Reffling: A Novel Locomotor Behavior Used by Neotropical Armored Catfishes (Loricariidae) in Terrestrial Environments

Abstract

Neotropical suckermouth armored catfishes (Loricariidae) are known to exhibit terrestrial behaviors, but these have been poorly described. The goals of this study are to describe (1) the terrestrial locomotion of loricariid catfishes, (2) how their unique morphology may affect terrestrial movements, and (3) how behavior, performance, and kinematics relate to species and endurance. The terrestrial locomotion of four loricariid species (three species of Pterygoplichthys and one species of Hypostomus) was recorded using high-speed cameras. Videos were digitized in MATLAB and ImageJ to compare performance and kinematics between species and over time. Morphology was described using micro-computed tomography scans and dissections. Loricariid catfishes use a novel, highly asymmetric form of axial-appendage-based terrestrial locomotion involving their mouth, pectoral fins, pelvic fins, posterior axial body, and tail. As this behavior is so unlike any other described locomotor behavior, we have created a new word to describe it: reffling. These species have numerous unique morphological traits that may greatly reduce body and fin flexibility. Because loricariids are so inflexible, they may be constrained into reffling as their only means of terrestrial locomotion, but their stiffness may improve force transmission, allowing them to be among the fastest fishes on land. Overall, all four species examined had very similar terrestrial kinematics and performance. Their performance generally declined over time, but different species had different endurance levels. Because many loricariid species are invasive throughout the world, it is important to consider their capacity to disperse into new bodies of water overland in management plans and risk assessments.