Pectoral fins aid in navigation of a complex environment by bluegill sunfish under sensory deprivation conditions

Abstract

SUMMARYComplex structured environments offer fish advantages as places of refuge and areas of greater potential prey densities, but maneuvering through these environments is a navigational challenge. To successfully navigate complex habitats, fish must have sensory input relaying information about the proximity and size of obstacles. We investigated the role of the pectoral fins as mechanosensors in bluegill sunfish swimming through obstacle courses under different sensory deprivation and flow speed conditions. Sensory deprivation was accomplished by filming in the dark to remove visual input and/or temporarily blocking lateral line input via immersion in cobalt chloride. Fish used their pectoral fins to touch obstacles as they swam slowly past them under all conditions. Loss of visual and/or lateral line sensory input resulted in an increased number of fin taps and shorter tap durations while traversing the course. Propulsive pectoral fin strokes were made in open areas between obstacle posts and fish did not use the pectoral fins to push off or change heading. Bending of the flexible pectoral fin rays may initiate an afferent sensory input, which could be an important part of the proprioceptive feedback system needed to navigate complex environments. This behavioral evidence suggests that it is possible for unspecialized pectoral fins to act in both a sensory and a propulsive capacity. Supplementary material available online at

Flowing water affects fish fast-starts: escape performance of the Hawaiian stream goby,Sicyopterus stimpsoni

“…In contrast, proprioceptive capacity of the fins (e.g. caudal fin) may facilitate responses to flow pulses from the caudal direction that oppose ambient flow (Flammang and Lauder, 2013;Williams et al, 2013). The strength of a stimulus relative to the strength of alternative environmental cues has been shown to influence the type and number of escape responses in animals, including fish (Abrahams and Kattenfeld, 1997;Domenici, 2010a; D. G. Roche, Effects of biotic and physical stressors on fish swimming performance and behavior, PhD thesis, Australian National University, 2014).…”

Touch sensation by pectoral fins of the catfishPimelodus pictus

“…The fin rays of bluegill sunfish (Lepomis macrochirus), a model species for the study of fin-based propulsion, respond to fin ray deflections and have putative mechanoreceptor structures associated with nerves that run along the fin rays from base to distal tip [4]. The ability of L. macrochirus to interpret the movement and position of their fins, a form of mechanosensation distinct from the sensation of surface touch, is important for navigating complex environments [5] and modulating rhythmic fin movements [6]. While a key feature of the tetrapod somatosensory system is the tactile perception of object movement over the skin, it is unknown whether membranous fins may function as passive touch sensors in the absence of extensive fin movement.…”

Investigation of Fish Caudal Fin Locomotion Using a Bio-Inspired Robotic Model

“…As many recent studies have reported that fish can actively deform their fins to achieve different types of locomotion, more and more researchers have realized the importance of these flexible propulsion surfaces on enchancing ability of swimming. Such propulsion surfaces include dorsal fins [2][3][4] and pectoral fins [5][6][7] in body and caudal fin (BCF) propulsion and ribbon fins [8][9][10] in median and paired fin (MPF) propulsion. As the most conspicuous appendage of the fish's body, the caudal fin has also been studied extensively [11][12][13][14][15].…”