Long-legged Spider Crab

• It is a decorator crab: it plants fragments of algae, sponges and hydroids on its carapace, fixed in place by hooked bristles, until it is unrecognisable.
• When it moults, it pulls its garden off the old carapace and replants it on the new one.
• It is a decorator crab: it sticks algae and debris to its carapace and legs, which are covered in hooked setae made for exactly that.
• The result is so effective that, with algae attached to its very slender legs, it passes for a strand of seaweed.
• That disguise is not only a defence: it also helps it hunt, because small fish shelter among the algae believing themselves safe. And at a pinch it can eat its own decoration.
• The carapace does not exceed about 2.8 cm, but the leg span reaches 10.
• Large crabs and deep-water ones, such as the Japanese spider crab, do not do this.

Skeleton type

Invertebrate - articulated calcareous exoskeleton (crustacean)

Habitat and environment

Algal bottoms, seagrass meadows and gravel down to about 100 m

Sources consulted: Linneo (1761) · Telnes, Marine Fauna Gallery of Norway · British Marine Life Study Society