Whales and dolphins have been found with hind limbs; this rare occurrence is due to the reemergence of a trait they inherited from their terrestrial ancestors.

发现鲸和海豚身上有后肢；这种稀有的现象是由于它们在陆地上的祖先身上的特征再次被遗传。

youdao

30 species of whales, dolphins and porpoises.

30种鲸，海豚和鼠海豚。

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More than 300 thousand small whales, dolphins and porpoises die due to commercial fishing each year.

每年超过300,000只幼年鲸鱼、海豚和鼠海豚由于商业捕捞而死亡。

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"They asked me to come with them into this cove in Taiji,Japan where they massacre dolphins and small whales.

VOA: standard.2010.08.04

I paddled a surfboard into this inlet that was pink red with blood from these large dolphins, these pilot whales that were being piked.

VOA: standard.2010.08.04

Well-known marine animals, such as whales or dolphins represent a tiny fraction of marine biodiversity.

UNESCO: THEMES

If we can make homes for whales and dolphins, the ocean may just have a chance.

BBC: Saving the seas for marine mammals

Whales and dolphins have complex cultures, too, which vary from group to group within a species.

ECONOMIST: A declaration of the rights of cetaceans