PHAGOTROPHY BY A PLASTIDIC HAPTOPHYTE, PRYMNESIUM-PATELLIFERUM

Observations and photographs of the previously unsuspected ingestion c apacity of the phytoflagellate Prymnesium patelliferum are presented. P. patelliferum took up prey cells of different sizes by an elongated, U-shaped pseudopodium formed at the posterior part of the cells. Whil e feeding, aggregates of several P. patelliferum 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 sugges ted that P. patelliferum may secrete a toxin that serves as a killing agent for prey organisms.