What kinds of animals are crabs?

Crabs are decapod crustaceans that include true crabs (Brachyura) and related groups within Anomura, such as hermit crabs and allies.

How big do crabs get?

Sizes range from pea crabs only a few millimetres wide to the Japanese spider crab with a leg span up to 4 m (13 ft).

Many crabs are marine omnivores; others are specialist herbivores or carnivores, and some are parasitic; some species live in freshwater or non-marine habitats.

Crabs commonly hide in rocky crevices.

Are crabs important to people?

Crabs make up about 20% of the marine crustaceans caught or farmed for human consumption and feature in cuisine, mythology, art, and as pets.

What does ‘carcinisation’ mean?

Carcinisation is the evolutionary process by which varied decapods have independently evolved a crab-like body plan.

Are hermit crabs true crabs?

Hermit crabs belong to groups within Anomura and are related to, but distinct from, the true crabs of Brachyura.

Where to See Crab While Diving

Q: Do crabs always live in the sea?

While many crabs are marine, a substantial number of species are adapted to freshwater or other non-marine habitats.

Crabs are decapod crustaceans that include the true crabs (Brachyura) and various related groups within the Anomura (such as hermit crabs and allies). They are characterised by a heavily armoured shell, tail segments concealed beneath the body, the ability to run sideways, and a habit of hiding in rocky crevices. Crabs do not form a single natural group; they have evolved the crab-like body plan multiple times from ancestral decapods through a process called carcinisation, making the group polyphyletic. Size varies widely across species, from pea crabs a few millimetres wide to the Japanese spider crab with a leg span up to 4 m (13 ft). Many crabs are free-living marine omnivores, while others are specialist herbivores, carnivores, or parasitic; a substantial number of species are adapted to freshwater or other non-marine habitats. Crabs are significant in human culture and cuisine, are kept as pets (hermit crabs), and appear in mythology and art.

Many crabs are capable of running sideways and commonly hide in rocky crevices.

Diet varies by species: many are free-living marine omnivores; others are specialist herbivores, carnivores, or parasitic; some inhabit freshwater or non-marine environments.

The strongest linked planning options currently surface around destinations such as Caye Caulker, San Pedro (Ambergris Caye), Belize, Zeeland (Oosterschelde and Grevelingenmeer) and countries such as Belize, Spain, Netherlands for divers building trips around crabs.