Glebocarcinus

Often nestles in small holes such as dead barnacles and under rocks. Often uses its rounded carapace to block the entrance to the hole.

Geographical Range: Pribilof Islands to Palos Verdes, CA; uncommon S of Pt. Arena, CA. Common in the north but not common in the southern part of its range.

Depth Range: Intertidal to 436 m

This small cancer crab has a dark tip to its claw, the dorsal surface is covered with low tubercles, and the legs have many setae. The dorsal surface of the carpus, propodus, and dactyl of the chelipeds have prominent tubercles but no spiny ridges. Width of carapace to 5 cm, and is more nearly circular in outline than seen in other Cancer crabs. Usually a dull red as above but may be lighter in color. Underside is usually white.

How to Distinguish from Similar Species: Glebocarcinus branneri is also small but has spiny ridges and no tubercles on the chelae; plus is not as common. Lophopanopeus bellus is similar size and shape, is found in similar areas, and has black claw tips and an oval carapace but does not have the 5 teeth between the eyes characteristic of Cancer crabs, plus its carapace is often an off-white.Note: Species formerly in genus Cancer have been recently subdivided into several genera. Of our local genera, Cancer, Romaleon, and Metacarcinus have a carapace wider than long plus only scattered setae on the carapace margins and legs while Glebocarcinus has a carapace of approximately equal length and width, often with granular regions and with setae along the edges; and setae on the outer surface of the chela as well as on the legs. Metacarcinus can be distinguished from Cancer because Metacarcinus has anterolateral carapace teeth which are distinct and sharp plus the male has a rounded tip to the telson, while Cancer has anterolateral carapace teeth which are low and lobed, separated by deep fissures plus the male has a sharply pointed telson. Romaleon can be distinguished from Cancer and Metacarcinus because it has a distinct tooth on the anterior third of the posterolateral margin of the carapace while the other two genera do not.Note: Species formerly in genus Cancer have been recently subdivided into several genera. Of our local genera, Cancer and Metacarcinus have a carapace wider than long plus only scattered setae on the carapace margins and legs while Glebocarcinus has a carapace of approximately equal length and width, often with granular regions and with setae along the edges; and setae on the outer surface of the chela as well as on the legs. Metacarcinus can be distinguished from Cancer because Metacarcinus has anterolateral carapace teeth which are distinct and sharp plus the male has a rounded tip to the telson, while Cancer has anterolateral carapace teeth which are low and lobed, separated by deep fissures plus the male has a sharply pointed telson.

Biology/Natural History: This crab is very common in the intertidal zone in small spaces under and between rocks, and also subtidally in dead barnacles. It emerges at night to feed mainly on small barnacles, but also on snails, bivalves, worms, and some green algae. Is an important predator on small Japanese oysters Crassostrea gigas. Males have larger chelipeds than do females. Predators include pacific cod, and occasionally river otter and red rock crab Cancer productus. May be found in "harems" of one male and several females in their crevices, especially during the summer breeding season. Mating takes place after the females molt, and the males often carry females who are preparing to molt, and afterward until she has hardened. Ovigerous females are found in Puget Sound from November to April/May. May be infected by parasitic sacculinid barnacles. When disturbed outside its hole, this crab may fold its legs and roll like a stone.

Glebocarcinus is a genus of crabs formerly included in the genus Cancer.