Large baleen whales primarily use the lower frequencies and are often limited in their repertoire 大长须鲸最初使用低频，他们的全套本领很有限。
3.
However , the position of the eyes so restricts the field of vision in baleen whales that they probably do not have stereoscopic vision 但是，由于眼睛的位置太受约束，长须鲸可能没有立体视觉。
4.
They have also unearthed some clues from the ensuing oligocene , when the modern suborders of cetaceans ? the mysticetes ( baleen whales ) and the odontocetes ( toothed whales ) ? arose 在随后的渐新世地层中，他们也找到了一些线索；须鲸亚目（有鲸须的鲸鱼）与齿鲸亚目（有齿的鲸鱼）就是在那时候分化的。
5.
Toothed species in general employ more of the frequency spectrum , and produce a wider variety of sounds , than baleen species ( though the sperm whale apparently produces a monotonous series of high - energy clicks and little else ) 齿鲸一般是用更多频率并且产生一个广的变化的声音，和长须鲸相比(尽管抹香鲸显然能发出一系列单调的高能咔嚓声，其他基本不会) 。
