Knifefish turning control and hydrodynamics during forward swimming

• DOI: 10.1242/jeb.243498
• Publication Date: 2022-02-26T03:23:17Z
• Authors: Olivia H. Hawkins; Víctor M. Ortega-...; Christopher P. Sa...
• Keywords: 0209 industrial biotechnology; Animal Fins; Gymnotiformes; Hydrodynamics; Animals; 02 engineering and technology; 14. Life underwater; Rheology; Swimming; Biomechanical Phenomena

Rapid turning and swimming contribute to ecologically important behaviors in fishes such as predator avoidance, prey capture, mating the navigation of complex environments. For riverine species, knifefishes, may also be for navigating locomotive perturbations caused by turbulent flows. Most research on fish maneuvering focuses with traditional fin body morphologies, which primarily use bending pectoral fins during turning. However, it is uncertain how uncommon morphologies are able achieve sudden controllable turns. Here, we studied performance hydrodynamics black ghost knifefish (Apteronotus albifrons, N=6) has an atypical elongated ribbon fin. Fish were filmed while forward at ∼2 lengths s-1 feeding from a fixed feeder (control) oscillating (75 Hz) two different amplitudes. 3D kinematic analysis revealed highest pitch angles lowest coefficients steady swimming. Low angle, high maximum yaw large characteristic small Asynchrony was low turning; however, wavelength, frequency wave speed greatest Digital particle image velocimetry (DPIV) showed larger counter-rotating vortex pairs produced comparison vortices rotating same direction Our results highlight fin's role controlled rapid through modulation speed.