Phototaxis in Anurans: Relation between Intensity and Spectral Preferences

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Abstract
Hypotheses formulated in previous work on anuran phototaxis were tested by examining 6 previously unstudied species and providing more complete data on 2 previously studied species [Rana aurora, Kassina senegalensis, Kalorela pulchra, Bufo hemiophrys, B. microscaphus, Eleutherodactylus martinicensis, E. nubicola, E. orcutti]. It is hypothesized that the fundamental adaptive difference among species is the set-point of their optimum ambient illumination (O.A.I.)-the preferred modal intensity in phototactic tests with white light. When intensities of spectrally dominant light are below the species'' O.A.I. animals have a blue color-preference, and when intensities are above the O.A.I. animals choose the ends of the spectrum (violet and red) in a preference that cannot be proven to involve true color vision. The new data presented in this study are totally consistent with the hypotheses, which provide a discrete framework for further study of the adaptiveness of phototactic behavior under field conditions.