Friday, June 22, 2007

Camouflage ~ Illustration Friday

Hemigrapsus nudus or "Purple Shore Crab"

These small decapods are found in the middle-high intertidal region along the rocky shores of the Pacific. They prefer small rocks or gravel substrate and wedge themselves between larger boulders for protection when the tide has receded. In addition, they have a distinctively dark purple and reddish carapace that helps them to conceal themselves in the dark shadows, a perfect camouflage against its predators (most frequently seabirds). They make a distinctive clicking noise that is audible as you stroll along the intertidal.

Purple shore crabs and their shore crab cousins (Hemigrapsus oregonensus and Pachygrapsus crassipes) are very common residents of the intertidal and are commonly mistaken for one another as they share the same habitat. As the Hermigrapus nudus grows to around 5 cm, it spends the majority of its time feeding on algae and dead animals. Primarily an herbivore, they feed mainly on diatoms and green algae. However, as any scavenger, these crabs are essential in maintaining a stable habitat, by feeding upon other dead intertidal residents.

To see more participants in today's challenge, visit Illustration Friday.


  1. Interesting. I'm sad when I see dead ones on the tide line - the circle of life.

  2. Some of the 'dead ones' you see may actually be molts... as arthropods, they need to shed their exoskeleton as they grow. :)

  3. Okay, so why am I able to click upon some images for an enlarged view and other times I am not ??

  4. I like the distintive coloring- next time I go to the coast I'll have to look for them.
    As for the pictures, I thought it depended on the source pictures size- but not sure.

    Thenks for the kind words in your comments.

  5. Beautiful blog all over! A wonderful blog to visit-


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