Horn (anatomy)

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Highland cow, a very old long-horned breed from Scotland.

A horn is a hollow, pointed projection of the skin of various animals, consisting mainly of keratin as well as other proteins. True horns are found only among the ruminant artiodactyls, in the families Antilocapridae (pronghorn) and Bovidae (cows, buffalo, yaks, goats, antelope etc.). Those animals have one or two pairs of horns, which usually have a spiral shape.

The term is popularly applied also to any hard and pointed elements attached to the head of animals in various other families:

Giraffidae: Giraffes have bony bumps covered with furred skin which look like they ought to have horns on them, but do not.
Cervidae: Deer have antlers, which are not true horns. Made of bone, they are shed and regrown each year.
Rhinocerotidae: The "horns" of the Rhinoceros are made of keratin but are actually compacted hair, not true horn.
Ceratopsidae: The "horns" of the Triceratops were extensions of its skull bones although debate exists over whether they had a keratin covering.
Monodontidae: Narwhals have a single long tusk, a modified tooth, which looks like a horn, and is spiralled like that of the fictional unicorn.

Many animal species in various families have tusks, which often serve the same functions as true horns, but are in fact oversize teeth. These include the Moschidae (Musk deer, which are ruminants), Suidae (Wild Boars), Proboscidea (Elephants), Monodontidae (Narwhals) and Odobenidae (Walruses).

[edit] Animal uses of horns

Wildlife have a variety of uses for horns and antlers, including fighting members of their own species for territory, dominance and mating priority. In addition, horns may be used to root in the soil or strip bark from trees. In animal courtship there are specific species that use horns in displays of attraction. For example, the male Blue Wildebeest reams the bark and branches of trees to impress the female and lure her into his territory. Horns are also used by some animals with true horns to provide cooling. Since horns are an extension of the skin, they have blood vessels in them, allowing the horns to function as a radiator to cool the blood.

[edit] Human uses of horns

Use of animal horns is controversial, especially if the animal was specifically hunted for the horn as a trophy or object of decoration or utility. Some animals are threatened or endangered to reduced populations partially from pressures of such hunting.

Some peoples use bovid horns as musical instruments, for example the shofar. These have evolved into brass instruments 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 made of metal.

Drinking horns are bovid horns cleaned and polished and used as drinking vessels. (See also the legend of the Horn of plenty, or Cornucopia).

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.

Horn can also refer to keratin, the material of which a horn is made. This is most common when a horn is used as a material in tools, furniture, decoration, and other uses. In these applications, horn is valued for its hardness, and has given rise to the expression hard as horn.

Horns are sometimes made of ivory. "Horn" buttons are usually made from deer antlers, not true horn.