Spider Crab

Oncinopus araneus

Carapace rounded triangular, depressed. Posterior two pairs of ambulatory legs subchelate, last pair being subdorsal in position. Abdomen in both sexes distinctly seven-segmented. Length of carapace of an adult, 14 to 17mm. The shape of the lobes at the tip of the rostrum varies in some specimens.
Carapace elongate-triangular, thin and semi-membranous, as well as all the appendages tomentose. Rostrum short, bilobed. Eyes small, retractile beneath the edge of the carapace. No orbit or protective spines. Antennae extremely short, reaching only just beyond the tip of the rostrum. The basal joint short and free. Chelipeds in the female and young male slenderer than the next legs and not quite equal in length to the carapace; in the adult male about as stout as the next legs, with an inflated almost globose palm, and a little longer than the carapace. The 2nd and 3rd pair of legs differ very markedly from the 4th and 5th pair. The 2nd and 3rd pair are long and stout, with a comparatively slightly short carpopodite, with a long broad propodite and with a comparatively slightly curved dactylus. All these joints being remarkably setaceous. The 4th and 5th pair are slender and comparatively short. The 5th pair of legs is remarkable for its sub dorsal position.

Habitat
Inhabits the rocky, weedy bottoms, down to 50 meters deep.
Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassMalacostraca
OrderDecapoda
FamilyInachidae
GenusOncinopus
SpeciesOncinopus araneus
Photographed in
Indonesia