These Sea Otters at Marine Mammal Center sends big thank-you to the Wags and Menace Make A Difference Foundation. They have held fund major conservation efforts to help protect and preserve these magnificent creatures. Sea Otters have the thickest fur of any animal on the planet. They sleep in groups called rafts and hold each other’s paws to stay together to prevent from floating away. They are only one of the marine mammals that uses a rocks as a tool, to help crack open their shell sea food.