ELECTRORECEPTION AND THE FEEDING-BEHAVIOR OF PLATYPUS (ORNITHORHYNCHUS-ANATINUS, MONOTREMATA, MAMMALIA)

It has previously been shown that platypus are sensitive to small elec trical fields. It was predicted that platypus use their electrosensiti vity to locate the source of foodstuffs on the bottom of the freshwate r river systems in which they live, because the platypus are nocturnal , and close their eyes, ears and nostrils while underwater. In this pa per we demonstrate for the first time that platypus are indeed sensiti ve to electrical waveforms that imitate the electromyogenic potential' s of fleeing prey, and following stimulation show interest in area sur rounding the electrodes. We also show that platypus respond with a ref lex after stimulation with a square wave, and show that this reflex is directionally tuned to the origin of the electrical pulse, with a pre ferential sensitivity axis 40 times more sensitive than non-preferred axes. The strong directional sensitivity explains previous discrepanci es in the lowest threshold for platypus electroreception, which we fin d to be 50 mu V cm(-1). Platypus are also sensitive to galvanic fields . We present the data in the light of standardized feeding strategies of the platypus, and discuss the integration of the findings into thes e feeding strategies. We surrounded our platypus enclosure with a Fara day cage, thereby eliminating excess electrical noise, a suggested new addition to the husbandry regime of platypus.