Use of electroreception during foraging by the Australian lungfish

A diverse range of animals, including elasmobranchs and nonteleost fish, us e passive electroreception to locate hidden prey. The Australian lungfish, Neoceratodus forsteri (Krefft 1870), has ampullary organs analogous in form to the. electroreceptors of other nonteleost fish. Afferents from these am pullae project to regions in the brain that are known to process electrosen sory information in other species, suggesting that N. forsteri possesses an electric sense that may be used during prey location. To explore this hypo thesis directly, we first characterized food-locating behaviour in N. forst eri and then conducted an experiment designed to quantify the effects of ma nipulating electrical and olfactory stimuli from live prey. A small crayfis h, Cherax destructor, was housed in a specially constructed chamber hidden beneath the substrate, which prevented emission of chemical, mechanical and visual cues, but allowed transmission of bioelectric fields. Control treat ments included presentation of electrically shielded prey, a dead crayfish and an empty chamber. In some treatments, a competing olfactory signal was presented simultaneously at the other end of the test tank to assess the re lative salience of this sensory modality. The lungfish responded to the cra yfish in the unshielded chamber with accurate and sustained feeding movemen ts, even with a competing olfactory signal. By contrast, the abolition of e lectrical cues in the three control treatments reduced the accuracy and fre quency of feeding movements in the vicinity of the target chamber. These re sults show that, N. forsteri is capable of perceiving the weak electric fie lds surrounding living animals, and Suggest that it uses this information w hen foraging to locate prey hidden from view. (C) 1999 The Association for the Study of Animal Behaviour.