Functional morphology of the pectoral fins in bamboo sharks, Chiloscyllium plagiosum: Benthic vs. Pelagic station‐holding

Bamboo sharks (Chiloscyllium plagiosum) are primarily benthic and use their relatively flexible pectoral and pelvic fins to rest on and move about the substrate. We examined the morphology of the pectoral fins and investigated their locomotory function to determine if pectoral fin function during both benthic station‐holding and pelagic swimming differs from fin function described previously in leopard sharks, Triakis semifasciata. We used three‐dimensional kinematics and digital particle image velocimetry (DPIV) to quantify pectoral fin function in five white‐spotted bamboo sharks, C. plagiosum, during four behaviors: holding station on the substrate, steady horizontal swimming, and rising and sinking during swimming. During benthic station‐holding in current flow, bamboo sharks decrease body angle and adjust pectoral fin angle to shed a clockwise fluid vortex. This vortex generates negative lift more than eight times that produced during open water vertical maneuvering and also results in an upstream flow that pushes against the posterior surface of the pectoral fin to oppose drag. In contrast, there is no evidence of significant lift force in the wake of the pectoral fin during steady horizontal swimming. The pectoral fin is held concave downward and at a negative dihedral angle during steady horizontal swimming, promoting maneuverability rather than stability, although this negative dihedral angle is much less than that observed previously in sturgeon and leopard sharks. During sinking, the pectoral fins are held concave upward and shed a clockwise vortex with a negative lift force, while in rising the pectoral fin is held concave downward and sheds a counterclockwise vortex with a positive lift force. Bamboo sharks appear to sacrifice maneuverability for stability when locomoting in the water column and use their relatively flexible fins to generate strong negative lift forces when holding position on the substrate and to enhance stability when swimming in the water column. J. Morphol. 249:195–209, 2001. © 2001 Wiley‐Liss, Inc.

[1]  J. R. Simons.  The Direction of the Thrust Produced by the Heterocercal Tails of Two Dissimilar Elasmobranchs: The Port Jackson Shark, Heterodontus Portusjacksoni (Meyer), and the Piked Dogfish, Squalus Megalops (Macleay) , 1970 .

[2]  Lauder,et al.  Locomotion in sturgeon: function of the pectoral fins. , 1999, The Journal of experimental biology.

[3]  Lauder,et al.  Heterocercal tail function in leopard sharks: a three-dimensional kinematic analysis of two models , 1996, The Journal of experimental biology.

[4]  J. Videler.  Fish Swimming , 1993, Springer Netherlands.

[5]  D. Weihs,et al.  The Hydrodynamics of Rheotaxis in the Plaice (Pleuronectes Platessa L.) , 1978 .

[6]  Keith Stewart Thomson,et al.  On the heterocercal tail in sharks , 1976, Paleobiology.

[7]  Lauder,et al.  Locomotor forces on a swimming fish: three-dimensional vortex wake dynamics quantified using digital particle image velocimetry. , 1999, The Journal of experimental biology.

[8]  C. Ireland.  Fundamental concepts in the design of experiments , 1964 .

[9]  Lauder,et al.  Are muscle fibers within fish myotomes activated synchronously? Patterns of recruitment within deep myomeric musculature during swimming in largemouth bass , 1995, The Journal of experimental biology.

[10]  Martin Simons,et al.  Model Aircraft Aerodynamics , 1983 .

[11]  P. Motta,et al.  Evolution of jaw depression mechanics in aquatic vertebrates: insights from Chondrichthyes , 2000 .

[12]  G. Lauder,et al.  Three-dimensional kinematics and wake structure of the pectoral fins during locomotion in leopard sharks Triakis semifasciata. , 2000, The Journal of experimental biology.

[13]  Paul W. Webb,et al.  The station-holding performance of the plaice Pleuronectes platessa on artificial substratum ripples , 1998 .

[14]  Leonie Kohl,et al.  Fundamental Concepts in the Design of Experiments , 2000 .

[15]  P. Webb.  THE EFFECT OF SOLID AND POROUS CHANNEL WALLS ON STEADY SWIMMING OF STEELHEAD TROUT ONCORHYNCHUS MYKISS , 1993 .

[16]  L. Compagno,et al.  Sharks of the Order Carcharhiniformes , 1988 .

[17]  Paul W. Webb,et al.  Station-holding by the mottled sculpin, Cottus bairdi (Teleostei: Cottidae), and other fishes , 1996 .

[18]  Frank E. Fish,et al.  The role of the pectoral fins in body trim of sharks , 2000 .

[19]  G. Arnold.  A Flume For Behaviour Studies of Marine Fish , 1969 .

[20]  M. Dickinson.  UNSTEADY MECHANISMS OF FORCE GENERATION IN AQUATIC AND AERIAL LOCOMOTION , 1996 .

[21]  Wilga,et al.  Feeding mechanism of the atlantic guitarfish rhinobatos lentiginosus: modulation of kinematic and motor activity , 1998, The Journal of experimental biology.

[22]  Paul W. Webb,et al.  STATION-HOLDING BY THREE SPECIES OF BENTHIC FISHES , 1989 .

[23]  Paul W. Webb,et al.  The role of the pectoral fins in station-holding of Atlantic salmon Parr (Salmo salar L.) , 1991 .

[24]  L. Compagno,et al.  Sharks of the World , 1985 .

[25]  George V. Lauder,et al.  Pectoral Fin Locomotion in Fishes: Testing Drag-based Models Using Three-dimensional Kinematics , 1996 .

[26]  R. Alexander,et al.  THE LIFT PRODUCED BY THE HETEROCERCAL TAILS OF SELACHII , 1965 .

[27]  George V. Lauder,et al.  Function of the Caudal Fin During Locomotion in Fishes: Kinematics, Flow Visualization, and Evolutionary Patterns1 , 2000 .

[28]  Markus Raffel,et al.  Particle Image Velocimetry: A Practical Guide , 2002 .

[29]  Pingguo He,et al.  Tilting behaviour of the Atlantic mackerel, Scomber scombrus, at low swimming speeds , 1986 .

[30]  Wilga,et al.  Conservation and variation in the feeding mechanism of the spiny dogfish squalus acanthias , 1998, The Journal of experimental biology.