Toxic foraminifera: Innocent until proven guilty

Reticulopods of benthic and planktic foraminifera have been periodically reported to possess the ability to narcotize, paralyze or even kill larger prey organisms by means of toxins. This paper critically examines the historical development of the idea of toxicity in foraminifera and provides new observational data on prey capture in the benthic species Glabratella ornatissima. Data presently available provide only minimal evidence for the presence of toxins in foraminifera. Most available evidence suggests that foraminiferal prey capture is in large part mediated by molecular cell-surface receptors (e.g. carbohydrates, glycoproteins) present in the extracellular matrix of adhesive pseudopodia. A survey of available data indicates that the majority of experimentally studied foraminifera exhibit the capability to effectively capture motile prey organisms, including in at least some cases organisms that exceed the predator body size. This suggests that the reticulopodial networks of many foraminiferal species may function as effective traps for a variety of motile organisms and that carnivory in foraminifera may be more widespread than previously assumed.