Sea otters are marine mammals found along the coasts of the northern Pacific Ocean. They have thick fur, which keeps them warm in cold waters, and they can weigh between 50 to 100 pounds. Sea otters are known for their playful behavior and often use tools, such as rocks, to crack open shellfish. These animals play a crucial role in their ecosystem by helping to maintain kelp forest health. By preying on sea urchins, they prevent these herbivores from overgrazing on kelp, which can lead to the decline of these underwater forests.