Monotremes are mammals that lay eggs. Platypuses are the only living monotreme species, but they are closely related to echidnas, which are also monotremes.
Egg-laying mammals:
Platypuses are one of the few mammals that lay eggs. Other egg-laying mammals include echidnas and marsupials such as the numbat and the Tasmanian devil.
Australian mammals:
Platypuses are native to Australia. They are one of the most iconic Australian animals, along with kangaroos, koalas, and wombats.
Semi-aquatic mammals:
Platypuses are semi-aquatic mammals, which means that they spend part of their time in water and part of their time on land. Other semi-aquatic mammals include seals, sea lions, and otters.
Venomous mammals:
Platypuses are one of the few venomous mammals. The males have a venomous spur on their hind legs that they use to defend themselves against predators. Other venomous mammals include the solenodon and the bumblebee bat.