Motile chemosensory behaviour of phagotrophic protists: Mechanisms for andefficiency in congregating at food patches

Phagotrophic protists are capable of congregating at point sources of food within a few minutes, from distances of up to several cm in the case of cil iates, or several mm in the case of microflagellates. This is exemplified b y four ciliate species and a heterotrophic flagellate. Congregation is acco mplished by the combined effect of more than one type of chemosensory motil e behaviour including "kinetic responses", "temporal-gradient sensing", and "helical klinotaxis". The results are discussed in terms of microscale pat chiness in nature.