Fancy Hair

Hair is a structure that is unique to mammals, growing from small organs called follicles found just under the outer layer of skin.  Hair can be modified into different forms providing insulation, camouflage, signaling, sensing movement, and for use in defense. 

The hair shaft extends above the surface of the skin.  It is formed from layers of a protein called keratin.  When bundled together, the layers form strong and hardened strands.  There are more than 50 types of keratin that together form hair, nails, outer skin layers, claws, hooves, horns, plates, and baleen.  Many keratin proteins are combined with varying amounts of an amino acid called cysteine, that provides additional strength and hardness.  Let’s investigate some forms of hair that help keep mammals protected.

Left: Armadillo scutes encapsulating their body by DonArnold, 2025; upper right: Armadillo showing arrangement of scutes and plates covering their body by DonArnold, 2025; lower right: Southern three-banded Armadillo, rolled into a ball, by MiraianeDL, Getty Images

An armadillo has a tough shell encasing the sides and upper parts of its body.  The shell is composed of solid pieces covering hips and shoulders and bony plates in between.  The entire shell is covered with scutes, small scale-like structures made from hair flattened into a tough, leathery layer protecting the outside of the shell.  The bands form a flexible pattern that allow the animal to move quickly with very few of the softer body parts exposed.  The three-banded armadillo of South America can roll up into an almost impenetrable ball with only the scutes exposed.

The pangolin looks similar to an armadillo, and although they are not related, they do possess similar features.  Pangolins can also roll up into a tight ball.  Their tail, covered with sharp-edged scutes can be left outside the ball and used to lash out against potential predators.  However, being smaller animals, this form of defense provides almost no protection against their greatest threat – humans.  They are the most trafficked mammal in the world, hunted for their meat which is served as a delicacy in many parts of the world.  Their scutes are also in high demand by cultures for medicine and by leather goods industries.

Mammalian spines and quills are two other structures formed from hair.  Quills have a hardened outer covering, and a soft, spongy core, and are found in porcupines, echidnas, and some rodents.  Spines also have a hard outer covering of keratin, but consist of solid layers of hair inside.  Both structures are generally straight and rigid, and may be sharply pointed, with or without a barb at the end. 

Porcupines have quills with sharp tips and a backward facing barb near their ends.  Porcupines cannot shoot a quill at an attacker, but if the attacker comes into contact with any of the quills, their sharp ends easily penetrate skin.  Quills are brittle and often break off after being embedded, and the barb makes them difficult to remove, resulting in a painful experience for an aggressor that gets too close. 

Hedgehogs are known for their spines, which are all the same length, not barbed, and do not come out easily.  They are more like prickles, providing a pointed reminder to an aggressor not to get too close.  A hedgehog can roll into a ball with all of the spines projecting outwards, making it very difficult to grab or bite the animal without being pricked any number of times.

At the Jurica-Suchy Nature Museum, you can learn about these defense tactics, as well as those of other species and how they provide for their own safety.  Make a reservation to come see us by visiting our website at:  https://ben.edu/campus-links/jurica-suchy-nature-museum/  (click on Register to Visit the Museum)