Isopods

Below are examples of isopods you might find on Oregon’s exposed rocky shores or beaches. The photos on this page are from northern Oregon unless noted in the caption. My organization follows Lamb and Hanby (2005). Common names are my choice. I refer to WoRMS for scientific names, and I learn a ton by browsing the natural history riches in Kozloff (1993). Biodiversity of the Central Coast’s Crustaceans page is full of great information on Pacific Northwest isopods. The books, field guides, and identification resources listed at the bottom of the page also cover these isopods and many more.

Pentidotea wosnesenskii

  • Pentidotea wosnesenskii, disturbed here, I found it hidden deep in the surfgrass
  • Pentidotea wosnesenskii blends in among Schizymenia blades
  • Low tide exposed this stack of four P. wosnesenskii (one not visible in this view)

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Idotea sp.– I’ve only come across this slender isopod once. I’m not sure what it is, but there aren’t a lot of slender intertidal isopods with a similar-shaped prototelson. Idotea ochotensis is in the running for sure, and maybe Idotea fewkesi; there are probably other candidates too. I noticed it at the bottom of a sand-filled tidepool below a single mussel-covered boulder. The photographs below are the same individual, first in a white finger bowl, then on clear glass. If you know what this slender beauty is, please drop me a line.

  • A mystery from the low intertidal
  • Just a bit over 3 cm long

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References

Gotshall, D. W. 2005. Guide to Marine Invertebrates, Alaska to Baja California 2nd Edition (Revised). Shoreline Press.

Harbo, R. M. 2011. Whelks to Whales: Coastal Marine Life of the Pacific Northwest. 2nd ed. Harbour Publishing Co.

Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.

Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.

Sept. J. D. 2009. The Beachcomber’s Guide to Seashore Life in the Pacific Northwest. Revised ed. Harbour Publishing.


Online Resources

Biodiversity of the Central Coast’s Crustaceans page is full of great information on Pacific Northwest isopods.

Pacific Northwest Shell Club’s Crustaceans page.

Friends of Netarts Bay’s Crustaceans page.

iNaturalist’s Idotea page.


This page was updated on August 9, 2020