Southern sea otter
To stay warm in chilly ocean waters, otters wear the world's densest fur. At its thickest, this two-layer fur is made up of more than a million hairs per square inch. (You've probably got 100,000 hairs or less on your whole head!)
To keep their luxurious coats waterproof, otters
spend many hours a day cleaning and grooming. Such good grooming coats their fur with natural oils from their skin and fluffs it with insulating air bubbles.