Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild
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, conventionall...
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doaj-aad6487fb16b4f4c9cff32f5eee49e2a2020-12-19T00:05:38ZengMDPI AGDrones2504-446X2020-12-014787810.3390/drones4040078Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the WildMarianne E. Porter0Braden T. Ruddy1Stephen M. Kajiura2Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33433, USADepartment of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33433, USADepartment of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33433, USARecent 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 (<i>Carcharhinus limbatus</i>) 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.https://www.mdpi.com/2504-446X/4/4/78aerial dronebody curvatureCarcharhinidaeelasmobranchflexiontail beat frequency |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Marianne E. Porter Braden T. Ruddy Stephen M. Kajiura |
spellingShingle |
Marianne E. Porter Braden T. Ruddy Stephen M. Kajiura Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild Drones aerial drone body curvature Carcharhinidae elasmobranch flexion tail beat frequency |
author_facet |
Marianne E. Porter Braden T. Ruddy Stephen M. Kajiura |
author_sort |
Marianne E. Porter |
title |
Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild |
title_short |
Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild |
title_full |
Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild |
title_fullStr |
Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild |
title_full_unstemmed |
Volitional Swimming Kinematics of Blacktip Sharks, <i>Carcharhinus limbatus</i>, in the Wild |
title_sort |
volitional swimming kinematics of blacktip sharks, <i>carcharhinus limbatus</i>, in the wild |
publisher |
MDPI AG |
series |
Drones |
issn |
2504-446X |
publishDate |
2020-12-01 |
description |
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 (<i>Carcharhinus limbatus</i>) 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. |
topic |
aerial drone body curvature Carcharhinidae elasmobranch flexion tail beat frequency |
url |
https://www.mdpi.com/2504-446X/4/4/78 |
work_keys_str_mv |
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