Only the order Monotremata shares this trait; they are only mammals that do not have nipples. The only surviving examples of these mammals along with the duck-billed platypus are four species of echidnas known as spiny anteaters, which live in Australia and New Guinea. These five species are also the only egg-laying mammals. To find food, platypuses use the electro-receptor system on their bills. This bizarre mammal doesn't have a stomach or teeth. Sources: Department of Primary Industries and Water, Tasmania Online, UC Berkley
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Curiosity StaffDecember 22, 2014
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