Meeting Abstract
Mummichogs (Fundulus heteroclitus) are intertidal fish that exhibit amphibious traits, such as the ability to breathe air and locomote on land. Our goals were to characterize the terrestrial jumping behaviors of F. heteroclitus and determine their method of navigation towards water in an unfamiliar terrestrial environment. We used high-speed video (210 fps) to record behavior during stranding trials. Similar to observations in other Cyprinodontiformes, F. heteroclitus primarily uses a tail-flip jump during terrestrial locomotion. Additionally, we found that F. heteroclitus will prop themselves upright between each jump on their caudal and pectoral fins, although sometimes for only a fraction of a second. They then rotate their bodies to point the tail in the direction of the water, fall onto their lateral aspect, and then leap into a caudally-directed ballistic flight path. During experiments to determine the sensory stimulus used to locate a body of water, F. heteroclitus were placed on a platform with four sides, with one side adjacent to a sea table. In ambient light, F. heteroclitus move towards the sea table more often than towards the other edges of the table (χ2 = 20.62, p = 0.0001). Under low-light conditions, F. heteroclitus are less successful at reaching the sea table (z = 2.42, p = 0.0078). When the surface of the water is replaced with reflective foil, F. heteroclitus will move towards it as if it were a body of water (χ2 = 11.92, p = 0.0077). These results suggest that F. heteroclitus primarily uses visual cues, specifically the reflection of light, to orient towards water. Uprighting behaviors during terrestrial locomotor bouts may provide an opportunity for fish to receive visual information that allows them to safely return to the water.
