Aggregating anemone

Anthopleura elegantissima

''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 study of temperate cnidarian-algal symbioses.
Pink-Tipped Anemone  Aggregating anemone,Anthopleura elegantissima,Canada,Geotagged,Summer

Appearance

The polyps of ''Anthopleura elegantissima'' reach up to eight cm across the oral disk with approximately 100 tentacles in three or four rows around the margins of the oral disk. Most are olive to bright green with tentacles tipped in pink. Individuals that live in microhabitats that are deficient in photosynthetically active radiation , such as under docks or in caves, lack symbionts and are pale yellow to white in color.

Predators

The few known predators of ''Anthopleura elegantissima'' include the nudibranch ''Aeolidia papillosa'', leather star ''Dermasterias imbricata'' and mosshead sculpin ''Clinocottus globiceps''.

Evolution

This species of anemone is capable of reproducing both sexually and asexually. As adults, ''A. elegantissima'' release gametes into the water that join to form genetically unique individuals that settle on intertidal rock. This genetically distinct individual can then proliferate through binary fission. Some argue that this is not true reproduction but actually a form of growth. Fission is often prompted in the autumn by a decrease in the abundance of food and follows sexual spawning in summer. Over time, a single individual can generate a large colony of genetically identical polyps. Because of its ability to grow in this manner, the genetic entity of a colony is potentially immortal on an ecological time scale.

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Taxonomy
KingdomAnimalia
DivisionCnidaria
ClassAnthozoa
OrderActiniaria
FamilyActiniidae
GenusAnthopleura
SpeciesA. elegantissima
Photographed in
Canada