Platypuses are very strange animals, and on top of the commonly known facts about them, like that they are one the only five mammals in the world that lay eggs,there are many more strange things about them.

Platypuses, on top being one of the only egg-laying mammals, are one of the only venomous mammals. The males have a hollow spur on the back of each hind leg that is connected to a kidney shaped gland that produces the venom. The females have spur buds that stop developing before their first year, and don't have functional glands. The venom is described as being incredibly painful, but not lethal to humans. The spur normally lies flat against the leg, but it is attached to a small bone that allows articulation, meaning it can move the spur perpendicular to the limb, allowing for more attack range than a fixed spur. This trait was apparently not developed uniquely, but is actually a remnant from the platypus' ancestors. Many other ancient groups of mammals have similar spurs, indicating that venomous spurs were once common, and that the platypus is the only remaining example of this trait.

Scientists in 2020 discovered that platypuses glow under UV light. They glow a bright teal color, kind of like Perry the Platypus! When tested, both male anf female specimens glowed uner UV light. Until this discovery, only two species of mammals were known to be bioflurescent, flying squirrels, and opossums. The platypus is now the only monotreme to be bioflurescent. The three mammals are all different types, with the flying squirrels being placental, the opossums being marsupial, and the platpyuses being monotremes, suggesting that this trait is an ancestral trait from an ancestor that all three species share.

Yet another way in which platypuses are incredibly bizzare; they don't have stomachs! Every monotreme, both the platypus and echidna, lost their stomachs during evolution at some point. Scientists looked at 14 different species with and without stomachs to see what was missing. What they found is that every mammal without a stomach lacked the genes for stomach acid. The scientists siggested that the ancestors of these animals likely had diets with no need for stomach acids. It's likely the ancestors of these animals had diets consisting of food that neutralizes the stomach acids, rendering them useless. Because of that, they evolved to lose the stomach entirely because they had no use for it.