Meeting Abstract
P2.40 Saturday, Jan. 5 Tradeoffs in anguilliform locomotion over complex substrates in Stichaeid fishes DIAL, T.R.*; SUMMERS, A.P.; BRAINERD, E.L.; Brown University; University of Washington; Brown University terry_dial@brown.edu
Elongate body forms have repeatedly evolved throughout ectothermic vertebrates. Anguilliform locomotion works by propagating undulatory waves down the length of an elongate body offering proficient aquatic locomotion but also permitting various degrees of terrestrial locomotor competence. Terrestrial movement involves body waves creating contact points to push against the substrate in order to propel the animal forward or downward (i.e., to bury). Tradeoffs may exist among alternate body forms that utilize aquatic, intertidal, over-ground terrestrial, and digging locomotion. This study compared locomotor performance between three species of Pricklebacks (Teleosei: Stichaeidae), a group of elongate fishes that span subtidal-intertidal habitats. We measured whole body velocity, amplitude, frequency, wavelength and Froude efficiency (ratio of forward speed to wave speed) in Xiphister atropurpureus (intertidal), Lumpenus sagitta (subtidal) and Anoplarchus purpurescens (intertidal and subtidal), over five substrates (water, plexi glass, sand, pebbles and rocks). Substrates elicited differential performance: all three species were significantly slower when moving over land, but not all suffer a reduction in efficiency. X. atropurpureus was found to move as efficiently on land as in water (Fr=0.7, P<0.05). L. sagitta was only efficient in water, (Fr=0.75) whereas A. purpurescens was efficient in water and over rocks (Fr=0.5), but not on the other substrates. This study suggests there is a species-specific gradient of performance as animals transition from water to land consistent with their preferred habitat. Within the Stichaeidae, A. purpurescens illustrates the predicted tradeoff of possessing an intermediate body form, and corresponding locomotor performance, between X. atropurpureus (proficient on land) and L. sagitta (proficient in water).
