these materials are durable, plentiful, versatile, and naturally occurring/replenishing.

<i>Shringasaurus</i> Genus of herbivorous Triassic horned reptile

Shringasaurus is an extinct genus of archosauromorph reptile from the Middle Triassic (Anisian) of India. It is known from the type and only known species, S. indicus. Shringasaurus is known from the Denwa Formation in the state of Madhya Pradesh. Shringasaurus was an allokotosaur, a group of unusual herbivorous reptiles from the Triassic, and is most closely related to the smaller and better known Azendohsaurus in the family Azendohsauridae. Like some ceratopsid dinosaurs, Shringasaurus had two large horns over its eyes that faced up and forwards from its skull. These horns were likely used for display, and possibly during fights with other Shringasaurus, much like what has been suggested for the horns of ceratopsids like Triceratops. Shringsaurus also bears similarities to sauropodomorph dinosaurs, such as its long neck and teeth, and likely occupied a similar ecological niche as a large browsing herbivore before they had evolved.

Evolution of domestic goats

Goat evolution is the process by which domestic goats came to exist through evolution by natural selection. Wild goats were one of the first species domesticated by modern humans, with the date of domestication generally considered to be 8,000 BCE. Domestic goats are medium-sized mammals which are found in noticeably harsh environments, particularly forest and mountains, in the Middle east and Central Asia, covering an area from Turkey to Turkmenistan. Goats are part of the family Bovidae, a broad and populous group which includes a variety of ruminants such as bison, cows and sheep. Bovids all share many traits, such as hooves and a herbivorous diet and all males, along with many females, have horns. Bovids began to diverge from deer and giraffids during the early Miocene epoch. The subfamily Caprinae, which includes goats, ibex and sheep, are considered to have diverged from the other bovidae as early as the late Miocene, with the group reaching its greatest diversity in the ice ages.

References

  1. Nasoori, Alireza (2020). "Formation, structure, and function of extra‐skeletal bones in mammals" (PDF). Biological Reviews. 95 (4): 986–1019. doi:10.1111/brv.12597. PMID   32338826. S2CID   216556342.
  2. Sketches of the natural history of Ceylon by Sir James Emerson Tennent, published by Longman, Green, Longman, and Roberts, 1861
  3. Mammals of Nepal: (with reference to those of India, Bangladesh, Bhutan and Pakistan) by Tej Kumar Shrestha, published by Steven Simpson Books, 1997, ISBN   0-9524390-6-9
  4. Alston, Isabella (2014-08-01). Anatomical Anomalies. TAJ Books International. ISBN   9781844063789.
  5. 1 2 Tubbs, R. Shane; Smyth, Matthew D.; Wellons, John C. III; Blount, Jeffrey P.; Oakes, W. Jerry (June 2003). "Human horns: a historical review and clinical correlation". Neurosurgery. 52 (6): 1443–1448. doi:10.1227/01.NEU.0000064810.08577.49. PMID   12762889. S2CID   24254020. (Literature Reviews)
  6. "Bundestagswahl 2013". Archived from [DEAD LINK! http://www.stern.de/wissen/mensch/ungewoehnliche-operation-aerzte-befreien-frau-von-horn-1682189.html the original] Check |url= value (help) on 2011-05-09.
  7. Johann, Hari (2002-03-11). "Johann Hari on the bizarre world of radical plastic surgery". London: Guardian News and Media. Retrieved 2010-05-04.
  8. Valerius Geist; Fritz R. Walther; International Union for Conservation of Nature and Natural Resources (1974). The Behaviour of Ungulates and Its Relation to Management: The Papers of an International Symposium Held at the University of Calgary, Alberta, Canada, 2-5 November 1971. International Union for Conservation of Nature and Natural Resources.
  9. Edward O. Wilson (1 January 1980). Sociobiology. Harvard University Press. pp. 119–. ISBN   978-0-674-81624-4.)
  10. "Why Female Water Buffalo Have Horns but Impala Do Not?".
  11. Chusid, Hearing Shofar: The Still Small Voice of the Ram's Horn, 2009, Chapter 3-6 - Ram's Horn of Passover <http://www.hearingshofar.com Archived 2010-03-28 at the Wayback Machine >. The book also posits that the ancient Hebrews and neighboring tribes used horns as weapons and as utensils.
  12. Cutting off horns to save rhinos from poachers
  13. Cutting off horns to save rhinos from poachers
  14. Dehorning rhinos