Puget Sound King Crab - Lopholithodes mandtii

Found in coastal waters from Southern Alaska to Central California, the Puget Sound King Crab, Lopholithodes mendtii, is a mottled, rather dull, purple and orange crab, usually well-camoflaged among the encrusting animals and algae covering rocks in its habitat. But wait!, what is going on with the outstanding individual seen here? The answer lies in the process of aging. Juvenile L. mendtii crabs are typically brilliant orange, but as they mature they change to more subtle colors. Studies of this subtidal species have not yet revealed how bright coloration confers a survival advantage to the growing animals.

Crabs belong to one of the main groups of crustacean arthropods, the Decapoda, meaning "ten feet". This species belongs to a group of crabs known as Lithode Crabs, and they are distinguished from the "true crabs" (Brachyura) by having eight visible legs/claws rather than than the ten showing in true crabs. Other groups of crabs include the hermit crabs, porcelain crabs, and galtheid crabs (squat lobsters).

For a visual overview of the Arthropods, get our program Branches on the Tree of Life: Arthropods. The DVD includes an extensive collection of still images for use in lectures, reviews and discussions, and as images in the classroom or lab to show the diversity of this group.