One of the most expensive types of animal fur comes from the slowest swimming marine mammal. What animal is this?

The incredibly dense and luxurious pelt of the sea otter makes it one of the most valuable in the world. With up to one million hairs per square inch, it is the thickest fur of any animal on Earth. Unlike other marine mammals such as whales or seals, sea otters lack a thick layer of blubber for insulation against the cold. Instead, their remarkable double-layered fur traps a layer of air right against their skin, which keeps them warm and buoyant in the frigid waters of the North Pacific.

This amazing coat was also nearly its downfall. During the great (Review) maritime fur trade of the 18th and 19th centuries, hunters pursued them relentlessly, driving the species to the brink of extinction. Their status as the slowest swimming marine mammal, with a top speed of only about 5.6 miles per hour, unfortunately made them a more vulnerable target compared to faster marine life.

Thankfully, international protection efforts in the 20th century have allowed sea otter populations to rebound in many of their former habitats. Today, they are recognized as a keystone species, playing a crucial role in maintaining the health of coastal kelp forest ecosystems.