Aggregating anemones, Anthopleura elegantissima, don’t mind a little crowding. They seem to need it. You’ll find them packed column-to-column. They cloak tide pool rocks so densely you might be fooled into thinking you’re looking at bare rock. It’s not until you take that first squishy step that you discover your mistake.

Densely packed Anthopleura elegantissima, exposed at low tide
Exposed at low tide, you might mistake this dense colony of A. elegantissima for a bare rock surface

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 they 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 rocks. Rough can be explained their bumpy columns which accumulate seashell fragments. You’ll notice this in the images above. Elegant is a nod to their good looks and scientific epithet, elegantissima.

Aggregating anemones in a sand-filled tide pool
Aggregating anemones are are also called pink-tipped and sand anemones

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 wall below?

Colonies of aggregating anemones and a few giant greens exposed on a vertical rock wall at low tide.
Exposed vertical wall with colonies of A. elegantissima; large anemones are A. xanthogrammica

That’s some fun with common names- aggregating, pink-tipped, sandy, surf, rough, elegant, and clonal- A. elegantissima lives up to each. Which one do you favor?

References

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.

Web Resources

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.

Dense

4 thoughts

  1. I like Elegant Anemones. It’s the assonance. Thanks for sharing your sea creature knowledge – I always enjoy it.

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