Fish-eating anemone

Urticina piscivora is a large anemone, growing to a maximum height of around 20 cm (8 in) and 10 cm (4 in) in diameter. The column is bright red in colour. The acontia is absent, but it has tubercles. These are not white and are arranged in circumferential rows. Normally they do not accumulate debris such as shells and sand. This anemone is made up of three layers of cells called the epidermis, the mesoglea and the gastrodermis. The epidermis forms the outermost layer, while the mesoglea is situated between the other two layers. The innermost layer, the gastrodermis also referred to as the gastrovascular cavity functions as the gut of the anemone.  The gut of the fish-eating anemone is divided into compartments by sheets of tissue called “septa”. These sheets of tissue develop into tentacles on the surface of the anemone.The tentacles of many species of anemones are found in multiples of six. Unlike other anemone the fish-eating anemone does not possess an acontia, which is  thread-like tissue made up of stinging cells that function as a defense mechanism to protect against predators. However this particular anemone does possess tubercles. This species may be confused with Urticina crassicornis. Although they may both have a red column, the tentacles of U. crassicornis normally have transverse bands, and olive green blotches are commonly found on the column.