Hairy Hermit Crab

Pagurus hirsutiusculus

Hairy Hermit Crab

Pagurus hirsutiusculus

Other Common Names
Pacific Hairy Hermit Crab

Sandy Coast, Rocky Coast

Other Common Names

Pacific Hairy Hermit Crab

At the Aquarium

Sandy Coast, Rocky Coast

Appearance

The hairy hermit crab grows to 0.8” and is commonly found in a shell that seems to barely fit! You’ll know it is a hairy hermit crab if it has banded brownish and white antennae, and white bands that encircle the outer joints of its second and third walking legs. Each walking leg usually has 1 or 2 blue dots and its body has numerous small hairs. The right claw is larger than the left and is mainly used in defense. The smaller left claw is used for eating and selecting new shells.

Habitat

Intertidal zone to depths of ~360’ (110 m). Rocky areas, tidepools, silty areas.

Diet

Mainly detritus, seaweeds

Life History

A hairy hermit crab male deposits sperm near the female’s abdomen. She stores it until she lays her eggs, then fertilizes them. She begins brooding in late fall, carrying the eggs inside the shell, on the left side, with larvae hatching around February. Most females carry 5 broods a year through the spring and summer months. A single brood can have up to 660 eggs, with larger females laying more eggs.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

As a detritivore, these crabs cycle nutrients from dead plants and animals back into the ecosystem. They also serve as food for their predators, which includes sculpins and other crabs.

Alaska to California. Also found in Japan and Siberia.

You are likely to find hairy hermit crabs in tidepools–check under rocks or within seaweeds!

Hermit crabs do not make their shells but take those of snails that have died. Some favorite snail shells of the hairy hermit crab are the frilled dogwinkle (Nucella lamellosa), dire whelk (Searlesia dira), periwinkles (Littorina genus), and purple olive shells (Callianax biplicata). In selecting a shell, a hairy hermit crab will examine it using its left claw, as the hairs on this claw are able to detect calcium. Many hairy hermit crabs will carry shells that they can’t completely withdraw into. If need be, they will drop their shell and use speed to outrun a predator.

Citations & Other Resources

Arthropod Page of Netarts Bay Today: https://www.netartsbaytoday.org/Arthropods_Text.html#LayoutGrid36
Biodiversity of the Central Coast website: https://www.centralcoastbiodiversity.org/hairy-hermit-crab-bull-pagurus-hirsutiusculus.html
Evergreen College website: https://archives.evergreen.edu/webpages/curricular/2007-2008/ize/web/pagurus_hirsutiusculus.html
Invertebrates of the Salish Sea website: https://inverts.wallawalla.edu/Arthropoda/Crustacea/Malacostraca/Eumalacostraca/Eucarida/Decapoda/Anomura/Family_Paguridae/Pagurus_hirsutiusculus.html
Scholar’s bank website: https://scholarsbank.uoregon.edu/xmlui/bitstream/handle/1794/12728/P_hirsutiusculus_2015_final.pdf?sequence=3&isAllowed=y

Hairy Hermit Crab

Hairy Hermit Crab

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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