Deer
Deer (singular and plural) are the ruminant mammals forming the family Cervidae. The two main groups are the Cervinae, including the muntjac, the elk (wapiti), the fallow deer and the chital, and the Capreolinae, including the reindeer (caribou), the roe deer and the moose. Female reindeer, and male deer of all species except the Chinese water deer, grow and shed new antlers each year. In this they differ from permanently horned antelope, which are part of a different family (Bovidae) within the same order of even-toed ungulates (Artiodactyla).
The musk deer of Asia and water chevrotain (or mouse deer) of tropical African and Asian forests are not usually regarded as true deer and form their own families: Moschidae and Tragulidae, respectively.
Deer appear in art from Paleolithic cave paintings onwards, and they have played a role in mythology, religion, and literature throughout history, as well as in heraldry. Their economic importance includes the use of their meat as venison, their skins as soft, strong buckskin, and their antlers as handles for knives. Deer hunting has been a popular activity since at least the Middle Ages, and remains an important business today.
Distribution
Deer constitute the second most diverse family after bovids. Though of a similar build, deer are strongly distinguished from antelopes by their antlers, which are temporary and regularly regrown unlike the permanent horns of bovids. Characteristics typical of deer include long, powerful legs, a diminutive tail and long ears. Deer exhibit a broad variation in physical proportions. The largest extant deer is the moose, which is nearly 2.6 metres (8.5 ft) tall and weighs up to 800 kilograms (1,800 lb). The elk stands 1.4–2 metres (4.6–6.6 ft) at the shoulder and weighs 240–450 kilograms (530–990 lb). On the contrary, the northern pudu is the smallest deer in the world; it reaches merely 32–35 centimetres (13–14 in) at the shoulder and weighs 3.3–6 kilograms (7.3–13.2 lb). The southern pudu is only slightly taller and heavier. Sexual dimorphism is quite pronounced – in most species males tend to be larger than females, and, except for the reindeer, only males possess antlers.
Coat colour generally varies between red and brown, though it can be as dark as chocolate brown in the tufted deer or have a grayish tinge as in elk. Different species of brocket deer vary from gray to reddish brown in coat colour. Several species such as the chital, the fallow deer and the sika deer feature white spots on a brown coat. Coat of reindeer shows notable geographical variation. Deer undergo two moults in a year; for instance, in red deer the red, thin-haired summer coat is gradually replaced by the dense, greyish brown winter coat in autumn, which in turn gives way to the summer coat in the following spring. Moulting is affected by the photoperiod.
Deer are also excellent jumpers and swimmers. Deer are ruminants, or cud-chewers, and have a four-chambered stomach. Some deer, such as those on the island of Rùm, do consume meat when it is available.
Nearly all deer have a facial gland in front of each eye. The gland contains a strongly scented pheromone, used to mark its home range. Bucks of a wide range of species open these glands wide when angry or excited. All deer have a liver without a gallbladder. Deer also have a tapetum lucidum, which gives them sufficiently good night vision.
Antlers
All male deer possess antlers, with the exception of the Chinese water deer, in which males have long tusk-like canines that reach below the lower jaw. Females generally lack antlers, though female reindeer bear antlers smaller and less branched than those of the males. Occasionally females in other species may develop antlers, especially in telemetacarpal deer such as European roe deer, red deer, white-tailed deer and mule deer and less often in plesiometacarpal deer. A study of antlered female white-tailed deer noted that antlers tend to be small and malformed, and are shed frequently around the time of parturition.
The fallow deer and the various subspecies of the reindeer have the largest as well as the heaviest antlers, both in absolute terms as well as in proportion to body mass (an average of 8 grams (0.28 oz) per kilogram of body mass); the tufted deer, on the other hand, has the smallest antlers of all deer, while the pudú has the lightest antlers with respect to body mass (0.6 grams (0.021 oz) per kilogram of body mass). The structure of antlers show considerable variation; while fallow deer and elk antlers are palmate (with a broad central portion), white-tailed deer antlers include a series of tines sprouting upward from a forward-curving main beam, and those of the pudú are mere spikes. Antler development begins from the pedicel, a bony structure that appears on the top of the skull by the time the animal is a year old. The pedicel gives rise to a spiky antler the following year, that is replaced by a branched antler in the third year. This process of losing a set of antlers to develop a larger and more branched set continues for the rest of the life. The antlers emerge as soft tissues (known as velvet antlers) and progressively harden into bony structures (known as hard antlers), following mineralisation and blockage of blood vessels in the tissue, from the tip to the base.
Antlers might be one of the most exaggerated male secondary sexual characteristics, and are intended primarily for reproductive success through sexual selection and for combat. The tines (forks) on the antlers create grooves that allow another male's antlers to lock into place. This allows the males to wrestle without risking injury to the face. Antlers are correlated to an individual's position in the social hierarchy and its behaviour. For instance, the heavier the antlers, the higher the individual's status in the social hierarchy, and the greater is the delay in shedding the antlers; males with larger antlers tend to be more aggressive and dominant over others. Antlers can be an honest signal of genetic quality; males with larger antlers relative to body size tend to have increased resistance to pathogens and higher reproductive capacity.
https://en.wikipedia.org/wiki/Deer
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