The external auditory meatus is tubular and the ears lack pinnae. The bill of a platypus is soft, flexible, and leathery, unlike a bird's beak. Nostrils are located at its tip. While young platypuses have molars, adults are toothless. Young platypuses have teeth, but these are lost in adults.
Food is masticated between horny plates located on each jaw.
Male platypuses have a sharp spur attached to each ankle. A platypus feeds primarily on aquatic crustaceans, insect larvae, and some plants. Duck-billed platypuses live in burrows along the banks of water, including lakes, rivers, and even mountain streams. They have well-developed claws, but these are not as large as the claws of echidnas . Platypuses are excellent diggers.