page_title: Aggregating anemone
section_title: Agonism between colonies
hierarchical_section_title: Aggregating anemone / Natural history / Agonism between colonies
caption_attribution_description: English: Sea Anemones,Anthopleura elegantissima are engaged in a clone war for the w:territory. The white tentacles are fighting tentacles. They are called acrorhagi. The acrorhagi contain concentration of stinging cells. After war ends one of Sea Anemone, should move. Sea Anemones look as plants, but they are animals and they are predators. The image was taken in Northern California w:Tide pools
context_page_description: 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. The aggregating anemone has become a model organism for the study of temperate cnidarian-algal symbioses.
context_section_description: The aggregating anemone is agonistic toward other individuals with different genetic disposition. When one colony of genetically identical polyps encounters a different genetic colony, the two will wage territorial battles. Aggregating anemones have specialized  tentacles called acrorhagi that are used solely to deter other colonies from encroaching on their space. When a polyp makes physical contact with a non-clonemate, it extends the acrorhagi to attack the competing anemone with stinging cells called nematocytes.  Acrorhagi of the attacking anemone leave behind a 'peel' of the ectoderm and nematocysts that causes tissue necrosis in the receiving animals.
  A study of two colonies on a boulder removed from the shore and brought into a laboratory revealed that hostilities between neighboring colonies follow the tides.  As water rushed into the tank, warrior polyps inflated their acrorhagi, tripled their body length and began reaching into an empty swath of rock between the colonies.  Occasionally, a polyp from one of the colonies would move into the spatial zone between the two colonies, acting as a scout, and would be attacked by the warrior polyps of the other clone. If the scout polyp received enough stings, it would be attacked by its clonemates upon return to its own colony. The return of an attacked scout to the clone with acrorhagial peel may serve to communicate the presence and identity of neighboring clones to the interior of the colony.
caption: Territorial battle between anemones
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