sea otter

With its furry coat, friendly face, and playful nature, the sea otter is perhaps one of the most endearing animals in the sea. But these marine mammals are more than cute; they're fascinating creatures with unusual behaviors and great intelligence. Unfortunately, this graceful swimmer was once most valued for its thick fur and was almost hunted to extinction.

Scientific name: Enhydra lutris
Size: males grow to be 4.5 feet long
Weight: males weigh as much as 80 pounds (females are smaller)
Habitat: along rocky shorelines of the northern Pacific
Diet: sea urchins, crabs, clams, and fish
Status: threatened due to habitat loss
Cool fact: has the thickest fur of any animal on Earth

Image credits: courtesy of NPS, Olympic National Park.