One component of the horseshoe crab’s shell is chitin (pronounced ki-tin).  Another is calcium carbonate (more on that later).

Chitin is all around us and is related to keratin which we as humans have in our hair and nails.  Our hair and nails shed and grow and crack thanks to keratin.  And thanks to chitin, the exoskeleton shells of horseshoe crabs molt (break off and regenerate) as they grow from infancy to adulthood.  The exoskeletons also protect the horseshoe crabs in three major ways: defense from being eaten, protection of their inner organs, and protection from dehydration.

Chitin is also related to glucose (sugar).

Exoskeletons are outer shells and we humans have endoskeletons, our bones are inside.

Exoskeletons are present throughout nature.  Think of all the animals you know and how many have exoskeletons.  How many can you think of and how many can you name?  (Some may surprise you.)

The more one learns about chitin, the more fascinating it is.  Besides helping test the cleanliness of medical equipment (see earlier post “Blue Bloods”), chitin is used in surgical thread that decomposes as the wound heals, whipped dessert toppings, it may help to reduce and help cure certain illnesses, it helps clean the water supply, is used as a fertilizer, and is used in paper.  There are many other uses in the medical, food industry, and biotechnology fields.

Basically without chitin, we wouldn’t have a lot of the materials and products we do now.

A sad side note: many horseshoe crabs are killed by fisherman as an easy source of bait and also killed by other people and used as a source of fertilizer.  There are alternatives to this, including composting food scraps and alternatives have been developed in the fishing industry to catch fish the fishermen use horseshoe crab bait for.

One of my first experiences seeing and teaching about this was finding horseshoe crab shells scattered in the local marsh.  They were all females, females are preferred, and all of them had had their insides scooped out by hand.  It was obvious because all of the insides were gone unlike with the birds the insides are pecked out.

It takes a a decade for horseshoe crabs to mature and sad they were killed for momentary pleasure.

They may be another animal that holds the key for a cure for a disease like cancer.