Atlantic Spinous Spider Crab

Description

It is red, brownish-red, or yellowish in colour and the body is up to 20 cm long. It has a circular to oval shell (carapace), broad at the back and narrow at the front. Strong tapering spines border the shell, while the rest of the shell bears smaller spines. The small eyes are either side of two distinct frontal spines. The legs are covered by hairs. The first pair of legs bear small claws while the rest taper to stout, dark tips. The shell is usually covered with algae.

Distribution

Eastern Atlantic: from the North Sea to Morocco and Bay of Biscay.

Habitat and biology

Juveniles about to reach maturity live in shallow waters from 10 to 15 m deep on rocky and sandy substrates. They are also found on sandy bottoms colonized by Zostera marina. During summer, adults live near the shore on rocky areas. In winter, they are spotted on rocky bottoms and heterogeneous coarse sediments in deep waters. Both juveniles and adults during summer are found on muddy sands with few rocks. Uses slow, small-scale, non-directional movements. Exhibiting ontogenetic movements, juveniles live at depth of 5 to 15 m; adults then migrate to deeper waters (>50 m), where they mate. Diet remains to be accurately described. Studies (i.e. direct field observations, laboratory experiments, and gut content analyses) have suggested the species to have an omnivorous diet based on consumption of prey commonly found in their habitat. In one study, however, it was considered a mobile carnivorous species. Research using stable isotopes indicate no differences between sexes in diet or habitat use patterns either in adults or juveniles. Members of the order Decapoda are mostly gonochoric. Mating behavior: Precopulatory courtship ritual is common (through olfactory and tactile cues); usually indirect sperm transfer.