Purple shore crab

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Purple shore crab
Hemigrapsus nudus 3043.JPG
Scientific classification
H. nudus
Binomial name
Hemigrapsus nudus
(Dana, 1851)

The purple shore crab, Hemigrapsus nudus, is a common crab of the family Varunidae. It can be found sheltering under rocks in inter-tidal areas along the west coast of North America, from Alaska to Baja California in Mexico.[1] This crab primarily eats sea lettuce and other green algae, and occasionally scavenges dead animals.[2]


A small crab, H. nudus reaches sizes of approximately 4.0–5.6 centimetres (1.6–2.2 in).[1] Its dorsal shell (carapace) is generally a dark purple in color, although it may be olive green or red, with white or cream markings. The color of the legs matches the color of the carapace but the white-tipped claws (chelipeds) are a lighter color with purple or red spots – these spots allow H. nudus to be distinguished from a similar looking crab, the lined shore crab, Pachygrapsus crassipes, whose chelipeds lack spots.[3] The legs of H. nudus lack setae, a distinguishing feature of the otherwise similar H. oregonensis.


  1. ^ a b Kwasi Addae. "Hemigrapsus nudus". The Evergreen State College. Archived from the original on August 5, 2010. Retrieved November 4, 2010.
  2. ^ "Hemigrapsus nudus The Purple Shore Crab". Intertidal Marine Invertebrates of the South Puget Sound. Archived from the original on May 9, 2008. Retrieved November 4, 2010.
  3. ^ James Watanabe (March 11, 2010). "Phylum Arthropoda, Subph. Crustacea: Rocky Shore Crabs, Shrimp, Isopods, Amphipods". SeaNet: Common Marine Organisms of Monterey Bay, California. Stanford University. Retrieved November 4, 2010.

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