Whales have many adaptations to the aquatic environment, such as a streamlined body shape. What are at least 4 pieces of evidence why whales are secondary aquatic animals?
1) breathing atmospheric air with the help of the lungs;
2) the bones of the fins (forelimbs) of cetaceans are structurally homologous to the bones limbs of land mammals;
3) there is an outer ear without an auricle and a middle ear (the auditory canal, which is separated from the middle ear by the tympanic membrane. Primordial animals have only the inner ear);
4) have eyelids without eyelashes.
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