SOME RELATED ASPECTS OF PLATYPUS ELECTRORECEPTION - TEMPORAL INTEGRATION BEHAVIOR, ELECTRORECEPTIVE THRESHOLDS AND DIRECTIONALITY OF THE BILL ACTING AS AN ANTENNA

This paper focuses on how the electric field from the prey of the plat ypus is detected with respect to the questions of threshold determinat ion and how the platypus might localize its prey A new behaviour in re sponse to electrical stimuli below the thresholds previously reported is presented. The platypus shows a voluntary exploratory behaviour tha t results from a temporal integration of a number of consecutive stimu lus pulses. A theoretical analysis is given, which includes the thresh old dependence on the number of receptors and temporal integration of consecutive stimuli pulses: the close relationships between electrical field decay across the bill, electroreceptive thresholds and directio nality of the platypus bill acting as an antenna. It is shown that a l obe shape, similar to that which has been measured, carl be obtained b y combining responses in a specific way from receptors sensing the ele ctric field decay across the bill. Two possible methods for such combi nations are discussed and analysed with respect to measurements and ob served behaviour of the platypus. A number of factors are described wh ich need to be considered when electroreceptive thresholds are to be d etermined. It is shown that some information about the distance to the source is theoretically available from the pattern of field decay acr oss the platypus's bill. The paper includes a comparative analysis of radar target tracking and platypus prey localization.