Effect of hydration state on locomotor performance and water searching behavior of the terrestrial lungless salamander Bolitoglossa ramosi

Abstract

Bolitoglossa ramosi is a terrestrial plethodontid salamander particularly active during cloudy nights with high relative humidity in the environment. In this work, we tested the hypotheses that: (1) the hydration state of B. ramosi directly affects its locomotor performance; (2) dehydrated salamanders spend less time to find a water source than hydrated salamanders and (3) dehydrated salamanders find a water source in fewer attempts than hydrated individuals. To evaluate these hypotheses, salamanders at different levels of body hydration were used for an experiment of maximum locomotor performance, and a behavioral assessment test for searching a water source that was randomly located in one of the eight arms of a labyrinth. We found that salamanders hydrated at 95% had a greater locomotor performance (speed) than those hydrated at 85% and 75%. On the other hand, salamanders hydrated at 75% found the water source faster than those hydrated at 95%, although there was not a significant difference between these two groups of salamanders tested in the number of arms visited to find the water source. According to our results, we propose that dehydration in salamanders could be a causal factor for the inactivity of these animals during low levels of environmental humidity, and can also motivate a faster response to find a water source. In addition, we postulate that B. ramosi seems to use a random searching behavior to locate a water source as both hydrated and dehydrated salamanders find it after several attempts.