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Shore Crabs: More Information

Description: Shore crabs are compact and flat, with a nearly square back and legs that tuck tightly together and against the body.  Our three species are generally dark and subtly patterned:  fine, green stripes across the back from side to side; purple mottling on the back and spots on the claws; mottled greenish gray all over.  Small (up to 2” wide) and very active, these crabs scuttle about when not hiding under rocks and in crevices.

What kind of shore crab did you find?  Examine the colors and think about the location of the shore crab:

Fine green lines across the back and high on the shore?  lined shore crab

Purple spots on the claws and a bit lower on the shore?  purple shore crab

Mottled greenish gray and still lower on the shore?  Oregon shore crab

Taxonomy:

  Kingdom Animalia  -- Animal, animals, animaux  
     Phylum Arthropoda  -- arthropodes, arthropods, Artrópode  
        Subphylum Crustacea Brünnich, 1772 -- crustaceans, crustáceo, crustacés  
           Class Malacostraca Latreille, 1802  
              Subclass Eumalacostraca Grobben, 1892  
                 Superorder Eucarida Calman, 1904 -- camarão, caranguejo, ermitão, lagosta, siri  
                    Order Decapoda Latreille, 1802 -- crabes, crabs, crayfishes, crevettes, écrevisses, homards, lobsters, prawns, shrimp  
                       Suborder Pleocyemata Burkenroad, 1963  
                          Infraorder Brachyura Latreille, 1802 -- short-tailed crabs, true crabs

Common species:

Hemigrapsus nudus (Dana, 1851) -- purple shore crab

Hemigrapsus oregonensis (Dana, 1851) -- yellow shore crab, Oregon shore crab

Pachygrapsus crassipes J. W. Randall, 1840 -- striped shore crab

Taxonomic information source: ITIS.gov