1. Laying Eggs: Unlike most mammals, platypuses lay eggs. This trait is shared with reptiles, birds, and monotremes, the group to which platypuses belong.
2. Venomous Spurs: Male platypuses have venomous spurs on their hind legs, a feature not found in other mammals. This is similar to some reptiles, like vipers.
3. Duck-like Bill: The platypus's bill is broad and flat, resembling a duck's beak. It's used for foraging underwater, a trait more common in birds.
4. Electroreception: Platypuses can detect electrical signals emitted by prey, similar to sharks and some other aquatic animals.
5. Lack of Nipples: Although they nurse their young, platypuses lack nipples and secrete milk through pores on their skin.
6. Primitive Reproductive System: Platypuses have a reproductive system that is more primitive compared to other mammals, lacking a defined uterus and having a cloaca, an opening for waste and reproduction.
7. Lack of Teeth: Adult platypuses lack teeth and use their bill and rough pads on their jaws to grind food.
These unique features make the platypus an intriguing and fascinating mammal that defies easy classification. It represents a living link to the past, showcasing the evolutionary history of mammals.