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 males, with the exception of reindeer/caribou. Antlers are shed and regrown each year and function primarily as objects of sexual attraction and as weapons. Antler comes from the Old French antoillier (see present French : "Andouiller", from ant-, meaning before, oeil, meaning eye and -ier, a suffix indicating an action or state of being) possibly from some form of an unattested Latin word *anteocularis, "before the eye" (and applied to the word for "branch" or "horn"). Antlers are unique to cervids. The ancestors of deer had tusks (long upper canine teeth). In most species, antlers appear to replace tusks. However, one modern species (the water deer) has tusks and no antlers and the muntjacs have small antlers and tusks. The musk deer, which are not true cervids, also bear tusks in place of antlers. In contrast to antlers, horns—found on pronghorns and bovids, such as sheep, goats, bison and cattle—are two-part structures that usually do not shed. A horn's interior of bone is covered by an exterior sheath made of keratin (the same material as human fingernails and toenails). Antlers are usually found only on males. Only reindeer (known as caribou in North America) have antlers on the females, and these are normally smaller than those of the males. Nevertheless, fertile does from other species of deer have the capacity to produce antlers on occasion, usually due to increased testosterone levels. The "horns" of a pronghorn (which is not a cervid but a giraffoid) meet some of the criteria of antlers, but are not considered true antlers because they contain keratin. Each antler grows from an attachment point on the skull called a pedicle. While an antler is growing, it is covered with highly vascular skin called velvet, which supplies oxygen and nutrients to the growing bone.