Oregonia gracilis Dana, 1851
Common name(s): Graceful decorator crab
Infraorder Brachyura (true crabs)
|Oregonia gracilis, Two Harbors, CA. Carapace 3 cm long.|
|(Photo by: Dave Cowles May 1997)|
How to Distinguish from Similar Species: This is the only decorator crab with the long hooked spine behind the eye. The carapace does not have a sharp anterolateral projection as seen in Pugettia producta.
Geographical Range: Bering sea to Monterey, CA; Japan
Depth Range: Intertidal to 436 m deep
Habitat: Most abundant on mixed composition bottoms
Biology/Natural History: This crab decorates more liberally than any of the other decorator crabs in this area. During decoration, pieces of material are attached to specialized hooked setae and also interact with pappose setae. The crab's chelae are small and delicate. In males the chelipeds are longer than the walking legs, but in females they are shorter. Will eat carrion. Predators include Pacific halibut (Hippoglossus stenolepis). In Puget Sound area, eggs may be carried during most seasons. Recently hatched eggs are orange-red; eggs nearly ready to hatch are reddish-brown.
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Berke, Sarah K. and Sarah A. Woodin, 2009. Behavioral and morphological aspects of decorating in Oregonia gracilis (Brachyura Majoidea). Invertebrate Biology 128:2 pp 172-181
This Oregonia gracilis is festooned with hydroids and (tunicates?). From 100 m depth, San Juan Channel. Photo by Dave Cowles, July 2001
Here is the underside of another individual. Note the long, thin legs and chelipeds, and the long hydroid attached to the rostrum. Photo by Dave Cowles, July 2005