Biology of Parasitic Heterotrophic Nanoflagellates: Parasitoids of Diatoms

Abstract

Heterotrophic nanofl agellates are important consumers of bacteria in all environments. Nowadays, some few exceptions are known, termed parasitic nanofl agellates ( PNF ), feeding on much larger prey in marine waters. They are feeding on planktonic and benthic diatoms. Since these fl agellates inevitably kill their host they are parasitoids rather than parasites despite the use of the term PNF. The name parasitic nanofl agellate refers to an ecological function rather than to taxonomic entities, since these organisms correspond to different taxonomic groups. It can be expected that the diversity of PNF is much greater than known so far, since reports of undescribed species can be found in the literature. Examples of different parasitoidic nanofl agellates are given here. Morphological features and taxonomic positions of these species, as well as their sophisticated modes of infection and food acquisition, will be described.