The sea otter lives along the Pacific Coast of North America. Sea otters have about 26,000-165,000 hairs per square centimeter of skin. This helps them regulate body temperature, which is why much of their day is spent keeping their fur clean. Unlike most marine mammals, the sea otter does not have a layer of insulating blubber. Instead, they rely on a layer of air trapped in their fur, which they keep topped off by blowing into the fur with their mouths. Their thick fur is also why they were nearly hunted to extinction. Their thick luxurious coats were prized in the fur trade. They often keep a large stone in a pouch under their forearm for smashing open shellfish, making them one of the few animals which use tools. A full grown male can weigh up to 66lbs. Unlike other otters that spend most of their time on land, sea otters spend the majority of their time in the water.