Sea otters are native to the northern and eastern coasts of the North Pacific Ocean. The otter featured in today"s image was photographed in Prince William Sound, Alaska, United States. Weighing 14-45 kilograms, they"re expert foragers, diving to the seabed to find food. These clever critters are smart as well as cute: they use rocks to crack open shellfish, making them one of the few animals that use tools. There used to be as many as 300,000 in the wild, but they were heavily hunted for almost two centuries, as their dense fur was highly prized. By 1911, it is thought that only around 2,000 were left. Thankfully, an international hunting ban, conservation efforts and reintroduction programs have helped them rebound, and they are now found in about two-thirds of their historic habitat. Despite this success, some populations are still struggling, and sea otters are still an endangered species.