Graceful Kelp Crab

Pugettia gracilis

Graceful Kelp Crab

Pugettia gracilis

Other Common Names
Graceful rock crab, Slender kelp crab

Sandy Coast

Other Common Names

Graceful rock crab, Slender kelp crab

At the Aquarium

Sandy Coast

Appearance

These crabs can come in variable colors, most often in browns, yellows, or reds, while the claws have dark blue fingers with orange or red at the very tip. The carapace is ¾ to 1.5” across, has 2 spines on the upper back, and is relatively smooth, with a few large bumps.

Habitat

Low intertidal on rocky shores and subtidally in kelp beds and eelgrass meadows. Juveniles often hang out in eelgrass.

Diet

Omnivores, kelp, snails

Life History

The Graceful kelp crab has a terminal molt upon reaching sexual maturity, and no longer grows after this point. They reproduce in June and July, and females brood their red-orange eggs on their abdomens. A female can carry up to 84,000 eggs per season.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

They serve as food for their predators including halibut, clingfish, kelpfish, and woolly sculpin. They may impact the kelp forests where they live. Graceful kelp crabs eat kelp and might negatively impact bull kelp’s growth, but they also feed on herbivorous, kelp-eating snails, helping maintain a balance.

Alaska to California

During a very low tide you might be lucky enough to come across a graceful kelp crab while tidepooling.

Like other crabs, you can tell the sex of a kelp crab by inspecting the abdomen. Males have a narrow, triangular abdomen while a female’s abdominal flap is more rounded. Kelp crabs are in the superfamily Majoidea, the spider or decorator crabs. Graceful kelp crabs do have some hooked setae on their shell for attaching decorations but they are only considered minimal decorators.

Citations & Other Resources

Biodiversity of the Central Coast website: https://www.centralcoastbiodiversity.org/graceful-kelp-crab-bull-pugettia-gracilis.html
Dobkowski, Katie. “The role of kelp crabs as consumers in bull kelp forests—evidence from laboratory feeding trials and field enclosures.” PeerJ 5 (2017): e3372.
Invertebrates of the Salish Sea website: https://inverts.wallawalla.edu/Arthropoda/Crustacea/Malacostraca/Eumalacostraca/Eucarida/Decapoda/Brachyura/Family_Majidae/Pugettia_gracilis.html
National Marine Sanctuary Foundation website: https://marinesanctuary.org/blog/sea-wonder-kelp-crab/
Hultgren, K. M., and J. J. Stachowicz. “Evolution of decoration in majoid crabs: a comparative phylogenetic analysis of the role of body size and alternative defensive strategies.” The American Naturalist 173.5 (2009): 566-578.

Graceful Kelp Crab

Graceful Kelp Crab

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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