# Hermit Crab — Facts, Threats & Conservation

*Paguroidea*

> Hermit crabs are crustaceans that protect their soft, spiraled abdomens by living inside empty snail shells. As they grow, they leave their old shell and move into a larger one, sometimes lining up to swap shells in sequence.

**IUCN status:** Least Concern  ·  **WARN range:** Oceans

## Quick facts
| Fact | Value |
| --- | --- |
| Scientific name | Paguroidea (superfamily) |
| Diet | Omnivore (algae, plankton, scraps, carrion) |
| Habitat | Shorelines, tide pools, and seabeds worldwide |
| Lifespan | 10–30 years (varies by species) |
| Size | From a few millimeters to 30 cm (coconut crab) |
| Top speed | Slow walkers; faster when alarmed |
| Conservation status | Least Concern (IUCN, most species) |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Arthropoda
- **Class:** Malacostraca
- **Order:** Decapoda
- **Family:** Paguridae

## Conservation status
- **Status:** Least Concern (IUCN Red List category)
- **Population:** Global population not compiled for this guide
- **Trend:** See the IUCN Red List assessment
- **Assessed:** See the IUCN Red List assessment
- **CITES:** See CITES appendices
- Conservation figures are drawn from the IUCN Red List and CITES; this guide links to the authoritative sources rather than restating population counts.

## Key facts: Hermit Crab
- Unlike true crabs, most hermit crabs have a soft, curled abdomen with no hard shell of its own.
- As a hermit crab grows it outgrows its shell and must find a larger one.
- Hermit crabs are omnivorous scavengers that feed on algae, plankton, food scraps, and dead animals, helping clean the shoreline.

## Borrowed homes
Unlike true crabs, most hermit crabs have a soft, curled abdomen with no hard shell of its own. To protect it, the crab backs into an empty snail shell and carries it everywhere, gripping the inside with specially shaped rear legs. The shell shields the crab from predators and from drying out.

## Shell swapping
As a hermit crab grows it outgrows its shell and must find a larger one. When a good empty shell appears, crabs sometimes gather and form a line by size, each moving into the next-biggest shell in a chain swap. Competition for shells can be intense where suitable shells are scarce.

## Diet and behavior
Hermit crabs are omnivorous scavengers that feed on algae, plankton, food scraps, and dead animals, helping clean the shoreline. They are mostly active at night and use their antennae and claws to find and handle food. Many species are social and gather in groups, especially around food or fresh shells.

## As a pet
Land hermit crabs are common, inexpensive pets that need humid, warm enclosures, a choice of empty shells to grow into, and both fresh and salt water. With good care they can live well over a decade, far longer than many owners expect. They are wild-caught in some regions, so responsible sourcing matters.

## What WARN does
WARN does not run a dedicated hermit crab programme — this guide is part of the World Animal Rescue Network's free educational library. The hermit crab is currently widespread and not globally threatened, and this guide helps readers understand the pressures that can change that. Building public understanding of species like the hermit crab supports the broader conservation awareness that underpins WARN's partner-led rescue work across its network.

If clear, science-based wildlife guides like this help you understand and value animals, please consider supporting the World Animal Rescue Network's educational and rescue work so we can keep producing them.

## Frequently asked questions: Hermit Crab
### Why do hermit crabs live in shells?
Most hermit crabs have a soft, vulnerable abdomen and no shell of their own, so they move into empty snail shells for protection from predators and from drying out.

### Do hermit crabs change shells?
Yes. As they grow, hermit crabs must move into larger empty shells. They sometimes gather and line up by size to swap shells in a chain, each taking the next-biggest one.

### What do hermit crabs eat?
Hermit crabs are omnivorous scavengers. They eat algae, plankton, food scraps, and dead animals, which makes them useful cleaners of the shoreline.

### Are hermit crabs good pets?
Hermit crabs can make low-cost, low-maintenance pets, but they need a warm, humid tank, spare shells to grow into, and both fresh and salt water. With proper care they can live for over a decade.

### Are hermit crabs actually crabs?
Hermit crabs are crustaceans closely related to true crabs but in a different group. Unlike true crabs, they have a soft, asymmetrical abdomen that they protect inside a borrowed shell.

### Where do hermit crabs live?
Hermit Crabs live in Shorelines, tide pools, and seabeds worldwide. Hermit crabs are crustaceans that protect their soft, spiraled abdomens by living inside empty snail shells. As they grow, they leave their old shell and move into a larger one, sometimes lining up to swap shells in sequence.

### Are hermit crabs dangerous?
Hermit Crabs are not generally dangerous to people. Hermit crabs are crustaceans that protect their soft, spiraled abdomens by living inside empty snail shells. As they grow, they leave their old shell and move into a larger one, sometimes lining up to swap shells in sequence. Give wild individuals space and do not corner or handle them.

### How long do hermit crabs live?
Hermit Crabs typically live 10–30 years (varies by species). Hermit crabs are crustaceans that protect their soft, spiraled abdomens by living inside empty snail shells. Wild and captive figures can differ; use the sources listed on the guide for the underlying studies.

### How big is a hermit crab?
A Hermit Crab is about 10–30 years (varies by species). Hermit crabs are crustaceans that protect their soft, spiraled abdomens by living inside empty snail shells. As they grow, they leave their old shell and move into a larger one, sometimes lining up to swap shells in sequence. Conservation status: Least Concern (IUCN, most species).

## Sources
- [Wikipedia — Hermit Crab](https://en.wikipedia.org/wiki/Hermit_crab)
- [Wikidata — Hermit Crab](https://www.wikidata.org/wiki/Q273291)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/hermit-crab