• A hedgehog has up to 16,000 spines. Males “rattle” these in their mating “dance.” Adult hedgehogs sometimes lick or “anoint” their spines with frothy saliva. Scientists still don’t know why.
• The naked mole rat is nearly hairless and live in underground colonies. These African rodents warm themselves in tunnels that lie close to the surface and are heated by the sun.
• An amazing array of mammalian body-parts are made from keratin, a protein found in the skin. These include hair, quills, scales, spines, horns, hooves, claws, whale baleen, and the fingernails and toenails of primates, including humans.

Discovered in 1907 on an expedition in the Alaskan Arctic, this preserved mammoth hair is about 10,000 years old. © AMNH/D. Finnin

Skin, Hair & Armor

What’s 11 feet tall, 10,000 years old and wears a skirt?

The woolly mammoth…obviously!

During the dawn of the 20th century, explorers discovered 10,000 year-old mammoth hair in the Alaskan Arctic. These huge mammals developed thick layers of hair to protect their skin from frigid weather. Among the layers were 3-foot-long (90 centimeters) strands of hair covering the flanks and belly in a “skirt,” like those on musk oxen living today.

The woolly mammoth’s coat seems like a fairly mild adaptation when compared to the Chinese pangolin, an endangered mammal living in the forests and grasslands of Central and Southeast Asia. When frightened, pangolins roll into a ball and, using strong muscles in their skin, raise their scales into a series of sharp blades. Their line of defense doesn’t stop there –pangolins can target attackers with jets of foul-smelling liquid.

In fact, the evolution of mammalian skin has taken some pretty extreme turns – from the flexible, bony shells of the armadillo to the pangolin’s scales to barbed quills of the porcupine.