[3] This sea anemone lives at bathyal depths in the North Atlantic Ocean and has a symbiotic relationship with a gastropod mollusc.

The six pairs of mesenteries are complete, in that their sheetlike membranes join the gastrodermis of the body wall with that of the pharynx, and are sterile, in that they do not bear gonads.

[5] Gastropods with one or two sea anemone on their shells were found to have greater feeding success and more varied stomach contents than those with either no epibionts, or with three or more.

The sea anemone gained advantage from being an epibiont as it is itself sometimes attacked by the starfish Crossaster papposus, but was able to escape from this predator when attached to a living gastropod mollusc.

[5] Despite living at bathyal depths where no light penetrates, A. parasitica is one of a number of deep sea species that show synchronisation in the release of eggs and sperm to the phases of the moon.