Sensory orientation in Notophthalmus v. viridescens (Amphibia: Salamandridae)

Abstract

Adult red-spotted newts, Notophthalmus v. viridescens, were collected from an aquatic habitat and released on land in an arena 20 m from the shore of their home pond. Freshly captured, untreated newts exhibited significant orientation toward the pond. Positive orientation was also observed when solar cues and pondside landmarks were hidden and when animals were released at night. Pondward orientation persisted in eyeless newts and in newts with the pineal organ covered. Eyeless newts with covered pineals failed to orient toward the pond, although they did exhibit directional orientation. Anosmic newts exhibited random orientation. All sham-operated control groups oriented in the direction of the pond.Olfaction is implicated as the sensory mechanism most essential to home pond orientation. Photoreception is of secondary importance, apparently acting in conjunction with olfaction to refine the directional accuracy.