Sea otters are not only adorable but play an incredibly vital role in maintaining the ecosystems they inhabit. Sea otters regulate their habitats by feeding on sea urchins, which is why they are classified as a keystone species. They also eat crabs, clams, and mussels. Adult male sea otters typically weigh anywhere from 49 to 99 pounds. Their lifespan is 23 years, but can be cut short by great white sharks. Unfortunately, these little guys do not stand a chance against larger animals due to them being the smallest mammals in the sea. They can only reach up to about 5 feet in length. While they are not great fighters, they are extremely gifted when it comes to their aquatic adaptations. They are incredibly buoyant, allowing them to easily float on the water like a pool float. Not only that, but they are capable swimmers who can hold their breath for over five minutes. Regretfully, these crucial yet goofy animals are endangered, partially due to humans. Oil spills within the ocean are killing them off. Hopefully, these fascinating creatures will make a comeback soon.