Glebocarcinus oregonensis (Dana), Schweitzer and Feldmann, 2000)Common name(s): Pygmy rock crab, Hairy cancer crab, Oregon cancer crab, Oregon rock crab |
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| Synonyms: Cancer oregonensis, Trichocera oregonensis, Platycarcinus recurvidens, Trichocarcinus oregonensis, Trichocarcinus recurvidens, Trichocarcinus walkeri |  |
| Phylum Arthropoda
Subphylum Crustacea Class Malacostraca Subclass Eumalacostraca Superorder Eucarida Order Decapoda Suborder Pleocyemata Infraorder Brachyura Family Cancridae |
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| Glebocarcinus oregonensis. Numbers on scale are centimeters. | |
| (Photo by: Dave Cowles, July 2005) | |
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.
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
Habitat: Often nestles in small holes such as dead barnacles and under rocks. Often uses its rounded carapace to block the entrance to the hole.
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 (photo). 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.
General References:
Harbo,
1999
Jensen,
1995
Johnson
and Snook, 1955
Kozloff,
1993
McConnaughey
and McConnaughey, 1985
Morris
et al., 1980
Niesen,
1997
O'Clair
and O'Clair, 1998
Ricketts
et al., 1985
Sept,
1999
Scientific Articles:
Some individuals are lighter colored, as this individual. Numbers
on scale are centimeters. Photo by Dave Cowles, July 2005.
Front-on view. Note the tubercles on the dorsal margins of the
chelipeds
The many setae are most evident when the animal is underwater, as in
this picture.
This species often nestles in holes in rocks, as seen in this photo
from Cape Flattery, WA. Often a male and female nestle in the same
hole.
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| Some Glebocarcinus oregonensis, especially larger and deepliving individuals, seem to have a very pronounced pattern clusters of raised tubercles on the carapace. This individual was caught at 100 m depth in the San Juan Channel. | Here is a closeup of the two patches of tubercles from the individual to the left, just behind the head. The tubercles appear to be an integral part of the exoskeleton but are sharply raised above it. As a whole, the size and shape of the individual tubercles reminds me of the bumps present on the large chelae of the lithodid crab Oedignathus inermis. I wonder whether they are simply raised portions of the carapace or actual thickenings, and whether they may function to make the exoskeleton stronger and more crush-proof. |