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Oregonia gracilis
Common Name: Decorator Crab
Size:
Up to 50 mm across at the carapace (including legs approximately 3x carapace measurement).
Description:
The carapace is light tan and almost triangular in shape with two nearly parallel rostral horns. The legs are spider-like and disproportionately large. The decorator attaches small pieces of plant, animal and hydroids to its shell for camoflauge.
Range:
Oregonia gracilis ranges from Vancouver Island, British Colombia through Washington, but are somewhat rare in Oregon and Northern California.
Habitat:
Low tidal to subtidal; sand, mud, or rock substrates.
Misidentification:
Can be confused with the Scyra acutifrons, the Sharp-Nosed crab, but Oregonia gracilis is more spider-like. The legs of Oregonis gracilis are proportionately much larger than those of the Scyra acutifrons. The Hyas lyratus, the lyre crab, can also be mistaken with Oregonis gracilis, but have very little or no decorations.
Life History:
Medium in size among spider crabs these decorators usually spawn between May and August, corresponding to the spring and summer planktonic blooms. Males reach maturity after their last molt (males at approximately 90-110mm and females at 80-100mm).
Natural History:
Oregonia gracilis lives in close proximity to other decorators (i.e. Hyas lyratus and Scyra acutifrons) and has a mutualistic relationship with hydrozoans and other corals.
Predators:
The Pacific halibut (Hippoglossus stenolepis).
Additional Resources:
Kozloff, Eugene (1996). Seashore Life of the Northern Pacific Coast. University of Washington Press: London, Ppg. 191,193,254.
Last updated Thursday, August 24, 2006, by Lisa Ferrier
