Sharp-nosed crab, sharpnose crab • Scyra acutifrons
Identification
This crab's distinct rostrum is composed of two flat, leaf-shaped horns with divergent tips. The rostrum is widest at the middle of its length. The carapace is roughly a triangular shape, and its surface is irregular and bumpy. The carapace is brownish, brownish-red, brownish-purple, or tan, but this colour is often covered by sponges, bryozoans, and other growths. The crab's walking legs are relative short and stout, and its claws are long and slender — especially those of adult males. The claws usually have orange markings. The sharp-nosed crab grows to 4.5 cm wide.
Habitat and Range
The sharp-nosed crab lives in rocky areas in the low intertidal and subtidal to a depth of 216 m. They are most common in exposed subtidal areas with abundant invertebrate diversity rather than algae-dominated areas. Its range stretches from Kodiak Island, Alaska to San Carlos Point in Mexico.
Similar Species
Sharp-nosed crabs can be confused with juvenile moss crabs (Loxorhynchus crispatus); adult moss crabs are more than twice the size of a sharp-nosed crab and so can't be confused. The most crab has a straight-edged rostrum that has blunt ends instead of the divergent pointed tips of the aptly-named sharp-nosed crab. The sharp-nosed crab's rostrum is obviously longer than it is wide, whereas the moss crab's rostrum is noticeably shorter. Moss crabs are covered in setae, and are more active decorators (as seen in this Monterey Bay Aquarium photo). Moss crabs are also much less common; in fact, their presence wasn't noted north of California until the 1990's. This range expansion may be the result of temperature changes from multiple El Niño events.
Intriguing Info
The sharp-nosed crab is often decorated, but puts little effort into doing so. Usually sponges, bryozoans, and other growths colonize its rough carapace on their own, though the crab may add a bit of material on to its rostrum (which could potentially impact a correct identification).
iNaturalist
https://www.inaturalist.org/taxa/47712-Scyra-acutifrons
This crab's distinct rostrum is composed of two flat, leaf-shaped horns with divergent tips. The rostrum is widest at the middle of its length. The carapace is roughly a triangular shape, and its surface is irregular and bumpy. The carapace is brownish, brownish-red, brownish-purple, or tan, but this colour is often covered by sponges, bryozoans, and other growths. The crab's walking legs are relative short and stout, and its claws are long and slender — especially those of adult males. The claws usually have orange markings. The sharp-nosed crab grows to 4.5 cm wide.
Habitat and Range
The sharp-nosed crab lives in rocky areas in the low intertidal and subtidal to a depth of 216 m. They are most common in exposed subtidal areas with abundant invertebrate diversity rather than algae-dominated areas. Its range stretches from Kodiak Island, Alaska to San Carlos Point in Mexico.
Similar Species
Sharp-nosed crabs can be confused with juvenile moss crabs (Loxorhynchus crispatus); adult moss crabs are more than twice the size of a sharp-nosed crab and so can't be confused. The most crab has a straight-edged rostrum that has blunt ends instead of the divergent pointed tips of the aptly-named sharp-nosed crab. The sharp-nosed crab's rostrum is obviously longer than it is wide, whereas the moss crab's rostrum is noticeably shorter. Moss crabs are covered in setae, and are more active decorators (as seen in this Monterey Bay Aquarium photo). Moss crabs are also much less common; in fact, their presence wasn't noted north of California until the 1990's. This range expansion may be the result of temperature changes from multiple El Niño events.
Intriguing Info
The sharp-nosed crab is often decorated, but puts little effort into doing so. Usually sponges, bryozoans, and other growths colonize its rough carapace on their own, though the crab may add a bit of material on to its rostrum (which could potentially impact a correct identification).
iNaturalist
https://www.inaturalist.org/taxa/47712-Scyra-acutifrons
References
Cowles, D. (2005). Scyra acutifrons Dana, 1851. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 04/04/2014.
Harbo, R.M. (1999). Whelks to whales: Coastal marine life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 78.
Hart, J. (1984). Scyra acutifrons Dana, 1851. In Klinkenberg, Brian. (Editor) 2012. 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 04/04/2014.
Jensen, G.C. (1995). Pacific Coast Crabs and Shrimp. Monterey, CA: Sea Challengers. Pp. 21 + 24.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 304
Sanders, A. (2013). Loxorhynchus crispatus moss crab. Animal Diversity Web. Accessed 04/04/2014.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2014).
Cowles, D. (2005). Scyra acutifrons Dana, 1851. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 04/04/2014.
Harbo, R.M. (1999). Whelks to whales: Coastal marine life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 78.
Hart, J. (1984). Scyra acutifrons Dana, 1851. In Klinkenberg, Brian. (Editor) 2012. 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 04/04/2014.
Jensen, G.C. (1995). Pacific Coast Crabs and Shrimp. Monterey, CA: Sea Challengers. Pp. 21 + 24.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 304
Sanders, A. (2013). Loxorhynchus crispatus moss crab. Animal Diversity Web. Accessed 04/04/2014.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2014).