hermit crab

American  

noun

1. any of numerous crabs, especially of the genera Pagurus and Eupagurus, that protect their soft uncovered abdomen by occupying the castoff shell of a univalve mollusk.

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hermit crab British  

noun

1. any small soft-bodied decapod crustacean of the genus Pagurus and related genera, living in and carrying about the empty shells of whelks or similar molluscs

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Usage

Where does the word hermit crab come from? It seems there comes a time in most every family’s life when you come home with a hermit crab, admittedly one of the least demanding pets you can have. The term hermit crab dates back to at least 1725–35. Hermit refers to the method that the crab protects itself in which it uses castoff shells. Generally speaking , a hermit is a recluse. In zoology, a hermit can refer to any animal with solitary habits. As for the word hermit itself? It ultimately comes from a Greek word meaning "living in a desert," based on the language’s noun for “desert, desolation, solitude.” The word originally referred to religious people who lived solitary lives—like off alone in the desert—in the English language. The word crab—like most of the words we've seen here—is found in Old English and has many Germanic cognates, like the dutch krab. Now that you know how the hermit crab got its name, why not find out how some of our other most beloved pets got theirs in the slideshow: "Where Do The Words For Our Pets Come From?"

Etymology

Origin of hermit crab

First recorded in 1725–35

Example Sentences

And there's a deep-sea hermit crab, living not inside a shell, but a sea star the team can't immediately identify.

From Barron's • Jan. 26, 2026

In the wild, hermit crab zoae drift with the currents, feeding on smaller plankton.

From Slate • Aug. 19, 2025

What care protocols do other hermit crab dealers follow?

From Slate • Aug. 19, 2025

There’s also the coconut crab, a type of hermit crab whose claw is so strong it can grip with a force 50 percent greater than a wolf’s jaw.

From Salon • Dec. 31, 2024

Even though I mostly spent the periods cleaning Mr. Peck’s hermit crab tanks, I liked the time with them.

From "The Benefits of Being an Octopus" by Ann Braden