Platypus

The platypus (Ornithorhynchus anatinus) is one of the most extraordinary animals on Earth — so bizarre that when European scientists first encountered its preserved skin in 1799, they thought it was a taxidermist's hoax. The platypus is one of only five surviving monotremes (egg-laying mammals). It combines features that seem to belong to completely different animals: a duck bill, beaver tail, otter feet, and it lays eggs. Males have venomous spurs on their hind legs capable of causing excruciating pain in humans. Perhaps most remarkably, the platypus uses electroreception to hunt — specialized receptors in its bill detect the electrical fields generated by the muscles of prey underwater, allowing it to hunt with its eyes, ears, and nose closed. This makes it the only mammal to use this sense in the same way electric fish do. The platypus genome is itself extraordinary — it contains chicken genes, reptile genes, and mammal genes, reflecting its ancient evolutionary lineage.