In the common sea-anemone, Actinia equina (which has already been quoted as a type of Anthozoan structure), the mesenteries are numerous and are arranged in cycles.
The most familiar Anthozoan is the common sea-anemone, Actinia equina, L., and it will serve, although it does not form a skeleton or corallum, as a good example of the structure of a typical Anthozoan polyp or zooid.
In Actinia and its allies, and most generally, though not invariably, in Anthozoa,the stomodaeum is not circular, but is compressed from side to side so as to be oval or slit-like in transverse section.
In common with all Coelenterate animals, the walls of the columnar body and also the tentacles and peristome of Actinia are composed of three layers of tissue.
The individual animal or zooid of Actinia equina has the form of a column fixed by one extremity, called the base, to a rock or other object, and bearing at the opposite extremity a crown of tentacles.
In Actinia equina the mesogloea consists of fine fibres imbedded in a homogeneous matrix, and between the fibres are minute branched or spindle-shaped cells.
In Actinia equina the Edwardsia stage is arrived at somewhat differently.
The first twelve mesenteries are disposed in couples, and do not differ from those of Actinia except in size.