Here's why:
* Aquatic Adaptations: They have webbed feet, a flattened tail for swimming, and a dense, waterproof fur coat. They spend a significant portion of their time foraging for food in water.
* Terrestrial Adaptations: They also have strong legs for walking and digging burrows on land. They use their burrows for nesting and raising young.
So, while they are primarily known for their aquatic life, they also have the adaptations and behavior necessary for living on land.