Meeting Abstract
The ability of fully aquatic animals to overcome the water to land transition raises a fundamental question – how is movement facilitated on land? Body elongation has evolved repeatedly within aquatic vertebrates with some of the earliest tetrapods having more elongate forms. The repeated evolution of fishes with elongate bodies poses pivotal questions about how body shape affects life strategies and habitats and how body shape may enable fishes to cope with a dynamic environment. Here, we investigated the underlying axial diversity in fishes with eel-like body plans that are known to make terrestrial excursions to varying degrees. In addition to an elongate body, these fishes tend to have reduced or lost their pectoral fins, which results in movements that tend to be propelled exclusively by the body. We measured a set of external characteristics as well as traits that comprise the axial and appendicular skeleton for 30 species of fishes representing diverse ecological and evolutionary histories. For a subset of these fishes, we conducted locomotor trials on a wet pebble substrate to characterize variability in movement patterns to better understand the relationship between morphology and motion. Our preliminary data suggests that external characteristics varied more across elongate species than we previously anticipated but that dorsoventral flattening of the body versus a taller more laterally compressed body resulted in similar locomotor patterns. It has been previously posed that irrespective of how elongate a fish is, lateral undulation in the terrestrial environment may be characterized by anterior to posterior waves. Our preliminary work shows that this is the case even when examining species that have comparable lengths but different means of elongating the body and subtle differences in secondary axis reduction.
