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Article

Volitional Swimming Kinematics of Blacktip Sharks, Carcharhinus limbatus, in the Wild

Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33433, USA
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Author to whom correspondence should be addressed.
Drones 2020, 4(4), 78; https://doi.org/10.3390/drones4040078
Received: 30 September 2020 / Revised: 12 December 2020 / Accepted: 15 December 2020 / Published: 18 December 2020
(This article belongs to the Special Issue Drone Technology for Wildlife and Human Management)
Recent work showed that two species of hammerhead sharks operated as a double oscillating system, where frequency and amplitude differed in the anterior and posterior parts of the body. We hypothesized that a double oscillating system would be present in a large, volitionally swimming, conventionally shaped carcharhinid shark. Swimming kinematics analyses provide quantification to mechanistically examine swimming within and among species. Here, we quantify blacktip shark (Carcharhinus limbatus) volitional swimming kinematics under natural conditions to assess variation between anterior and posterior body regions and demonstrate the presence of a double oscillating system. We captured footage of 80 individual blacktips swimming in the wild using a DJI Phantom 4 Pro aerial drone. The widespread accessibility of aerial drone technology has allowed for greater observation of wild marine megafauna. We used Loggerpro motion tracking software to track five anatomical landmarks frame by frame to calculate tailbeat frequency, tailbeat amplitude, speed, and anterior/posterior variables: amplitude and frequency of the head and tail, and the body curvature measured as anterior and posterior flexion. We found significant increases in tailbeat frequency and amplitude with increasing swimming speed. Tailbeat frequency decreased and tailbeat amplitude increased as posterior flexion amplitude increased. We found significant differences between anterior and posterior amplitudes and frequencies, suggesting a double oscillating modality of wave propagation. These data support previous work that hypothesized the importance of a double oscillating system for increased sensory perception. These methods demonstrate the utility of quantifying swimming kinematics of wild animals through direct observation, with the potential to apply a biomechanical perspective to movement ecology paradigms. View Full-Text
Keywords: aerial drone; body curvature; Carcharhinidae; elasmobranch; flexion; tail beat frequency aerial drone; body curvature; Carcharhinidae; elasmobranch; flexion; tail beat frequency
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MDPI and ACS Style

Porter, M.E.; Ruddy, B.T.; Kajiura, S.M. Volitional Swimming Kinematics of Blacktip Sharks, Carcharhinus limbatus, in the Wild. Drones 2020, 4, 78. https://doi.org/10.3390/drones4040078

AMA Style

Porter ME, Ruddy BT, Kajiura SM. Volitional Swimming Kinematics of Blacktip Sharks, Carcharhinus limbatus, in the Wild. Drones. 2020; 4(4):78. https://doi.org/10.3390/drones4040078

Chicago/Turabian Style

Porter, Marianne E., Braden T. Ruddy, and Stephen M. Kajiura. 2020. "Volitional Swimming Kinematics of Blacktip Sharks, Carcharhinus limbatus, in the Wild" Drones 4, no. 4: 78. https://doi.org/10.3390/drones4040078

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