That said, the water opossum is unusual in lots of ways! For one, it is the world's only living aquatic marsupial. Marsupials aren't afraid of the water and many are fine swimmers, but none spend the majority of their time in the water besides the water opossum. It has a bunch of adaptations to deal with a life in the freshwater streams and ponds in which it's found; it has webbed back feet, its fur repels water and helps keep it buoyant, and its pouch actually seals shut to keep young dry while the mother is swimming. (The male has a waterproof pouch, too, but doesn't keep young in it; its purpose seems to be keeping the male's genitalia dry.) Its creepy, oddly human-like front feet are used to grab food, mostly crustaceans.