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Hermit Crab

What is hermit crab?

· Emily Grant

Key facts

Scientific group Decapoda / Paguroidea / families Paguridae and Coenobitidae[2]
Body part protected soft abdomen[1]
Shelter used empty snail shells or other hollow objects[2]
Growth behavior changes shells as it grows[1]
Species count over 800 species worldwide[3]
Common habitat mostly ocean dwellers[3]

A hermit crab is a crab-like crustacean that protects its soft abdomen by living in an empty shell or other hollow object, and it changes shells as it grows.

Context

A hermit crab is a crab-like crustacean that lives in an empty shell or other borrowed object because its abdomen is soft and not fully protected by a hard shell [1]. As it grows, it often changes to a larger shell [1]. Hermit crabs belong to the decapod group and are placed in the superfamily Paguroidea, which includes families like Paguridae and Coenobitidae [2]. They are not true crabs in the strict biological sense; instead, they are more closely related to certain lobsters [3]. Their shells are borrowed from other animals, such as whelks or periwinkles [2]. Without a shell, they are vulnerable to predators [2]. Over 800 species exist worldwide, and most live in the ocean [3]. Some sources describe them as social and sometimes living in groups [3]. A related species is the coconut crab, which is a land-dwelling hermit crab that does not use a shell as an adult.

Documented claims

  • Hermit crabs are not true crabs in the strict biological sense. [3]
  • They are more closely related to certain kinds of lobsters than to true crabs. [3]
  • Their shells are borrowed from other animals, such as whelks or periwinkles. [2]
  • Without a shell, they are vulnerable to predators. [2]

Related

King CrabKing crabs are large marine crabs that readers may want to compare with hermit crabs.Horseshoe CrabHorseshoe crabs are often confused with hermit crabs due to similar names and habitats.

Questions and answers

Is a hermit crab a good pet?

Hermit crabs can be kept as pets, but they need proper care, including a suitable habitat and shells to change into as they grow [1].

Are hermit crabs hard to keep alive?

Keeping hermit crabs alive requires attention to their needs, such as providing shells and a safe environment, because without a shell they are vulnerable to predators [2].

Is it better to have 1 or 2 hermit crabs?

Some sources describe hermit crabs as social and sometimes living in groups, so having more than one may be beneficial [3].

Sources

  1. Hermit Crab Definition - Scottish Sensory Centre — ssc.education.ed.ac.uk (retrieved August 3, 2026)
  2. HERMIT CRAB | definition in the Cambridge English Dictionary — dictionary.cambridge.org (retrieved August 3, 2026)
  3. HERMIT CRAB Definition & Meaning — dictionary.com (retrieved August 3, 2026)

Sources last checked August 3, 2026. · More in Nature