Noriko Okamoto

A non-photosynthetic dinoflagellate, Blastdinium sp. (a white mass), is found in the gut of a copepod caught in a plankton tow. The tiny cell swallowed by the animal grows to form a large multicellular trophocyte as shown here; upon maturation, hundreds of the new-born sporocytes will be released eventually from the animal's rear end.