Butterfly crab • Cryptolithodes typicus
Identification
The laterally expanded carapace of this crab hides its legs and claws from view, so that when viewed from above the crab may appear like a rock or a piece of bivalve shell. The carapace colour varies greatly from drab and dark to vibrant or white, and may or may not be uniform: it may be mottled, streaked, or speckled, or the central portion may contrast with the sides, creating the effect of a butterfly's wings. The butterfly crab gets to 8 cm wide.
Habitat & Range
The butterfly crab is found along rocky shorelines from the low intertidal to and subtidal to depths of 55 m. Its is found in exposed locations as well as more protected habitats with high currents. It hides in crevices and on rock covered with encrusting algae and animals; when the crab remains still it can blend in with these surroundings quite successfully. The butterfly crab's range extends from northern Alaska to southern California.
Similar Species
The butterfly crab can be differentiated from the similar umbrella crab (Cryptolithodes sitchensis) by a few key characteristics. The butterfly crab's claws are roughened with tubercles, its abdominal plates have raised edges, and its rostrum is widest at the base. In contrast, the umbrella crab has smooth claws and abdominal plates, and its rostrum widens or flares at the tip. Additionally, the umbrella crab is restricted in habitat to exposed outer coastlines.
iNaturalist
https://www.inaturalist.org/taxa/53845-Cryptolithodes-typicus
The laterally expanded carapace of this crab hides its legs and claws from view, so that when viewed from above the crab may appear like a rock or a piece of bivalve shell. The carapace colour varies greatly from drab and dark to vibrant or white, and may or may not be uniform: it may be mottled, streaked, or speckled, or the central portion may contrast with the sides, creating the effect of a butterfly's wings. The butterfly crab gets to 8 cm wide.
Habitat & Range
The butterfly crab is found along rocky shorelines from the low intertidal to and subtidal to depths of 55 m. Its is found in exposed locations as well as more protected habitats with high currents. It hides in crevices and on rock covered with encrusting algae and animals; when the crab remains still it can blend in with these surroundings quite successfully. The butterfly crab's range extends from northern Alaska to southern California.
Similar Species
The butterfly crab can be differentiated from the similar umbrella crab (Cryptolithodes sitchensis) by a few key characteristics. The butterfly crab's claws are roughened with tubercles, its abdominal plates have raised edges, and its rostrum is widest at the base. In contrast, the umbrella crab has smooth claws and abdominal plates, and its rostrum widens or flares at the tip. Additionally, the umbrella crab is restricted in habitat to exposed outer coastlines.
iNaturalist
https://www.inaturalist.org/taxa/53845-Cryptolithodes-typicus
References
Cowles, D. (2005). Cryptolithodes typicus Brandt, 1849. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 03/07/2015.
Hart, J. (1984). Cryptolithodes typicus Brandt, 1849. In Klinkenberg, Brian. (Editor). E-Fauna BC: Electronic Atlas of the Fauna of British Columbia. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. Accessed 03/07/2015.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 302.
Jensen, G.C. (1995). Pacific Coast Crabs and Shrimp. Monterey, CA: Sea Challengers. P. 71.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2015).
Cowles, D. (2005). Cryptolithodes typicus Brandt, 1849. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 03/07/2015.
Hart, J. (1984). Cryptolithodes typicus Brandt, 1849. In Klinkenberg, Brian. (Editor). E-Fauna BC: Electronic Atlas of the Fauna of British Columbia. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. Accessed 03/07/2015.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 302.
Jensen, G.C. (1995). Pacific Coast Crabs and Shrimp. Monterey, CA: Sea Challengers. P. 71.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2015).