A mammal of the Delphinidae family in the suborder Toothed Cetacea. A small dolphin with a large round head that lives in coastal and river areas from the Bay of Bengal to northern Australia, Indonesia, and the Indochina Peninsula. It is found 500 to 1,000 km upstream from the mouth of the Irrawaddy, Mekong, and Mahakam rivers, and is said to end its life there. Body length is 2 to 2.2 meters. Its back is blue-black, its sides are pale, and its belly is white. Its dorsal fin is small and low, but its pectoral fins are large. It has 12 to 17 teeth on each side. Its seven cervical vertebrae are all detached, which is a primitive feature. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
歯クジラ亜目マイルカ科の哺乳類。ベンガル湾から北オーストラリア,インドネシア,インドシナ半島などの沿岸や河川に生息する丸い大きな頭をもつ小型イルカ。イラワジ川やメコン川,マハカム川などでは河口から500~1000km上流にまで分布し,その場所で一生を終えるらしい。体長2~2.2m。背面青黒色で,体側は淡く,腹面は白い。背びれは小さく低いが,胸びれは大きい。歯は上下左右それぞれ12~17本ある。7個の頸椎が全部遊離している点は原始的な特徴である。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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