sea cow

sea-cow的词性：
n.（名词）

1. Any of several large, cylindrical, herbivorous marine mammals of the order Sirenia, having a paddlelike tail and rounded front flippers, including the manatee, dugong, and the very large species Hydrodamalis stelleri of the northern Pacific that became extinct in the late 1700's. Also called sirenian
海牛：任一种大型的、圆柱体的海牛目食草海生哺乳动物，长有桨状的尾巴，圆形前鳍，包括海牛、儒艮及北太平洋的大型世儒艮 科动物，已于18世纪晚期绝迹 也作 sirenian