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9 nearly hairless mammals

By: Bryan Nelson on Nov. 18, 2013, 9 a.m.
A hippo parent and its calf

Photo: Volodymyr Burdiak/Shutterstock

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Hippos lack hair for much the same reason that other aquatic and semi-aquatic mammals do — fat is a more useful insulator for large animals that spend most of their time in the water.

Interestingly, despite looking like they might be related to pigs and other terrestrial even-toed ungulates, hippos are actually most closely related to modern-day cetaceans. So hairlessness seems to run in the family!