Mechanisms underlying chemical interactions between predatory planktonic protists and their prey

Predatory protists use chemical recognition to increase feeding efficiency by responding to point sources of prey chemoattractants and through adhering to the cell surface of their prey. In response, their prey possess a multitude of chemical-based antipredator strategies. Given that these chemical interactions play a key role in driving aquatic food webs, we emphasize the need for a better knowledge of the associated underlying mechanisms. As the mechanisms underpinning such chemical interactions have been intensively researched for certain non-planktonic model protists, we highlight that studies on these model organisms can help elucidate the mechanisms involved in planktonic predator?prey interactions. A related future challenge will be to interpret the evolutionary and ecological consequences of these chemical interactions within planktonic communities, and here this will be discussed in relation to coevolutionary arms races and costs.