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灰海豚
,無編輯摘要
灰海豚具远洋习性。通常10头至数十头的群，也有数百头的大群，有时同其它种海豚混群。灰海豚喜欢水深大于180米、水温高于10℃的水域，但有时也到水温为5-6℃的海域中。不集成大群，群体都在数只至20只以下。集群时游速不算太快，但在角斗时游速却很快，瞬时速度估计可达20多海里。在嬉戏的时候，常将半个身体或全身都露出水面以上，溅起高高的浪花，有时还一边用尾鳍击水，一边绕着圈子。
主要在近海和远海的混合区觅食，尤其是600-800米间的水层，也常追随猎物进入沿大陆架的浅水区。它们的食谱包括小型乌贼、鱼类、磷虾、甲壳类动物和头足类动物，最主要的食物是大号的船蛸。<ref>[http://www.iltaw.com/animal/1137 灰海豚Risso's dolphin] </ref>
==生长繁殖==
Infants are dorsally grey to brown and ventrally cream-colored, with a white anchor-shaped area between the pectorals and around the mouth. In older calves, the nonwhite areas darken to nearly black, and then lighten (except for the always dark dorsal fin). Linear scars mostly from social interaction eventually cover the bulk of the body. Older individuals appear mostly white. Most individuals have two to seven pairs of teeth, all in the lower jaw.