Spanner Crab

• Unlike almost all crabs, it walks and swims forwards and backwards rather than sideways.
• It buries itself backwards into the sand within seconds using its paddle-shaped hind legs.
• Its shape is unique among crabs: the body is elongated and tapers towards the rear, not broad and flattened, and the abdomen remains partly extended instead of folded beneath the body.
• That anatomy is an adaptation for digging: it buries itself backwards in the sand in a matter of seconds, pushing with legs transformed into shovels.
• It walks and swims forwards, not sideways like almost all crabs.
• It is a prized delicacy in Japan, the Philippines, Australia and Hawaii, with dedicated fisheries in several of those regions.
• It hunts by ambush: buried, with its eyes poking out, it seizes fish and crustaceans passing nearby.
• Its name, ranina, alludes to the resemblance of its head to a frog's.

Skeleton type

Invertebrate - chitin exoskeleton (crustacean)

Habitat and environment

Shallow sandy bottoms of the Indo-Pacific

Sources consulted: FAO Species Catalogue; Museo Australiano; Skinner y Hill, trabajos sobre Ranina ranina