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Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The extant members of this group are: dromedary camel, Bactrian camels, wild or feral camels, llamas, alpacas, vicuñas, and guanacos. Camelids are even-toed ungulates classified in the order Cetartiodactyla, along with pigs, hippopotami, whales, deer, giraffes, cattle, goats, antelope, and many others. ==Characteristics== Camelids are large, strictly herbivorous animals with slender necks and long legs. They differ from ruminants in a number of ways.〔Fowler, M.E. (2010). "Medicine and Surgery of Camelids", Ames, Iowa: Wiley-Blackwell. Chapter 1 General Biology and Evolution addresses the fact that camelids (including camels and llamas) are not ruminants, pseudo-ruminants, or modified ruminants.〕 Their dentition show traces of vestigial central incisors in the upper jaw, and the third incisors have developed into canine-like tusks. Camelids also have true canine teeth and tusk-like premolars, which are separated from the molars by a gap. The musculature of the hind limbs differs from those of other ungulates in that the legs are attached to the body only at the top of the thigh, rather than attached by skin and muscle from the knee upwards. Because of this, camelids have to lie down by resting on their knees with their legs tucked underneath their bodies. They have three-chambered stomachs, rather than four-chambered ones; their upper lips are split in two, with each part separately mobile; and, uniquely among mammals, their red blood cells are elliptical.〔 They also have a unique type of antibodies which lack the light chain, in addition to the normal antibodies found in other mammals. These so-called heavy-chain antibodies are being used to develop single-domain antibodies with potential pharmaceutical applications. Camelids do not have hooves, rather they have two-toed feet with toenails and soft foot pads (Tylopoda is Greek for "padded foot"). Most of the weight of the animal rests on these tough, leathery sole pads. The South American camelids, adapted to steep and rocky terrain, can move the pads on their toes to maintain grip. Many fossil camelids were unguligrade and probably hooved, in contrast to all living species. Camelids are behaviorally similar in many ways, perhaps most notably in their walking gait during which both legs on the same side are moved simultaneously. The consequent swaying motion of camelids large enough for human beings to ride is legendary. Dromedary camels, bactrian camels, llamas and alpacas are all induced ovulators. The three Afro-Asian camel species have developed extensive adaptations to their lives in harsh, near-waterless environments. Wild populations of the Bactrian camel are even able to drink brackish water, and some herds live in nuclear test areas.〔(Wild Bactrian Camels Critically Endangered, Group Says ) National Geographic, 3 December 2002〕 Comparative table of the eight mammals in the family Camelidae (ordered by weight): 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「camelid」の詳細全文を読む スポンサード リンク
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