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Hyraxes (from the Greek , ''hurax'', "shrewmouse"), also called dassies,〔"Hyracoidea" in ''Grzimek's Animal Life Encyclopedia, Vol. 15: Mammals. Gale Publishing.'' Online version accessed April 2014.〕 are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are often mistaken for rodents, but are more closely related to elephants and manatees. Four species are recognised; the rock hyrax (''Procavia capensis''), the yellow-spotted rock hyrax (''Heterohyrax brucei''), the western tree hyrax (''Dendrohyrax dorsalis'') and the southern tree hyrax (''Dendrohyrax arboreus''). Their distribution is limited to Africa and the Middle East. ==Characteristics== Hyraxes retain a number of primitive mammalian characteristics; in particular, they have poorly developed internal temperature regulation, which they compensate for by behavioural thermoregulation, such as huddling together and basking in the sun. Unlike most other browsing and grazing animals, they do not use the incisors at the front of the jaw for slicing off leaves and grass, rather, they use the molar teeth at the side of the jaw. The incisors are nonetheless large, and grow continuously through life, similar to rodents. There is a small diastema between the incisors and the cheek teeth. The dental formula for hyraxes is . Although not ruminants, hyraxes have complex, multi-chambered stomachs that allow symbiotic bacteria to break down tough plant materials; their overall ability to digest fibre is similar to that of the ungulates.〔von Engelhardt et al. (1978) Production of methane in two non-ruminant herbivores. Comparative Biochemistry and Physiology Part A: Physiology 60 (3) 309-311〕 Their mandibular motions (see video) are deceptively similar to chewing cud, but the hyrax is physically incapable of regurgitation〔http://www.ncbi.nlm.nih.gov/pubmed/8529006 The gastrointestinal tract of the rock hyrax (Procavia habessinica). 1. Morphology and motility patterns of the tract. Björnhag G1, Becker G, Buchholz C, von Engelhardt W.〕〔JB Sale - JE Afr. Nat. Hist. Soc, 1966〕 as in the even-toed ungulates and the merycism of some of the macropods. This behaviour is referred to in a passage in the Bible ((Leviticus 11:5 )) which erroneously describes hyraxes as chewing the cud. Some authors believe these chewing motions are a form of agonistic behaviour when the animal feels threatened.〔http://www.zootorah.com/hyrax/hyrax.pdf〕 Hyraxes inhabit rocky terrain across sub-Saharan Africa and the Middle East. Their feet have rubbery pads with numerous sweat glands, which help the animal maintain its grip when quickly moving up steep, rocky surfaces. Hyraxes have stumpy toes with hoof-like nails; there are four toes on each front foot and three on each back foot.〔http://www.awf.org/wildlife-conservation/hyrax〕 They also have efficient kidneys, retaining water so that they can better survive in arid environments. Female hyraxes give birth to up to four young after a gestation period of between seven and eight months, depending on the species. The young are weaned at one to five months of age, and reach sexual maturity at 16 to 17 months. Hyraxes live in small family groups, dominated by a single male who aggressively defends the territory from rivals. Where there is abundant living space, the male may dominate multiple groups of females, each with their own range. The remaining males live solitary lives, often on the periphery of areas controlled by larger males, and mate only with younger females. Hyraxes have highly charged myoglobin, which has been inferred to reflect an aquatic ancestry. 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「Hyrax」の詳細全文を読む スポンサード リンク
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