Wildlife Encounters: The Hermit Crab

Kayaking Along the San Diego River
January 22, 2018
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Wildlife Encounters: The Hermit Crab

So what’s the deal with hermit crabs? Some people think they’re adorable, and others would rather they not pinch their toe. The chances of toe pinching is unlikely as they would much rather crouch in their shell than pick a fight with a human. If you go to the La Jolla Tide Pools, you will most likely encounter these guys, so let’s dive into what makes them so interesting.

Part of the Family

Hermit Crabs are part of the Decapoda Crustacean family, meaning they are 10 legged marine animals with a hard exoskeleton. You’ll find crabs and lobsters fitting this definition.

Finding a Home

Hermit Crabs do not grow their own shells and often occupy abandoned snail shells to protect their vulnerable soft bellies. People have even taken the time to create fun artificial shells for them made of glass or plastic, however, they are very sensitive to metal.

They Do Grow

Hermit crabs molt and shed their exterior hard shells. During this time they are very vulnerable and often do this seasonally in groups. As they grow larger, they find larger shells to occupy. They can also regrow lost limbs. The largest of these crabs are the coconut crab in Indonesia which can grow up to 3 ft in length!

Not so Shy Afterall

They are actually incredibly social amongst themselves and can be found in herds of thousands. They will often molt together, and trade or fight for shells. Sometimes it can be seen as a cascading effect starting with one crab wanting a new shell and suddenly they are all changing homes.

What do They Actually Eat?

Like other crabs, they are scavengers. One claw is good for attacking and defending, and the other claw is good for picking and gathering their food. They’ll eat just about anything and are very adaptable to new environments.

Some People Keep Them as Pets, Is That a Good Idea?

At almost every Wings, which exist on almost every beach town, you’ll find a hermit crab section where you can buy little crabs in fun painted shells. These are terrible environments for them, so just make sure you have a real home for them if you do take them home and don’t keep them in the tiny carrier they come in. Once they are comfortable in your hand they are actually pretty fun, curious, and great climbers. Some people even go extensively into making fun Crabitats, by creating climbing spots for them in their cage. It’s important that a happy and healthy Crabitat is social with several crabs, but not overcrowded. there should be moisture that can be trapped because even terrestrial crabs use gills, but not so moist that mold grows. Place sponges in their water bowls, use clean sand, and change up their diet every now and then with special treats like tiny fruit bits.

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