Aggregating anemones, Anthopleura elegantissima, are okay with crowding. You’ll find them packed column-to-column so densely you might be fooled into thinking you’re looking at a bare rock. You discover your mistake only when you take that first squishy step.
Anthopleura elegantissima is genuinely an aggregating anemone. It’s easy to understand how it came by its common name, but aggregating is only one of its common names. Lamb and Hanby (2005) call it pink-tipped but also list sandy, surf, rough, elegant, and clonal. Each name has a reason. The photo below explains pink-tipped and sandy (they flourish on sand-scoured rocks and sandy tide pools; I wrote about this affinity in Aggregating Anemones Handle the Sand). Surf refers to their preference for surf-swept settings. Rough can be explained by their bumpy columns, which accumulate seashell fragments. You’ll notice this in the images above. Finally, elegant is a nod to their good looks and scientific epithet, elegantissima.
That leaves clonal. The individuals in each colony are genetically identical, the product of asexual reproduction. Where A. elegantissima is abundant, the rocks are a mosaic of colonies delineated by narrow uninhabited boundaries. Can you detect some clonal boundaries on the rock face below?
That’s some fun with common names—aggregating, pink-tipped, sandy, surf, rough, elegant, and clonal—A. elegantissima lives up to each. So which one do you favor?
Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.
Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.
Pacific Rocky Intertidal Monitoring: Trends and Synthesis page on Anthopleura
PS- If you like sea anemones I just opened up a page with photos and a few words about common intertidal sea anemones from the Northern Oregon coast.
I updated this page on January 23, 2023