Platypuses are semi-aquatic nocturnal mammals from eastern Australia. Unlike most mammals, though, platypuses lay eggs instead of giving birth to live babies. They’ve got dense waterproof fur, wide bills, webbed feet, and a flat tail. Most of the year platypuses live alone in simple burrows and only come together to mate. When a female platypus is ready to lay eggs, she digs a long burrow, extending up to eighty-five feet, just above the waterline of freshwater river, lake, or stream banks. Even though a platypus has nipples, her milk is actually released through pores in her abdomen. (Babies lap milk from where it pools in grooves on her stomach.) Males also have grooves on their stomachs, but they use them to channel venom—used in territorial battles and fights over mates—from a gland to their back feet. Since platypuses keep their eyes, ears, and noses closed while swimming, they rely on their electromagnetic-sensitive bill to find food—worms, insect larvae, crawfish, and freshwater shrimp.