Meeting Abstract
The cranial lateral line canals (CLLC) of fishes are a mechano-receptive sensory system that can detect pressure gradients caused by changes in flow velocity. The CLLC is phylogenetically conserved, exhibiting a stereotyped, three branch arrangement on each side of the head consisting of a supraorbital branch above the eye (SO), an infraorbital below the eye (IO) and an operculo-mandibular along the lower jaw (OM). Simultaneous recordings from a comprehensive population of lateral line units in behaving animals is currently out of our reach, which has made advancing functional evaluations of CLLC organization challenging. Here we fabricated fish heads from 3D scans of rainbow trout (Oncorhynchus mykiss) to investigate the contributions of each CLLC branch when faced with oncoming flow. We placed pressure sensors in the location of the pores for each CLLC branch and measured the pressure as we varied the yaw and pitch angle of the head from -20° to +20° at 10° intervals. Our results show that the signal to noise ratio of the pressure gradient (PG) across the head is larger than that on the same side of the head. In contrast, pitch angle can be detected only by the PG on the same side of the head. We found that the PGSO > PGIO > PGOM when the pitch angle was positive (e.g. the model was facing down) and that the PGOM > PGIO > PGSO when pitch angle was negative. We also analyzed how pressure varied with head size (14 cm and 8 cm, corresponding to body lengths of 49 and 18 cm, respectively) and flow speed (55 cm s-1 and 26 cm s-1), and found that the signal to noise ratio of the PG increases with head size and flow speed. Our results show that each CLLC branch can provide distinct information during rheotactic behaviour.
