The Kinematics of Salamander Underwater Walking on Smooth and Rough Substrate

The transition from aquatic to terrestrial locomotion was a landmark event in the evolutionary history of vertebrates. In order to better understand how early tetrapods were able to transition to land, salamanders have proven to be a useful animal model. With current research focusing heavily on the anatomy, physiology, and kinematics defining salamander terrestrial walking capabilities, this experiment was designed to extract information about the kinematics of salamander walking underwater. Underwater walking of salamanders was analyzed on smooth and rough substrates to provide more insight into the early vertebrate water-to-land transition. Average salamander stride duration, time in stance phase, time in swing phase, duty factor, stride length, stride velocity, minimum foot velocity phase location, maximum foot velocity phase location, and foot slip distance were compared between salamander underwater walking on smooth and rough substrate conditions. It was found that stride duration, stance duration, and swing duration were significantly greater when salamanders walked underwater on rough substrate. Thus, the kinematics of underwater salamander walking differ to some degree when the salamander walks on smooth or rough substrate