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George V Lauder - One of the best experts on this subject based on the ideXlab platform.
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Structure of supporting elements in the Dorsal Fin of percid fishes.
Journal of morphology, 2017Co-Authors: Alexander F. Weickhardt, Kara Feilich, George V LauderAbstract:The Dorsal Fin is one of the most varied swimming structures in Acanthomorpha, the spiny-Finned fishes. This Fin can be present as a single contiguous structure supported by bony spines and soft lepidotrichia, or it may be divided into an anterior, spiny Dorsal Fin and a posterior, soft Dorsal Fin. The freshwater fish family Percidae exhibits especially great variation in Dorsal Fin spacing, including fishes with separated Fins of varying gap length and fishes with contiguous Fins. We hypothesized that fishes with separated Dorsal Fins, especially those with large gaps between Fins, would have stiffened Fin elements at the leading edge of the soft Dorsal Fin to resist hydrodynamic loading during locomotion. For 10 percid species, we measured the spacing between Dorsal Fins and calculated the second moment of area of selected spines and lepidotrichia from museum specimens. There was no significant relationship between the spacing between Dorsal Fins and the second moment of area of the leading edge of the soft Dorsal Fin.
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Locomotor function of the Dorsal Fin in rainbow trout: kinematic patterns and hydrodynamic forces.
Journal of Experimental Biology, 2005Co-Authors: Eliot G. Drucker, George V LauderAbstract:In this study, we examine the kinematics and hydrodynamics of the soft Dorsal Fin in a representative basal teleost, the rainbow trout (Oncorhynchus mykiss), during steady rectilinear locomotion at 0.5-2.0 body lengths (L) s(-1) and during maneuvering. During steady swimming, Dorsal Fin height and sweep amplitude decrease with increasing speed. The Dorsal Fin wake, as viewed within a horizontal plane, consists of paired vortices on each side of the body (0.5 L s(-1)) or nearly linearly arrayed vortex centers above the body (1.0 L s(-1)) with central jet flows directed predominately laterally (lateral:thrust force ratio = 5-6). At 2.0 L s(-1), the Dorsal Fin is no longer recruited to add momentum to the wake. This pattern of decreasing involvement of the trout Dorsal Fin in thrust production with increasing speed contrasts with the results of our previous study of the soft Dorsal Fin of sunfish (Lepomis), which is hydrodynamically inactive at low speed and sheds a propulsive vortex wake at higher speed. Yawing maneuvers by trout involve unilateral production of a single vortex ring by the Dorsal Fin with a strong jet flow oriented almost directly laterally. During steady swimming, interception by the tail of the Dorsal Fin's vortical wake and the adipose Fin's non-vortical (drag) wake is hypothesized as a mechanism for enhancing tail thrust. This study provides the first experimental evidence that the plesiomorphic soft Dorsal Fin of ray-Finned fishes acts as an ancillary force generator during axial locomotion. We suggest that the distinction often made between median and paired Fin (MPF) propulsion and body and caudal Fin (BCF) propulsion in fishes obscures the important role of multiple propulsors acting in a coordinated fashion. Using a combination of anterior median Fin oscillation and axial undulation, without continuous paired Fin excursions, trout employ an ;M-BCF' gait during steady swimming. The primarily lateral orientation of Dorsal Fin force in trout induces corresponding roll and yaw moments, which must be countered by forces from the caudal, anal and paired Fins. Locomotion in trout therefore involves the simultaneous active use of multiple Fins, presumably to maintain body stability in the face of environmental perturbations.
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Locomotor function of the Dorsal Fin in teleost fishes: experimental analysis of wake forces in sunfish.
The Journal of Experimental Biology, 2001Co-Authors: Eliot G. Drucker, George V LauderAbstract:A key evolutionary transformation of the locomotor system of ray-Finned fishes is the morphological elaboration of the Dorsal Fin. Within Teleostei, the Dorsal Fin primitively is a single midline structure supported by soft, flexible Fin rays. In its derived condition, the Fin is made up of two anatomically distinct portions: an anterior section supported by spines, and a posterior section that is soft-rayed. We have a very limited understanding of the functional significance of this evolutionary variation in Dorsal Fin design. To initiate empirical hydrodynamic study of Dorsal Fin function in teleost fishes, we analyzed the wake created by the soft Dorsal Fin of bluegill sunfish (Lepomis macrochirus) during both steady swimming and unsteady turning maneuvers. Digital particle image velocimetry was used to visualize wake structures and to calculate in vivo locomotor forces. Study of the vortices generated simultaneously by the soft Dorsal and caudal Fins during locomotion allowed experimental characterization of median-Fin wake interactions. During high-speed swimming (i.e. above the gait transition from pectoral- to median-Fin locomotion), the soft Dorsal Fin undergoes regular oscillatory motion which, in comparison with analogous movement by the tail, is phase-advanced (by 30% of the cycle period) and of lower sweep amplitude (by 1.0 cm). Undulations of the soft Dorsal Fin during steady swimming at 1.1 bodylength s(-1) generate a reverse von Kármán vortex street wake that contributes 12% of total thrust. During low-speed turns, the soft Dorsal Fin produces discrete pairs of counterrotating vortices with a central region of high-velocity jet flow. This vortex wake, generated in the latter stage of the turn and posterior to the center of mass of the body, counteracts torque generated earlier in the turn by the anteriorly positioned pectoral Fins and thereby corrects the heading of the fish as it begins to translate forward away from the turning stimulus. One-third of the laterally directed fluid force measured during turning is developed by the soft Dorsal Fin. For steady swimming, we present empirical evidence that vortex structures generated by the soft Dorsal Fin upstream can constructively interact with those produced by the caudal Fin downstream. Reinforcement of circulation around the tail through interception of the Dorsal Fin's vortices is proposed as a mechanism for augmenting wake energy and enhancing thrust. Swimming in fishes involves the partitioning of locomotor force among several independent Fin systems. Coordinated use of the pectoral Fins, caudal Fin and soft Dorsal Fin to increase wake momentum, as documented for L. macrochirus, highlights the ability of teleost fishes to employ multiple propulsors simultaneously for controlling complex swimming behaviors.
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Function of the Dorsal Fin in bluegill sunfish: Motor patterns during four distinct locomotor behaviors
Journal of morphology, 1996Co-Authors: Bruce C. Jayne, Adrian F. Lozada, George V LauderAbstract:The median Fins of fishes are key features of locomotor morphol- ogy which function as complex control surfaces during a variety of behaviors. However, very few studies have experimentally assessed median Fin function, as most workers focus on axial structures. In particular, the Dorsal Fin of many teleost fishes possesses both spiny anterior and soft posterior portions which may function separately during locomotion. We analyzed the function of the soft region of the Dorsal Fin and of the Dorsal inclinator (Di) muscles which are the primary muscles responsible for lateral flexion. We used electromyography to measure in vivo Di activity, as well as activity of the red myomeric muscles located at a similar longitudinal position. We quantified motor patterns during four locomotor behaviors: braking and three propulsive behaviors (steady swimming, kick and glide swimming, and C-starts). During the three propul- sive swimming behaviors, the timing of Di activity was more similar to that of ipsilateral red myomeric muscle rather than to contralateral myomeric activ- ity, whereas during braking the timing of activity of the Di muscles was similar to that of the contralateral myomeric musculature. During the three propul- sive behaviors, when the Di muscles had activity, it was consistent with the function of stiffening the soft Dorsal Fin to oppose its tendency to bend as a result of the body being swept laterally through the water. In contrast, activity of the Di muscles during braking was consistent with the function of actively flexing the soft Dorsal Fin towards the side of the fish that had Di activity. Activity of the Di muscles during steady speed swimming was generally sufficient to resist lateral bending of the soft Dorsal Fin, whereas during high speed kick and glide swimming and C-starts, Di activity was not sufficient to resist the bending caused by resistive forces imposed by the water. Cumulative data from all four behaviors suggest that the Di muscles can be activated independently relative to the myomeric musculature rather than having a single phase relationship with the myomeric muscle common to all of the observed behaviors. o 1996 Wiley-Liss, Inc. The median Fins of most fishes are large, conspicuous structures whose evolutionary origin within the chordate clade probably preceded that of appendicular structures, and yet we presently know remarkably little about how the median Fins function during fish locomotion. This is unfortunate because hy- drodynamic modeling suggests that interspe- cific variation in median Fin morphology is related to differences in the longitudinal dis- tribution of surface area that tend to corre- late with different locomotor tasks such as fast steady swimming, rapid acceleration, and maneuvering (Webb, '84). Our current knowl- edge of the median Fins of teleosts is derived mainly from a small number of studies which are mostly structural and evolutionary in nature, such as Winterbottom's ('74) com- parative descriptions of the median Fin muscles. With the exceptions of the papers by Arita ('71) and Roberts ('69), the overview of Harris ('53), and the work of Geerlink and Videler ('87), who focused on the relation between Fin ray structure and its mechanical
D Ann Pabst - One of the best experts on this subject based on the ideXlab platform.
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using infrared thermography to assess seasonal trends in Dorsal Fin surface temperatures of free swimming bottlenose dolphins tursiops truncatus in sarasota bay florida
Marine Mammal Science, 2009Co-Authors: M M Barbieri, William A Mclellan, James E Blum, Suzanne Hofmann, Janet G Gannon, Randall S Wells, D Ann PabstAbstract:The temperature differential (ΔT) between a body surface and the environment influences an organism's heat balance. In Sarasota Bay, FL, where ambient water temperature (T w ) ranges annually from 11° to 33°C, ΔT was investigated in a resident community of bottlenose dolphins (Tursiops truncatus). Dorsal Fin surface temperatures (T dFin ) were measured on wild, free-swimming dolphins using infrared thermography. Field and laboratory calibration studies were also undertaken to assess the efficacy of this non-invasive technology in the marine environment. The portability of infrared thermography permitted measurements of T dFin across the entire range of environmental temperatures experienced by animals in this region. Results indicated a positive, linear relationship between T dFin and T w (r 2 = 0.978, P < 0.001). On average, T dFin was 0.9°C warmer than T w across seasons, despite the 22°C annual range in T w . Changes in integumentary and vascular insulation likely account for the stability of ΔT dFin-w and the protection of core temperature (T core ) across seasons. The high thermal conductivity of water may also influence this ΔT. The use of infrared thermography is an effective, non-invasive method of assessing Dorsal Fin skin surface temperatures (±1°C) across large numbers of wild, free-swimming dolphins throughout their thermally dynamic aquatic environment.
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The relationship between heat flow and vasculature in the Dorsal Fin of wild bottlenose dolphins Tursiops truncatus.
The Journal of Experimental Biology, 2002Co-Authors: Erin M. Meagher, William A Mclellan, Randall S Wells, Andrew J. Westgate, Dargan Frierson, D Ann PabstAbstract:The Dorsal Fin of the bottlenose dolphin Tursiops truncatus contains blood vessels that function either to conserve or to dissipate body heat. Prior studies have demonstrated that heat flux, measured from a single position on the Dorsal Fin, decreases during body cooling and diving bradycardia and increases after exercise and at the termination of the dive response. While prior studies attributed changes in heat flux to changes in the pattern of blood flow, none directly investigated the influence of vascular structures on heat flux across the Dorsal Fin. In this study we examined whether heat flux is higher directly over a superficial vein, compared to a position away from a vein, and investigated the temporal relationship between heart rate, respiration and heat flux. Simultaneous records of heat flux and skin temperature at three positions on the Dorsal Fins of 19 wild bottlenose dolphins (with the Fin in air and submerged) were collected, together with heart rate and respiration. When the Fin was submerged, heat flux values were highest over superficial veins, usually at the distal tip, suggesting convective delivery of heat, via blood, to the skin’s surface. Conversely, in air there was no relationship between heat flux and superficial vasculature. The mean difference in heat flux (48 W m ‐2 ) measured between the three Fin positions was often equal to or greater than the heat flux that had been recorded from a single position after exercising and diving in prior studies. Tachycardia at a respiratory event was not temporally related to an increase in heat flux across the Dorsal Fin. This study suggests that the Dorsal Fin is a spatially heterogeneous thermal surface and that patterns of heat flux are strongly influenced by underlying vasculature.
Eliot G. Drucker - One of the best experts on this subject based on the ideXlab platform.
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Locomotor function of the Dorsal Fin in rainbow trout: kinematic patterns and hydrodynamic forces.
Journal of Experimental Biology, 2005Co-Authors: Eliot G. Drucker, George V LauderAbstract:In this study, we examine the kinematics and hydrodynamics of the soft Dorsal Fin in a representative basal teleost, the rainbow trout (Oncorhynchus mykiss), during steady rectilinear locomotion at 0.5-2.0 body lengths (L) s(-1) and during maneuvering. During steady swimming, Dorsal Fin height and sweep amplitude decrease with increasing speed. The Dorsal Fin wake, as viewed within a horizontal plane, consists of paired vortices on each side of the body (0.5 L s(-1)) or nearly linearly arrayed vortex centers above the body (1.0 L s(-1)) with central jet flows directed predominately laterally (lateral:thrust force ratio = 5-6). At 2.0 L s(-1), the Dorsal Fin is no longer recruited to add momentum to the wake. This pattern of decreasing involvement of the trout Dorsal Fin in thrust production with increasing speed contrasts with the results of our previous study of the soft Dorsal Fin of sunfish (Lepomis), which is hydrodynamically inactive at low speed and sheds a propulsive vortex wake at higher speed. Yawing maneuvers by trout involve unilateral production of a single vortex ring by the Dorsal Fin with a strong jet flow oriented almost directly laterally. During steady swimming, interception by the tail of the Dorsal Fin's vortical wake and the adipose Fin's non-vortical (drag) wake is hypothesized as a mechanism for enhancing tail thrust. This study provides the first experimental evidence that the plesiomorphic soft Dorsal Fin of ray-Finned fishes acts as an ancillary force generator during axial locomotion. We suggest that the distinction often made between median and paired Fin (MPF) propulsion and body and caudal Fin (BCF) propulsion in fishes obscures the important role of multiple propulsors acting in a coordinated fashion. Using a combination of anterior median Fin oscillation and axial undulation, without continuous paired Fin excursions, trout employ an ;M-BCF' gait during steady swimming. The primarily lateral orientation of Dorsal Fin force in trout induces corresponding roll and yaw moments, which must be countered by forces from the caudal, anal and paired Fins. Locomotion in trout therefore involves the simultaneous active use of multiple Fins, presumably to maintain body stability in the face of environmental perturbations.
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Locomotor function of the Dorsal Fin in teleost fishes: experimental analysis of wake forces in sunfish.
The Journal of Experimental Biology, 2001Co-Authors: Eliot G. Drucker, George V LauderAbstract:A key evolutionary transformation of the locomotor system of ray-Finned fishes is the morphological elaboration of the Dorsal Fin. Within Teleostei, the Dorsal Fin primitively is a single midline structure supported by soft, flexible Fin rays. In its derived condition, the Fin is made up of two anatomically distinct portions: an anterior section supported by spines, and a posterior section that is soft-rayed. We have a very limited understanding of the functional significance of this evolutionary variation in Dorsal Fin design. To initiate empirical hydrodynamic study of Dorsal Fin function in teleost fishes, we analyzed the wake created by the soft Dorsal Fin of bluegill sunfish (Lepomis macrochirus) during both steady swimming and unsteady turning maneuvers. Digital particle image velocimetry was used to visualize wake structures and to calculate in vivo locomotor forces. Study of the vortices generated simultaneously by the soft Dorsal and caudal Fins during locomotion allowed experimental characterization of median-Fin wake interactions. During high-speed swimming (i.e. above the gait transition from pectoral- to median-Fin locomotion), the soft Dorsal Fin undergoes regular oscillatory motion which, in comparison with analogous movement by the tail, is phase-advanced (by 30% of the cycle period) and of lower sweep amplitude (by 1.0 cm). Undulations of the soft Dorsal Fin during steady swimming at 1.1 bodylength s(-1) generate a reverse von Kármán vortex street wake that contributes 12% of total thrust. During low-speed turns, the soft Dorsal Fin produces discrete pairs of counterrotating vortices with a central region of high-velocity jet flow. This vortex wake, generated in the latter stage of the turn and posterior to the center of mass of the body, counteracts torque generated earlier in the turn by the anteriorly positioned pectoral Fins and thereby corrects the heading of the fish as it begins to translate forward away from the turning stimulus. One-third of the laterally directed fluid force measured during turning is developed by the soft Dorsal Fin. For steady swimming, we present empirical evidence that vortex structures generated by the soft Dorsal Fin upstream can constructively interact with those produced by the caudal Fin downstream. Reinforcement of circulation around the tail through interception of the Dorsal Fin's vortices is proposed as a mechanism for augmenting wake energy and enhancing thrust. Swimming in fishes involves the partitioning of locomotor force among several independent Fin systems. Coordinated use of the pectoral Fins, caudal Fin and soft Dorsal Fin to increase wake momentum, as documented for L. macrochirus, highlights the ability of teleost fishes to employ multiple propulsors simultaneously for controlling complex swimming behaviors.
J. B. Rosas-fernández - One of the best experts on this subject based on the ideXlab platform.
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PhotoId-Whale: Blue whale Dorsal Fin classification for mobile devices.
PloS one, 2020Co-Authors: Rosa I. Ramos-arredondo, Blanca E. Carvajal-gámez, Diane Gendron, Francisco J. Gallegos-funes, Dante Mújica-vargas, J. B. Rosas-fernándezAbstract:Photo-identification (photo-id) is a method used in field studies by biologists to monitor animals according to their density, movement patterns and behavior, with the aim of predicting and preventing ecological risks. However, these methods can introduce subjectivity when manually classifying an individual animal, creating uncertainty or inaccuracy in the data as a result of the human criteria involved. One of the main objectives in photo-id is to implement an automated mechanism that is free of biases, portable, and easy to use. The main aim of this work is to develop an autonomous and portable photo-id system through the optimization of image classification algorithms that have high statistical dependence, with the goal of classifying Dorsal Fin images of the blue whale through offline information processing on a mobile platform. The new proposed methodology is based on the Scale Invariant Feature Transform (SIFT) that, in conjunction with statistical discriminators such as the variance and the standard deviation, fits the extracted data and selects the closest pixels that comprise the edges of the Dorsal Fin of the blue whale. In this way, we ensure the elimination of the most common external factors that could affect the quality of the image, thus avoiding the elimination of relevant sections of the Dorsal Fin. The photo-id method presented in this work has been developed using blue whale images collected off the coast of Baja California Sur. The results shown have qualitatively and quantitatively validated the method in terms of its sensitivity, specificity and accuracy on the Jetson Tegra TK1 mobile platform. The solution optimizes classic SIFT, balancing the results obtained with the computational cost, provides a more economical form of processing and obtains a portable system that could be beneficial for field studies through mobile platforms, making it available to scientists, government and the general public.
Li Fei - One of the best experts on this subject based on the ideXlab platform.
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research on swimming by undulatory long Dorsal Fin propulsion
Chinese Journal of Mechanical Engineering, 2006Co-Authors: Li FeiAbstract:The kinematics of steady forward swimming of Gymnarchus niloticus are described. The geometric features of the body and locomotive characteristic and parameters of the flexible Dorsal Fin are discussed. A simplified kinematic model on locomotion of the undulatory long Dorsal Fin propulsion is based on the the observation and experimental data. The hy-dromechanical performances of the undulatory long Dorsal Fin propeller of Gymnarchus niloticus are estimated applying the large-amplitude elongated-body theory. The hydromechanical efficiency of the undulatory long Dorsal Fin system ranged from 82.284% to 87.455% over a speed rang of 0.728-0.985 lengthes· s-1. It is suggested that the undulatory long Dorsal Fin propulsion is an adaptation to swimming with high hydromechanical efficiency.
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Examination and Analysis of Undulatory Dorsal Fin Propulsion of Gymnarchus Niloticus
Journal of National University of Defense Technology, 2006Co-Authors: Li FeiAbstract:This paper introduces the experimental principle and method on undulatory Dorsal Fin propulsion of gymnarchus niloticus,a large aggressive fish whose swimming mode is referred to as amiiform mode.The fish is propelled by undulations of a long-based Dorsal Fin while the body axis is in many cases held straight in swimming.In order to investigate the undulatory Dorsal Fin propulsion and its potential for providing alternative approaches for future underwater vehicle design,the kinematics of steady forward swimming of gymnarchus niloticus was described and the geometric features of the body and locomotive characteristic and parameters of the flexible Dorsal Fin were discussed.Furthermore,a simplified kinematic model on locomotion of the undulatory long Dorsal Fin propulsion was established according to the observation and experimental data.By applying the large-amplitude elongated-body theory,the estimation shows that the hydromechanical efficiency of the undulatory long Dorsal Fin system is more than 83.12%.It is suggested that the undulatory long Dorsal Fin propulsion is an adaptation to swimming with high hydromechanical efficiency.