As members of the weasel or mustelid family, southern sea otters are the
smallest marine mammal. Like other members of this family, they have very
thick fur. In fact, at 850,000 to 1 million hairs per square inch, sea
otters have the thickest fur of any mammal. Sea otters are keystone
species, they control the sea urchin populations, that would otherwise
inflict damage on kelp forests off our coast.
🦦More on Wikipedia