Phagotrophy by a plastidic haptophyte, Prymnesium patelliferum

Observations and photographs of the previously unsuspected ingestion capacity of the phytoflagellate Prymnesiurn patelliferurn are presented. P. patelliferurn took up prey cells of different sizes by an elongated, U-shaped pseudopodium formed at the posterior part of the cells. While feeding, aggregates of several P. patelliferurn cells were formed in which their pseudopodia come in close contact. Motile prey cells were immobilised or probably killed before ingestion, but not all protistan species of ingestible size were immobilised or attacked. It is suggested that P. patelliferurn may secrete a toxin that serves as a killing agent for prey organisms.