EVALUATION OF THE HATCHING TRIGGER AND LARVAL ECOLOGY OF THE SALAMANDER AMPHIUMA MEANS

Abstract

I investigated the early life history of the salamander Amphiuma means. Although adult A. means are entirely aquatic, eggs are often found above water levels in areas from which water has receded. A series of experiments was performed using three egg clutches of A. means collected from organic sediment at the bottom of a dried lake in northern Florida. The first experiment demonstrated that eggs of A. means hatch in response to inundation with water, and aquatic larvae completely resorbed their gills in about 2 wk. Eggs that hatched at later dates produced larger hatchlings in all three clutches and larger juveniles at metamorphosis in two clutches. A second experiment indicated that hatchlings can survive, on average, over 125 d without feeding by using resources from their yolk reserves. The third experiment showed that eggs are capable of surviving an average of 110 d (SD = 47.2 d) on moist substrate without hatching. Some eggs hatched onto the substrate without inundation, and resulting hatchlings could survive on this substrate without inundation for an average of 21 d (SD = 26.1 d). Five eggs produced hatchlings without gills during this experiment, suggesting that this species may bypass the larval period completely if eggs are not inundated. My experiments suggest that the eggs of A. means may be specialized for development in terrestrial nest chambers. Information on development and larval ecology of A. means from my study can be applied to future evaluations of the evolutionary relationships of salamander families.