flipper

Not only that, but when a wave threatened to return the seal to danger, the humpback used its massive flipper (at five metres, the longest in the animal kingdom) to nudge it back on.

不仅如此，当一个浪头即将把海豹扫回险境之时，座头鲸还利用它的巨大的鳍状肢（五米长，动物王国中最长的）把它轻轻地推了回来。