Hermit Crab Workshop

Today was our Family Science - Hermit Crab Workshop. We had about 38 participants that learned about Hermit Crabs and left with two crabs to take home as new pets. We hope that in addition to enjoying the new additions to their families, the participants will continue to talk back to us via this website. We want to know how the crabs are doing, how they are behaving, heck, send us some photos of the little critters! Check out our Hermit Crab discussion forum for the latest discussions about the crabs.

Below is some information about Hermit Crabs that our workshop participants should find useful and some photos from today. We have also included a movie of the presentation from today as well at the end of this post.

What has ten legs, lives in a mobile home with a purple door, and needs a weekly bath but never uses soap? It’s a Coenobita clypeatus (sen-uh-BID-uh klih-pee-AY-tus), also known as a land hermit crab, a purple pincher, a tree hermit crab, or a red legged hermit crab! Whew! What a lot of names for one small animal.

There are several families of hermit crabs. Those that live in the ocean are marine hermit crabs. Hermit crabs that live on land are terrestrial, or land hermit crabs.

Coenobita clypeatus is a particular species of land hermit crab. When you look closely at one of these interesting creatures, you can see why it is sometimes called the purple pincher. The largest claw, the cheliped (KEE-luh-ped), is usually a very deep purple. Likewise, if you look at the legs, you can understand why it is also called the red-legged hermit crab. These colors are more evident on some crabs than others. And, although they don’t live in trees, land hermit crabs can climb trees and almost anything else they can grip with their claws!

Where are they found?
There are over 80 species of land hermit crabs found around the world. Usually they live where it is warm, often near the ocean. The purple pincher is found from southern Florida to Bermuda and the West Indies, and farther south to Venezuela, South America. It is the only land hermit crab native to the shores of the Western Atlantic Ocean. Adult land hermit crabs rarely live right on the beach. They prefer dry ground, close to a fresh water source. They will sometimes move inland 15 kilometers (over nine miles) from the ocean.

What do they eat?
Hermit Crabs are omnivorous (ahm-NIV-or-us) scavengers. They eat just about anything, plant or animal. Some of their favorite foods are coffee grounds, rotten fruit, and decaying meat. Hermit crabs help keep the areas they live in free from dead animal carcasses and decaying vegetation. When they live close to human beings, land hermit crabs will eat from garbage dumps and drink water from leaking faucets or animal pens.

A Hermit Crab’s Home
Hermit Crabs use shells to protect their abdomens. They carry shells with them wherever they go. The shell not only protects the soft abdomen of the hermit crab, but also gives the crab a means of carrying a supply of water with them to keep their gills moist. Hermit crabs are unable grow their own shells, so they use shells from dead sea or land snails.

The Hermit Crab Anatomy
Hermit crabs have several parts that make up their body. They have segmented (divided) body parts and an exoskeleton (a hard covering on the outside of the body, rather than an internal skeleton like we have); it is identified as an arthropod (AR-thruh-pahd). Spiders and insects are also arthropods. Because it breathes with gills, and has two pair of antennae (an-TEN-ee) in front of its mouth, it is also a crustacean (krus-TA-shun), a large class of arthropods that live in, or frequently goes into, water.

Instead of having a backbone or skeleton inside its body like you do, a hermit crab has an exoskeleton made of chitin (KY-tin). When we grow, our skeletons grow with us. But a crab’s exoskeleton does not grow as the crab grows. When a crab grows too large for its exoskeleton, the exoskeleton splits open, and the crab crawls out. This is called molting. After molting, a crab’s body is very soft. It takes up to ten days for the new exoskeleton to harden.

Hermit crabs have compound eyes. This means that a hermit crab’s eye is made up of many independent light sensitive units. Instead of seeing one image like you do, a crab sees multiples of the one image.  This allows the hermit crab to detect fast movements and see in a very wide angle.

More information on Hermit Crabs

• How to Care for your Hermit Crab
• Some common questions about Hermit Crabs
• Ask questions or talk with other crab owners in the Hermit Crab discussion fourm