Sea Urchins and Sand Dollars

Below are examples of sea urchins and sand dollars I’ve run across and photographed on Pacific Northwest shores. It’s a scant list. Nevertheless, my organization follows Lamb and Hanby (2005). The common names are my choices; unless noted, the photos are from northern Oregon. Experts cover these urchins and sand dollars and more in the guides and online resources at the bottom of this page.


Strongylocentrotus purpuratus, purple sea urchin

Sea urchin exposed by low tide, resting in a shallow rock burrow.
Found or made a hollow | Central Oregon
A collector of seaweed | Central Oregon
Abundant sea urchins in a tidepool. Above, exposed gooseneck barnacles.
This pool has what it takes | Central Oregon
A sea urchin test rests on the sand among drifted crab remains and live giant green anemones.
Sometimes you’ll find an empty test (at the green arrow) | Central Oregon
Closeup on six sea urchins in a shallow crystal clear pool.
They’re lovely up close in a clear tidepool | Central Oregon
***

Dendraster excentricus, eccentric sand dollar
On the open coast, it’s most common to find bleached shell fragments. Sand dollar beds are mostly subtidal, but some bays have beds that are more or less accessible at low tide.

Late afternoon light on a bleached complete shell
Dendraster excentricus, eccentric sand dollar
Whole bleached shell partially buried in clean beach sand
Everybody’s after that perfect sand dollar shell
An upside down bleach whole shell on clean beach sand
The bottom or underside shows the mouth opening
***

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. 2019. The New Beachcomber’s Guide to the Pacific Northwest. Harbour Publishing.


Online Resources

Biodiversity of the Central Coast’s Echinoderms page. Accessed May 7, 2023.

Common Sea Life of Southeastern Alaska: A field guide by Aaron Baldwin & Paul Norwood. Accessed May 7, 2023.

Friends of Netarts Bay WEBS Echinoderms page. Accessed May 7, 2023.


Cowles, D. (2005). Strongylocentrotus purpuratus (Stimpson, 1857). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed May 7, 2023.

Cowles, D. (2006). Dendraster excentricus (Eschscholtz, 1831). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed May 7, 2023.


I updated this page on May 7, 2023