A horn is a pointed projection of the skin The skin is a soft outer covering of an animal, in particular a vertebrate. Other animal coverings such the arthropod exoskeleton or the seashell have different developmental origin, structure and chemical composition. The adjective cutaneous literally means "of the skin" . In mammals, the skin is the largest organ of the integumentary on the head of various animals, consisting of a covering of horn (keratin Keratin refers to a family of fibrous structural proteins. Keratin is an intermediate filament; when assembled in bundles, it is tough and insoluble forming hard, unmineralized structures found in reptiles, birds, amphibians, and mammals. They are rivalled as biological matter in toughness only by chitin and other proteins Proteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded) surrounding a core of living bone Bones are rigid organs that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue. Because bones come in a variety of shapes and have a complex internal and external structure. True horns are found mainly among the ruminant Physiologically, a ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first stomach, known as the rumen, then regurgitating the semi-digested mass, now known as cud, and chewing it again. The process of rechewing the cud to further break down plant matter and stimulate artiodactyls The even-toed ungulates form the mammal order Artiodactyla, the group that contains the pigs, peccaries, hippopotamuses, camels, chevrotains , deer, giraffes, pronghorn, antelopes, sheep, goats, and cattle. They are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in odd-,[citation needed] in the families Antilocapridae Antilocapridae is a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids. Only one species, the pronghorn , is living today; all other members of the family are extinct. The living pronghorn is a small ruminant mammal resembling an antelope. It bears small, forked horns (pronghorn The Pronghorn , is a species of artiodactyl mammal native to interior western and central North America. Though not a true antelope, it is often known colloquially in North America as the Prong Buck, Pronghorn Antelope or simply Antelope, as it closely resembles the true antelopes of the Old World and fills a similar ecological niche due to) and Bovidae A bovid is any of almost 140 species of cloven-hoofed mammals belonging to the family Bovidae. The family is widespread, being native to all continents except South America, Australia and Antarctica, and diverse: members include bison, African Buffalo, water buffalo, antelopes, gazelles, sheep, goats, muskox, and domestic cattle (cattle Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius. Cattle are raised as livestock for meat (beef and veal), as dairy animals for milk and other dairy products,, goats The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep: both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of goat, antelope Antelope is a term referring to many even-toed ungulate species found in the family Bovidae. The term refers to a ‘miscellaneous’ group within the family encompassing the species which are not cattle, sheep, buffalo, bison, or goats. A group of antelope is called a herd etc.). One pair of horns is usual, but two pairs occur in a few wild species and in a few domesticated Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. A defining characteristic of domestication is artificial selection by humans. Some species such as the Asian Elephant, numerous members of which have for many centuries been used as breeds of sheep This is a list of domestic sheep breeds. Domestic sheep are partially derived from mouflon (Ovis orientalis) stock, and have diverged sufficiently to be considered a different species. Partial or deformed horns in livestock are often called scurs.
Horns usually have a curved or spiral In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point shape, often with ridges or fluting. In many species only the males have horns. Horns start to grow soon after birth, and continue to grow throughout the life of the animal (except in pronghorns Antilocapridae is a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids. Only one species, the pronghorn , is living today; all other members of the family are extinct. The living pronghorn is a small ruminant mammal resembling an antelope. It bears small, forked horns, which shed the outer layer annually, but retain the bony core). Similar growths on other parts of the body are not usually called horns, but spurs, claws A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end of the leg or tarsus for gripping a or hoofs Most even-toed ungulates have two main hooves on each foot, together called a cloven hoof. Most of these cloven-hoofed animals also have two smaller hoofs called dew-claws a little further up the leg – these are not normally used for walking, but in some species with larger dew-claws (such as deer and pigs) they may touch the ground when running.
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