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Pugettia producta
Common name(s): Shield-backed crab, kelp crab, northern kelp crab
Size:
Up to 130mm (across the top of the carapace anterior to posterior).
Range:
Intertidal to 75m deep. This crab is very common to the Puget Sound and is found from Alaska to Baja California.
Habitat:
P. Producta most often is found in eelgrass, kelp beds, or on pilings, but may also be found on rocky shores.
Identification:
Olive to reddish brown with darker spots, with lighter ventral side. The carapace is smooth, squarish, and extends forward to form a v-shaped beak and spines to the inside of eye sockets. The distance between sockets is generally one-third the total width of the carapace. The carapace generally resembles a shield, and has two predominant supra orbital spines, or "rostral horns," on the right and two on the left side of its carapace.
Healthy specimens rarely have anything growing on them, so if the carapace is overgrown by seaweeds or hydroids this is an indication that the crab has not been able to molt normally (Kozloff, 2000).
Misidentification:
P. producta may be confused with P. gracilis except that the later is much smaller in size, generally shorter than an inch. P. gracilis also has a more rounded and less squared carapace.
Natural History:
P. producta may alter its coloration to more closely match that of its surroundings. This change is hypothesized to be caused by modification of its diet, and can be manifested after it molts its old carapace and exoskelatal structures. P. producta is a nocturnal vegetarian; however, when kelp beds die back in winter months, P. producta will feed upon barnacles, hydroids, and bryozoans.
Predators:
Seabirds, sculpins, and sea otters.
Additional Resources:
Kozloff, Eugene. Seashore Life of the Northern Pacific Coast. University of Washington Press: Seattle and London.
Last updated Thursday, August 24, 2006, by Lisa Ferrier
