Meeting Abstract
Although most fishes are considered to be fully aquatic, many are able to move effectively on land using a behavior called a tail-flip jump. The tail-flip jump is also used by amphibious fishes that have modified their respiratory and integumentary systems for prolonged (days to months) terrestrial excursions. We filmed four species of Cyprinodontiform fishes performing the tail-flip jump in high speed (600Hz): three aquatic species (Jordanella floridae, Gambusia affinis, and Poecilia mexicana), and one amphibious species, Kryptolebias marmoratus. We predicted that amphibious Kryptolebias would produce longer jumps than the three aquatic species studied here, and that jump performance would not decline as Kryptolebias individuals grow larger. We also quantified the scaling relationships between body size and jump performance in both aquatic and amphibious species. As aquatic species become larger, tail-flip jump distance declines (mass scaling coefficient, m = -.22). In contrast, as amphibious species become larger, tail-flip jump distance increases (m = +.41). As Kryptolebias indviduals become larger, their acceleration during the preparatory phase of the tail-flip jump increases (m = +.38) and their contact time remains relatively constant (m = ~0), which allows them to reach greater take off velocities at larger body sizes. Because Kryptolebias has no dramatic morphological specializations for life in the terrestrial realm, we hypothesize that fish retain jump performance at relatively large sizes through evolutionary changes to axial muscle distribution and/or changes in axial muscle fiber type.
