Sea otter's (Enhydra lutris) are an aquatic mammal and is one of the thirteen species of otter. They are native to the Pacific Ocean ranging from Japan to California, but with many gaps in their population. Sea otters are classified as a keystone species because they benefit the ecosystem and other species around them. Unfortunately, they are listed as endangered because they face many threats, such as hunting, trapping, fishing, climate change, pollution, and oil spills.