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The Steller's sea cow (''Hydrodamalis gigas'') is an extinct herbivorous marine mammal. It was the largest member of the order Sirenia, which includes its closest living relative, the dugong (''Dugong dugon''), and the manatees (''Trichechus'' spp.). It reached up to in length, making it among the largest mammals other than whales to have existed in the holocene epoch. Although the sea cow had formerly been abundant throughout the North Pacific, by 1741, when it was first described by Georg Wilhelm Steller, chief naturalist on an expedition led by explorer Vitus Bering,〔; (【引用サイトリンク】url=http://www.sirenian.org/stellers.html )〕 its range had been limited to a single, isolated population surrounding the uninhabited Commander Islands. Within 27 years of discovery by Europeans, the slow-moving and easily captured Steller's sea cow was hunted to extinction. ==Description== The sea cow grew to at least in length as an adult, much larger than the manatee or dugong; however, concerning their weight, Steller's work contains two contradictory estimates: 4 and 24.3 metric tons. The true value is estimated to lie between these figures, at around 8 to 10 t. It looked somewhat like a large seal, but had two stout forelimbs and a whale-like fluke. According to Steller, it "is not the sea cow of Aristotle, for it never comes upon dry land to feed", but it can use its fore limbs for a number of tasks: swimming, walking on the shallows of the shore, supporting himself on the rocks, digging for algae and seagrasses, fighting, and embracing each other.〔 ((PDF ))〕 "It is covered with a thick hide, more like unto the bark of an ancient oak than unto the skin of an animal; the manatee’s hide is black, mangy, wrinkled, rough, hard, and tough; it is void of hairs, and almost impervious to an ax or to the point of a hook."〔 Its head is small and short compared to the huge body. The upper lip is so large, so broad, and extends so far beyond the mandible, that the mouth appears to be located underneath the skull. The mouth is rather small, toothless, and equipped with double lips, both above and below. When it closes its mouth, the space between the lips is filled up with a dense array of very thick white bristles, long. These bristles take the place of teeth and are used to pull out seaweed and hold food. Mastication is performed by two white bones or solid tooth masses.〔 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「Steller's sea cow」の詳細全文を読む スポンサード リンク
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