Fin ray sensation participates in the generation of normal fin movement in the hovering behavior of the bluegill sunfish (Lepomis macrochirus).

Abstract

For many fish species, the pectoral fins serve as important propulsors and stabilizers and are precisely controlled. Although it has been shown that mechanosensory feedback from the fin ray afferent nerves provides information on ray bending and position, the effects of this feedback on fin movement are not known. In other taxa, including insects and mammals, sensory feedback from the limbs has been shown to be important for control of limb-based behaviors and we hypothesized that this is also the case for the fishes. In this study, we examined the impact of the loss of sensory feedback from the pectoral fins on movement kinematics during hover behavior. Research was performed with bluegill sunfish (Lepomis macrochirus), a model for understanding the biomechanics of swimming and for bio-inspired design of engineered fins. The bluegill beats its pectoral fins rhythmically, and in coordination with pelvic and median fin movement, to maintain a stationary position while hovering. Bilateral deafferentation of the fin rays results in a splay-finned posture where fins beat regularly but at a higher frequency and without adducting fully against the side of the body. For unilateral transections, more irregular changes in fin movements were recorded. These data indicate that sensory feedback from the fin rays and membrane is important for generating normal hover movements but is not necessary for generating rhythmic fin movement.

Mechanosensation is evolutionarily tuned to locomotor mechanics

“…For example, people who have lost mechanosensation of their limbs must attend visually to their affected limbs to know where they are in space and to modulate motor output effectively (7,8). Experimental sensory denervation of limbs (9)(10)(11)(12) and other appendages (13)(14)(15) in a range of other species has also been shown to result in significant disruption of normal movement. The recent discovery of mechanosensation in the pectoral fins of fishes (15)(16)(17) provides an opportunity to explore evolutionary patterns of mechanosensation relative to interspecific variation in limb locomotor biomechanics.…”

“…In this study, we investigated the correlated evolution of mechanosensation and limb mechanics in fish pectoral fins, the homologs of tetrapod forelimbs. Pectoral fin nerves have recently been shown to provide feedback on fin ray bending amplitude and rate as well as on fin ray position (15,16). Here we examined proprioception in the fish family Labridae (wrasses), a group that demonstrates considerable morphological, biomechanical, and movement diversity (33).…”

Mechanosensation in an adipose fin

“…Future work should evaluate the mechanosensitive capabilities of adipose fins in salmonids. Additionally, particle imaging velocimetry [22] and nerve transections [18] can be used to Table 1. A comparison of spike rate during the hold period of a stimulus and baseline.…”

Muscle Spindle and Comparison of Fish Muscle Spindle with Other Vertebrates

“…The study has conducted on the salmon muscle spinde hasn't refer to the motor innervation and at the same time there have been many studies on innervation of extrafusal fibers (Johnston and Moon, 1981) and also physiological studies about fish proprioception (Williams and Hale, 2015;Rivera et al, 2014) where they have mentioned that the sense of position and movement of the paired and/or unpaired fins is critical for executing rapid motor behavior in fishes. However, the location of the proprioceptive receptors involved in proprioception of fin movement is unknown.…”