Meeting Abstract
57.5 Tuesday, Jan. 5 Lateral line sensing depends on the volume of the swim bladder in larval fish STEWART, W.J.*; BREUER, K.S.; MCHENRY, M.J.; Univ. of California, Irvine; Brown University; Univ. of California, Irvine wstewart@uci.edu
The ability to detect the water flow generated by a predator could be essential to the survival of a larval fish. However, it is not well understood what flow stimuli a larval fish detects before triggering an escape response. Mathematical modeling suggests that the density of a larva’s body is a major factor in determining the flow of water relative to the body that may be detected by the lateral line system. The goal of the present study was to evaluate how this relative flow varies in the early development of larval zebrafish (Danio rerio), when the density of the body changes as the swim bladder inflates. We developed a novel approach for measuring the tissue density of anesthetized larvae (3-6 days post fertilization (dpf)) from measurements of terminal velocity in solutions of varying density. Over the course of growth, tissue density decreased from 1.06 g mL-1 to 1.0045 g mL-1. We considered the implications of these changes on relative flow using an analytical model of a larva in the pressure field generated by a suction-feeding predator. Our results suggest that the flow velocity generated by a predator is substantially reduced (>98%) with respect to the frame of reference of the larva’s body (the larva moves with the surrounding fluid). The relative velocity that may be detected by the lateral line system is 8-times greater in hatchlings than mature larvae (5-6 dpf) because of the greater density generated by not having an inflated swim bladder. Therefore, flow stimuli are greatly attenuated by the motion of a larva’s body and that this signal is reduced further with the inflation of the swim bladder. These results suggest that lateral line function may change dramatically over the life history of a fish due to the scaling of flow stimuli relative to the size and mass of the body.
