Aggregating Anemone

At a glance

Aggregating Anemone (Anthopleura elegantissima) is a cnidarian present across the CatchRules coverage area but without species-specific bag, size, or season rules tracked in our regulatory dataset.

Confirmed by 26,982 research-grade iNaturalist observations, with California, British Columbia, and Washington the top jurisdictions by observation count.

Notable details

• Reproduces asexually by splitting in two, forming dense clonal mats on rocky shores.
• Adjacent clonal groups wage 'clone wars,' battling rivals using specialized stinging tentacles called acrorhagi.
• Hosts symbiotic algae inside its cells, giving sun-exposed individuals a vivid green color.
• Can survive hours out of water during low tide by retracting its tentacles inward.
• One of the most abundant intertidal invertebrates along the entire Pacific Coast of North America.

Where Aggregating Anemone are seen

• California11,872 iNat obs
• British Columbia7,098 iNat obs
• Washington5,634 iNat obs
• Oregon2,373 iNat obs
• Alaska5 iNat obs

Background

Anthopleura elegantissima, also known as the aggregating anemone or clonal anemone, is the most abundant species of sea anemone found on rocky, tide swept shores along the Pacific coast of North America. This cnidarian hosts endosymbiotic algae called zooxanthellae that contribute substantially to primary productivity in the intertidal zone. A. elegantissima has become a model organism for the…

Background excerpt adapted from Wikipedia's Aggregating Anemone article (CC BY-SA). Visit Wikipedia for the full entry.