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9 nearly hairless mammals

dolphin, cetaceans, hairless mammals

Photo: Willyam Bradberry/Shutterstock

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Cetaceans

Cetaceans — or the whales, dolphins and porpoises — are the largest group of hairless mammals, and for good reason: Hair doesn't make a lot of sense given their aquatic lifestyles. They have opted instead to insulate themselves with a thick layer of blubber.

Although all cetaceans exhibit hair on their heads as fetuses, hair is eventually lost except for in a few species, such as with the bowhead whale, which has hairs on its lips, chin, snout and behind its blowhole.