Marine mammals:
* Seals: Their fur has a dense undercoat that traps air and a thick outer layer of guard hairs that shed water.
* Sea otters: They have the densest fur of any mammal, with an estimated 1 million hairs per square inch. This fur traps a layer of air, providing insulation and buoyancy.
* Whales: While whales are not furry, they do have a layer of blubber beneath their skin that acts as insulation and keeps them warm in cold water.
Terrestrial mammals:
* Beavers: Their fur has a double layer, with a dense undercoat and a coarser outer coat. This helps them stay warm and dry in their aquatic environment.
* Water shrews: These small mammals have a water-repellent fur that helps them swim and forage for food in water.
* Otters: Similar to sea otters, river otters have dense fur that traps air and keeps them warm and buoyant in water.
* Polar bears: Their fur is hollow and acts as insulation, keeping them warm in frigid Arctic waters.
Other mammals with water-repellent fur:
* Dogs: Many dog breeds have a water-repellent coat, particularly those with double coats.
* Cats: Similar to dogs, some cats have a water-repellent coat, especially those with a dense undercoat.
It's important to note that while these mammals have fur that is water-repellent, it's not completely waterproof. Over time, water can penetrate their fur and cause them to become wet.