May 15 saw a pretty good low tide on theoutershores, about 2 feet below mean lower low water, so I was able to explore some surf-swept rocks that jut out of the sand. These islands in the sand are usually inaccessible, so the low tide offered me an opportunity to see what lives on them.

Rocks and rocky headlands jutting out of the sand.
Rocks and rocky headlands jutting out of the sand.

The rock above is covered with surfgrass, Phyllospadix scouleri, barnacles and various kinds of encrusting and branched coralline red algae.

Idotea, possibly I. wosnesenskii.
Idotea, possibly I. wosnesenskii.

Running my fingers through the surfgrass I encountered this attractive crustacean, the isodpod, Idotea. There are a few species of Idotea, and, for a non expert, some of them can be hard to tell apart. I’m pretty sure this one is I. wosnesenskii

Idotea, taken from the stomach of a retail surfperch, A. rhodoterus.
Idotea, taken from the stomach of a retail surfperch, A. rhodoterus.

I was first introduced to Idotea two years ago when I found one in the stomach of a redtail surfperch. I think surfperch love to eat them when they can because I’ve seen many in surfperch stomachs since then. I have never seen a live one before and have always wondered where they caught them. That riddle is now partly solved.

If you are interested in other surfperch food items I have discovered, check out Dabbling with Crustacean Competition.

Acknowledgements

I’m grateful to Allison Barner for weighing in on the identity of the Idotea fearured in this post (but if I made the wrong call, it’s on me). Sometimes you’ll see her tweets about the rocky intertidal on the sidebar of my homepage.

References

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.

Light, S. F., 2007. The Light & Smith Manual: Intertidal Invertebrates from Central California to Oregon. 4th ed., edited by J. T. Carlton. University of California Press.

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

3 thoughts

  1. I was introduced to Idotea in Baja (or something pretty similar) when I fell asleep on a beach on an island in the Sea of Cortez covered in them and with several up inside my bathing suit!

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