Erythropsidinium

Erythropsidinium (formerly Erythropsis) is a genus of dinoflagellates (a type of unicellular eukaryote) of the family Warnowiaceae.

==Characteristics== Erythropsidinium cells are a relatively large by dinoflagellate standards (50-120μm in longest dimension) and possess two flagella and two unusual organelles, the ocelloid and the piston. The ocelloid is light-responsive structure organized similarly to a multicellular organism's eye, considered a synapomorphic character for the Warnowiaceae; cells typically contain one ocelloid but occasional examples have been reported of cells containing two, without other indications of ongoing cell division. The piston is a long contractile structure protruding from the cell body, which is highly variable in length and morphology, and may contain prominent nodules along its length. As with the ocelloid, most cells possess a single piston, but in some cases specimens have been observed with two pistons on the same cell. The piston is capable of repetitive and dramatic contractile motion; its function is not clear, but roles in locomotion, prey capture, and defense have been suggested.