How to Distinguish from Similar Species: At first glance this crab looks superficially like the helmet crab Telmessus cheiragonus or even like the shield-back kelp crab Pugettia producta (both Brachyurans), but can be distinguished by the wide, soft abdomen, the scale-like appearance, and the modified 5th leg characteristic of Anomurans.
Geographical Range: Pribilof Islands to Puget Sound
Depth Range: Shallow subtidal to 110 m
Habitat: Vertical rock faces and overhangs associated with Metridium senile or Metridium giganteum, among boulders.
Have been observed
eating brittle stars. Predators of this species include river
The abdomen of the female is mostly covered with plates (photo); that of the male is
with vestigial plates (photo).
Kozloff 1987, 1996
General Notes and Observations: Locations, abundances, unusual behaviors:
Another photo of the species. Dave Cowles, July 2001
Enlargements of the right and left chelae from the picture above. Dave Cowles, July 2001
The broad abdomen of this species is soft, somewhat like leather; especially in the distal yellow portion visible above. This appears to be a male abdomen. See the photos below to compare with a female abdomen. Photo by Dave Cowles, July 2001
This gravid female found subtidally on Sares Head is 7 cm across the carapace. Photo by Dave Cowles, July 2012. See more photos of her below.
The underside of this female's abdomen is soft in part of it but has a rounded, hardened shield across the tip. She is carrying eggs (see below). Photo by Dave Cowles, July 2012
This is the same female as shown above. She is highly defensive of her abdomen but the crevice seen in this view shows that she is carrying many bright orange eggs.
Authors and Editors of Page:
Dave Cowles (2005): Created original page