Illustration by: Emily Stefansson
Scientific Name Cancer productus
Common Name(s) Red Rock Crab, Red Crab
Hatitats Rocky low intertidal to 260’ deep
Distribution Alaska USA to Baja Mexico
Abundance in Puget Sound Common
Scientific Name Cancer gracilis
Common Name(s) Slender crab, Graceful crab
Hatitats Sand-mud, intertidal to 470’ deep
Distribution Alaska USA to Baja Mexico
Abundance in Puget Sound Common
Scientific Name Carcinus maenas
Common Name(s) European green crab
Hatitats Multiple substratum, intertidal
Distribution Global
Abundance in Puget Sound Common
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Illustration by: Lizzie Wackenhut
Scientific Name SynomymsCancer productus None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Cancridae
Similar speciesCancer gracilis (Slender Crab)
Distinguishing CharactersTips of the claws are black, whereas the tips of C. gracilis are white.
Natural History InformationLike all other Cancers it is a carnivorous species that possesses heavy powerful claws for breaking open barnacles and other bivalves, which it most commonly preys upon.
Scientific Name SynomymsCancer gracilis None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Cancridae
Similar speciesCancer productus (Red Rock Crab)
Distinguishing CharactersTips of its claws are white, as well as the tips of its carapace teeth, whereas Cancer productus has black tipped claws and no white on its carapace teeth.
Natural History InformationThe larvae and juveniles of this species are often found clinging to jellyfish, both stealing food from the jellies and eating parasitic amphipods. The adults typically prey on barnacles and bivalves.
Scientific Name SynomymsCarcinus maenas None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Portunidae
Similar speciesCarcinus aestuarii
Distinguishing CharactersIts carapace possesses bumps that are not present on the Carcinus aestuarii carapace.
Natural History Information Infamous as a voracious predator it eats everything from bivalves, crabs, isopods, snails, and polychaetes to algae. Originally native to the North East Atlantic it has spread all over the globe and is a prominent invasive of the west coast of the United States.
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Robert Potts © California Academy of Sciences
Illustration by: Lizzie Wackenhut
Scientific Name Hemigrapsus nudus
Common Name(s) Purple shore crab
Hatitats Under rocks, intertidal
Distribution Alaska to Bahia de Tortuga, Mexico
Abundance in Puget Sound Common
Scientific Name Pachygrapsus crassipes
Common Name(s) Striped shore crab
Hatitats Upper to mid intertidal
Distribution East Pacific coast, Japan and Korea
Abundance in Puget Sound Rare
Scientific Name Cancer oregonensis
Common Name(s) Pygmy rock crab
Hatitats Low intertidal to subtidal
Distribution Alaska to Los Angeles, CA USA
Abundance in Puget Sound Common
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Scientific Name Synomyms Hemigrapsus nudus Pseudograpsus nudus, Heterograpsus nudusTaxonomy (Phylum, Subphylum, Class, Order, Family)
Arthropoda, Crustacea, Malacostraca, Decapoda, GrapsoideaSimilar species
Pachygrapsus crassipes (Striped Shore Crab)Distinguishing Characters
Chelipeds have distinct dark purple spots, whereas Pachygrapsus crassipes has no spotting on its chelipeds. Natural History Information
It osmoregulates and can therefore tolerate a wide range of hypo to hyperosmotic waters.
Scientific Name SynomymsPachygrapsus crassipes None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Grapsoidea
Similar speciesHemigrapsus nudus (Purple Shore Crab)
Distinguishing CharactersDistinct transverse lines on the carapace and legs, whereas Hemigrapsus nudus is completely lacking in stripes on its body.
Natural History InformationLives very high in the intertidal and is semi-terrestrial, spending about half of its time out of water. Feeds of small intertidal invertebrates especially limpets, dead organisms and algae.
Scientific Name SynomymsCancer oregonensis None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Cancridae
Similar speciesLophopanopeus bellus (Black-Clawed Crab)
Distinguishing CharactersDark red, round carapace, approximately 2 inches wide with several teeth on each side, whereas only 3 teeth are present on L. bellus; hairy legs; black-tipped claws.
Natural History Information Males of this species carry females around before molting as a courtship behavior, and continue to do so until their shells have hardened, even after mating.
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Illustration by: Emily Stefansson & Lizzie Wackenhut
Scientific Name Cancer magister
Common Name(s) Dungeness crab
Hatitats Low intertidal to subtidal (759’)
Distribution Alaska to Santa Barbara, CA USA
Abundance in Puget Sound Common
Scientific Name Cancer antennarius
Common Name(s) Brown rock crab, Pacific rock crab
Hatitats Upper intertidal
Distribution Alaska USA to Baja Mexico
Abundance in Puget Sound Rare
Scientific Name Lophopanopeus bellus
Common Name(s) Black-clawed crab
Hatitats Low intertidal to subtidal (264’)
Distribution B.C. Canada to Baja Mexico
Abundance in Puget Sound Common
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Illustration by: Emily Stefansson & Lizzie Wackenhut
Scientific Name SynomymsCancer magister None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Cancridae
Similar speciesCancer productus (Red Rock Crab), Cancer antennarius (Brown Rock Crab)
Distinguishing CharactersCarapace is red-brown to purple with 10 teeth on each side; up to 9 inches wide and widest at tenth tooth; claws have white tips (unlike black tips of C. productus and C. antennarius).
Natural History Information The larvae of this species usually attach to the bells of jellyfish, gaining protection from predators, as well as transportation to suitable habitats. This species is also very important in the commercial fishing industry, accounting for over 99 percent of harvested crabs.
Scientific Name SynomymsCancer antennarius None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Cancridae
Similar speciesCancer productus (Red Rock Crab), Cancer magister (Dungeness Crab)
Distinguishing Characters11 teeth on each side of the carapace, whereas C. productus has 10 teeth; carapace is widest at eighth tooth, usually no more than 5 inches wide; rough, hairy legs (unlike C. magister and C. productus); long antennae; black-tipped claws.
Natural History InformationMales of this species place a spermatophore inside the female during mating, which can then be used for multiple spawnings.
Scientific Name SynomymsLophopanopeus bellus None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Xanthidae
Similar speciesCancer oregonensis (Pygmy Rock Crab)
Distinguishing CharactersCarapace variable color, ranging from purple to orange to white, approximately 1.5 inches wide; 3 teeth on each side of carapace; black-tipped claws; no hair on legs (unlike C. oregonensis).
Natural History Information Females usually have two broods of young each year, each containing anywhere from 6,000 to 36,000 eggs.
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Scientific Name Hemigrapsus oregonensis
Common Name(s) Green shore crab, Hairy shore crab
Hatitats High to low intertidal
Distribution Alaska USA to Baja Mexico
Abundance in Puget Sound Very common
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University
Scientific Name SynomymsHemigrapsus oregonensis None
Taxonomy (Phylum, Subphylum, Class, Order, Family)Arthropoda, Crustacea, Malacostraca, Decapoda, Grapsidae
Similar speciesHemigrapsus nudus (Purple Shore Crab)
Distinguishing CharactersCarapace wider than long, somewhat rectangular, and usually no more than 2 inches wide; hairs present on legs, unlike H. nudus; usually green to gray in color, but sometimes white or spotted when young.
Natural History InformationThis species can withstand hypoxic conditions much better than other species of shore crabs. It also often has a parasitic isopod (Portunion conformis), which can only be seen through dissection.
Field Guide for the Salish Sea Intertidal Predatory Crabs
Emily StefanssonLizzie Wackenhut
© 2008 Western Washington University