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Crab

Marine life profile

Crab

Recorded at 3583 dive sites

Where divers encounter it

Explore Crab around the world

Crabs are decapod crustaceans, either the Brachyura or various groups within the closely related Anomura, characterised by having a heavily armoured shell, their tail segments concealed under the body, the ability to run sideways, and the habit of hiding in rocky crevices. Most stay close to cover, emerging to feed, clean other animals or defend a small shelter.

Dive sites3583
Countries95
Animal groupCrustaceans
Safety profileGenerally Harmless

Meet the species

What to look for

How to Recognize It

Look for a jointed shell, paired antennae and articulated legs adapted for walking, digging or gripping.

How It Behaves

Most stay close to cover, emerging to feed, clean other animals or defend a small shelter.

Special Ability

A tough external skeleton provides portable armor and is replaced as the animal grows.

Dive responsibly

Share the water well

How to Approach

Settle nearby and wait. Avoid touching antennae, claws or the shelter, especially during a night dive.

Safety

Observe without handling. Claws and defensive spines can injure, and recently molted animals are especially vulnerable.

Worth knowing

The detail you remember

Interesting Facts

They do not form a single natural group or clade, but have convergently evolved multiple times from the ancestral decapod body plan through carcinisation, the process of creating this set of characteristics.

Where to Find

Search beneath ledges, inside coral heads, around anemones and across rubble after sunset.

Known countries

SwitzerlandBonaire, Sint Eustatius and SabaAustraliaMauritiusTurkeyDominican RepublicCambodiaNetherlandsMexicoUnited StatesUnited States of America (USA)Puerto RicoEgyptMaldivesIndiaCanadaThailandGrenadaRomaniaGreece