Meeting Abstract
Remoras are fishes that attach to marine organisms that swim at a wide range of different speeds. In order to attach to an actively moving host organism, remoras must approach, attach, and adhere under hydrodynamic conditions that exceed those of their normal, individual swimming speed. To date, no research has been done on the hydrodynamics of remora attachment under different speed conditions. We visualized the flow around euthanized remora (Echeneis naucrates) and cobia (Rachycentron canadum, nearest relative to remoras) moved toward and away from a wall in freestream velocities ranging from 0.01 to 1.16 m/s. Using pressures calculated from a straightforward application of the Bernoulli equation in regions of the flow likely dominated by inertial forces, we show that as the remora approaches a host body a suction effect is created between the disc and host as flow is accelerated relative to free stream. This suction effect was observed both in approach and immediately following detachment of the remora. We also found that the flat disc surface of the remora approximately doubled the suction effect resulting from wall interaction as compared to cobia, which lacks a disc but is otherwise morphologically similar in body shape. We hypothesize that the general flat disc shape of the remora adhesive mechanism may contribute to initial attachment, particularly under high-velocity conditions.
