与其他 phocids 物种（如灰海豹）相比，港海豹体型较小。众所周知，灰海豹在整个哺乳期都禁食。
Harbor seals are small compared with other phocids species such as grey seals, all of which are known to fast for the entire lactation period.
它们的身体呈流线型，后肢完全消失，身体上长出了尾片和喷水孔，所有这些特征都无法掩饰它们与陆生哺乳动物之间的亲缘关系。
Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole cannot disguise their affinities with land dwelling mammals.
几乎所有哺乳动物身体外表都长了毛皮或毛发。
应用推荐