Locomotor function of the dorsal fin in teleost fishes: experimental analysis of wake forces in sunfish

2001 ◽  
Vol 204 (17) ◽  
pp. 2943-2958 ◽  
Author(s):  
Eliot G. Drucker ◽  
George V. Lauder
Keyword(s):  
High Speed ◽  
Lepomis Macrochirus ◽  
The Body ◽  
Cycle Period ◽  
Teleost Fishes ◽  
Caudal Fin ◽  
Locomotor System ◽  
Pectoral Fins ◽  
Dorsal Fin

SUMMARYA 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 1.0cm). Undulations of the soft dorsal fin during steady swimming at 1.1bodylengths−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.

Learning From the Fins of Ray-Finned Fish for the Propulsors of Unmanned Undersea Vehicles

2011 ◽  
Vol 45 (4) ◽  
pp. 65-73 ◽  
Author(s):  
James L. Tangorra ◽  
Timo Gericke ◽  
George V. Lauder
Keyword(s):  
High Speed ◽  
The Body ◽  
External Disturbances ◽  
Pectoral Fins ◽  
Autonomous Regulation ◽  
Wide Range ◽  
Sensorimotor Systems ◽  
And Control ◽  
Vortex Perturbations

AbstractAdvanced propulsors are required to help unmanned undersea vehicles (UUVs) overcome major challenges associated with energy and autonomy. The fins of ray-finned fish provide an excellent model from which to develop propulsors that can create forces efficiently and drive a wide range of behaviors, from hover to low-speed maneuvers to high-speed travel. Although much is known about the mechanics of fins, little is known about the fin’s sensorimotor systems or how fins are regulated in response to external disturbances. This information is crucial for implementing propulsive and control systems that exploit the same phenomena as the biological fins for efficiency, effectiveness, and autonomous regulation. Experiments were conducted to evaluate the in vivo response of the sunfish and its pectoral fins to vortex perturbations applied directly to the fish and to the fins. The fish and the fins responded actively to perturbations that disturbed the motion of the fish body. Surprisingly, perturbations that deformed the fins extensively did not cause a reaction from either the fins or the body. These results indicate that the response of the pectoral fins to large deformations is not reflexive and that fin motions are regulated when it is necessary to correct for disturbances to the motion of the fish. The results also demonstrate a benefit of compliance in propulsors, in that external perturbations can disturb the fins without having its impact be transferred to the fish body.

II.—New Palæoniscidæ from the English Coal-Measures

1888 ◽  
Vol 5 (6) ◽  
pp. 251-254 ◽  
Author(s):  
R. H. Traquair
Keyword(s):  
The Body ◽  
The Other ◽  
Caudal Fin ◽  
Dorsal Fin ◽  
Coal Measures

Of this I have seen only two specimens. One of them, slightly longer than the other, measures 3½ inches in length up to the commencement of the caudal fin, which is deficient in both; the greatest depth of the body ½½ inch, the length of the head nearly the same. The dorsal fin is opposite the interval between the ventral and the anal; both dorsal and anal are triangular acuminate in shape, with delicate rays which at first are somewhat distantly articulated, the joints being ornamented with one or two longitudinal sulci. The pectorals are not seen in either specimen, but the smaller of the two shows a well-preserved ventral, which is pretty large, and acuminate in shape.

Quantitative analysis of prey-capture kinematics in Anolis equestris (Reptilia: Iguanidae)

1990 ◽  
Vol 68 (10) ◽  
pp. 2192-2198 ◽  
Author(s):  
Vincent L. Bels
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Anterior Part ◽  
The Body ◽  
Original Position ◽  
Forward Movement ◽  
Live Prey ◽  
Capture Process ◽  
Locomotor System ◽  
Cyclic Movement

High-speed cinematography was employed to study the mechanics of prey capture in Anolis equestris. Capture of live prey (adult locusts) consists of a cyclic movement of the upper and lower jaws combined with tongue protraction. Kinematic profiles are presented for the jaws, tongue, and forelimbs. The tongue is projected during the "slow open" stage and most of the "fast open" stage. The tongue protrudes beyond the mandibular symphysis during the slow open stage, and rotates simultaneously around a transverse anteromedian axis. The prey is thus contacted by the dorsal sticky surface of the tongue, and then pulled backward into the oral cavity by a combination of a forward movement of the jaws and retraction of the tongue. Gape angle, defined as the angle between the upper and lower jaws, continues to increase during the initial stages of tongue retraction. During the capture process, the anterior part of the body lunges forward, followed by a return to its original position; this displacement is mediated by the forelimbs, which usually remain well anchored to the floor. The cyclic food-capture movements of the jaws and tongue–hyoid system in A. equestris (Iguanidae) and Chameleo dilepis (Chamaeleontidae) are compared. I argue that one of the primary selection forces in the evolution of the different mechanisms of prey prehension in these two lizard groups was enhancement of the locomotor system and, consequently, foraging ability.

scholarly journals Hydrodynamics of linear acceleration in bluegill sunfish Lepomis macrochirus

2018 ◽  
Author(s):  
Tyler N. Wise ◽  
Margot A. B. Schwalbe ◽  
Eric D. Tytell
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Fluid Dynamic ◽  
Natural Habitat ◽  
Lepomis Macrochirus ◽  
Linear Acceleration ◽  
High Amplitude ◽  
The Body ◽  
Bluegill Sunfish ◽  
Tail Beat

SUMMARY STATEMENTBluegill sunfish accelerate primarily by increasing the total amount of force produced in each tail beat but not by substantially redirecting forces.ABSTRACTIn their natural habitat, fish rarely swim steadily. Instead they frequently accelerate and decelerate. Relatively little is known about how fish produce extra force for acceleration in routine swimming behavior. In this study, we examined the flow around bluegill sunfish Lepomis macrochirus during steady swimming and during forward acceleration, starting at a range of initial swimming speeds. We found that bluegill produce vortices with higher circulation during acceleration, indicating a higher force per tail beat, but do not substantially redirect the force. We quantified the flow patterns using high speed video and particle image velocimetry and measured acceleration with small inertial measurement units attached to each fish. Even in steady tail beats, the fish accelerates slightly during each tail beat, and the magnitude of the acceleration varies. In steady tail beats, however, a high acceleration is followed by a lower acceleration or a deceleration, so that the swimming speed is maintained; in unsteady tail beats, the fish maintains the acceleration over several tailbeats, so that the swimming speed increases. We can thus compare the wake and kinematics during single steady and unsteady tailbeats that have the same peak acceleration. During unsteady tailbeats when the fish accelerates forward for several tailbeats, the wake vortex forces are much higher than those at the same acceleration during single tailbeats in steady swimming. The fish also undulates its body at higher amplitude and frequency during unsteady tailbeats. These kinematic changes likely increase the fluid dynamic added mass of the body, increasing the forces required to sustain acceleration over several tailbeats. The high amplitude and high frequency movements are also likely required to generate the higher forces needed for acceleration. Thus, it appears that bluegill sunfish face a tradeoff during acceleration: the body movements required for acceleration also make it harder to accelerate.

Pelvicachromis signatus and Pelvicachromis rubrolabiatus, two new cichlid species (Teleostei, Perciformes) from Guinea, West Africa

Zootaxa ◽  
2004 ◽  
Vol 454 (1) ◽  
pp. 1 ◽  
Author(s):  
ANTON LAMBOJ
Keyword(s):  
West Africa ◽  
Black Spot ◽  
Color Pattern ◽  
The Body ◽  
Caudal Peduncle ◽  
Caudal Fin ◽  
Cichlid Species ◽  
Dorsal Fin ◽  
Black Spots ◽  
Vertical Bars

Pelvicachromis rubrolabiatus and P. signatus are described from Guinea. They differ from other members of Pelvicachromis, except P. humilis, in having two contiguous tubular infraorbital ossicles instead of three with a gap between the 2 nd and 3 rd and in displaying a color pattern of seven to eight dark vertical bars during certain behavioral situations. Pelvicachromis rubrolabiatus differs from P. humilis and P. signatus in having seven instead of eight vertical bars on the body and from P. signatus in having a lesser preorbital depth. Pelvicachromis signatus differs from P. humilis in the presence of characteristic black markings in the dorsal and caudal fin of males, a black spot on the caudal peduncle of females and occasionally one or two black spots in the female s dorsal fin.

Swimming in needlefish (Belonidae): anguilliform locomotion with fins

2002 ◽  
Vol 205 (18) ◽  
pp. 2875-2884 ◽  
Author(s):  
James C. Liao
Keyword(s):  
Surface Waters ◽  
High Speed ◽  
Total Body Length ◽  
The Body ◽  
Pectoral Fins ◽  
Half Wavelength ◽  
Total Body ◽  
Length Analysis ◽  
Median Fins ◽  
Tail Beat

SUMMARYThe Atlantic needlefish (Strongylura marina) is a unique anguilliform swimmer in that it possesses prominent fins, lives in coastal surface-waters, and can propel itself across the surface of the water to escape predators. In a laboratory flow tank, steadily swimming needlefish perform a speed-dependent suite of behaviors while maintaining at least a half wavelength of undulation on the body at all times. To investigate the effects of discrete fins on anguilliform swimming, I used high-speed video to record body and fin kinematics at swimming speeds ranging from 0.25 to 2.0 Ls-1 (where L is the total body length). Analysis of axial kinematics indicates that needlefish are less efficient anguilliform swimmers than eels, indicated by their lower slip values. Body amplitudes increase with swimming speed, but unlike most fishes, tail-beat amplitude increases linearly and does not plateau at maximal swimming speeds. At 2.0 Ls-1, the propulsive wave shortens and decelerates as it travels posteriorly, owing to the prominence of the median fins in the caudal region of the body. Analyses of fin kinematics show that at 1.0 Ls-1 the dorsal and anal fins are slightly less than 180° out of phase with the body and approximately 225° out of phase with the caudal fin. Needlefish exhibit two gait transitions using their pectoral fins. At 0.25 L s-1, the pectoral fins oscillate but do not produce thrust, at 1.0 L s-1 they are held abducted from the body,forming a positive dihedral that may reduce rolling moments, and above 2.0 L s-1 they remain completely adducted.

1. On New and Little-known Fossil Fishes from the Edinburgh District. No. III

1878 ◽  
Vol 9 ◽  
pp. 427-444
Author(s):  
R. H. Traquair
Keyword(s):  
Extreme Point ◽  
Anterior Part ◽  
Lower Lobe ◽  
The Body ◽  
Post Mortem ◽  
Caudal Fin ◽  
Dorsal Fin ◽  
Science And Art ◽  
Peculiar Form ◽  
General Appearance

Elonichthys ovatus, sp. nov. Traquair.Of this I have only seen one specimen, from the limestone of Burdiehouse, and preserved in the Edinburgh Museum of Science and Art.Description.—Allowing for the anterior part of the head, which is deficient, the entire length of the specimen to the extreme point of the upper lobe of the caudal fin would be about 5⅝ inches; the greatest depth of the body in front of the dorsal fin is 1½ inch. The distance from the origin of the pectoral fin to that of the ventral is a little over 1 inch, to opposite the commencement of the dorsal 1¼ inch, to opposite that of the anal 1½ inch, and to opposite that of the lower lobe of the caudal nearly 3 inches. The general form of the fish is thus remarkably short, deep, and ovoid, and its general appearance does not indicate that its peculiar form is due to post mortem distortion or change.

Schistura madhavai, a new species of hill-stream loach from Sri Lanka, with redescription of S. notostigma (Teleostei: Nemacheilidae)

Zootaxa ◽  
2017 ◽  
Vol 4311 (1) ◽  
pp. 96 ◽  
Author(s):  
HIRANYA SUDASINGHE
Keyword(s):  
New Species ◽  
Sri Lanka ◽  
Lateral Line ◽  
The Body ◽  
Pairwise Distance ◽  
Caudal Fin ◽  
Dorsal Fin ◽  
Fin Ray ◽  
Line Ending ◽  
Pelvic Fin

Schistura madhavai, new species, is described from Suriyakanda, Sri Lanka. It is distinguished from all other species of Schistura in the peninsula of India and Sri Lanka by the combination of the following characters: 8–9 wide, brown postdorsal bars separated by narrow, white interspaces; width of interspaces ¼–⅓ times width of bars; black bar at caudal-fin base wider than interspaces on the body; incomplete lateral line, ending beneath dorsal-fin base; absence of an axillary pelvic lobe; adpressed pelvic fin just reaching anus; origin of the pelvic fin on a vertical through the last unbranched dorsal-fin ray. Schistura notostigma, the only other Sri Lankan species of Schistura, is redescribed. It can be distinguished from all other species of Schistura in the peninsula of India and Sri Lanka by the combination of the following characters: 6–7 wide, brown postdorsal bars; width of interspaces ½–1 times width of bars; complete, black bar at caudal-fin base narrower than width of interspaces between bars on body; emarginate caudal fin; incomplete lateral line ending beneath dorsal-fin base; adpressed pelvic fin surpassing anus; and origin of pelvic fin beneath first branched dorsal-fin ray. Schistura madhavai is separated from S. notostigma by an uncorrected pairwise distance of 3.0–3.8% for the 16S rRNA gene fragment. 

Site specificity of Gyrodactylus salaris Malmberg, 1957 (Monogenea) on Atlantic salmon (Salmo salar L.) in the River Lakselva, northern Norway

1992 ◽  
Vol 70 (2) ◽  
pp. 264-267 ◽  
Author(s):  
Arne Johan Jensen ◽  
Bjørn Ove Johnsen
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Infection Intensity ◽  
The Body ◽  
Site Specificity ◽  
Caudal Fin ◽  
Northern Norway ◽  
Dorsal Fin ◽  
Atlantic Salmon Salmo Salar

Site specificity of Gyrodactylus salaris on 853 Atlantic salmon (Salmo salar) parr infected with 1 – 10 625 parasites was studied in the River Lakselva in northern Norway. At low intensities (< 100), the dorsal fin was the principal site of attachment, followed by the pectoral and anal fins. However, the distribution of parasites on the fish, and their crowding, varied with infection intensity. When the intensity increased to more than 100, more parasites were located on the caudal fin, and when it exceeded 1000, the body of the fish was also heavily infected.

scholarly journals A new species of Gymnelus (Perciformes, Zoarcidae) from Greenland, similar to G. viridis

2021 ◽  
Vol 325 (1) ◽  
pp. 34-48
Author(s):  
N.V. Chernova ◽  
P.R. Møller
Keyword(s):  
New Species ◽  
North Pacific Ocean ◽  
Original Description ◽  
The Body ◽  
The Arctic ◽  
West Greenland ◽  
Pectoral Fins ◽  
Dorsal Fin ◽  
South West ◽  
A New Species

Zoarcid fishes of the genus Gymnelus Reinhardt inhabit the shelves of the North Pacific Ocean and the Arctic. A new species, G. pseudosquamatus sp. nov., is described from trawl samples taken at depths off South-West Greenland. It is most similar to the type species of the genus, Common Fish Doctor G. viridis, inhabiting the coastal waters of Greenland. The characters of the latter are specified on materials from the type locality, including the neotype and specimens of J.C.H. Reinhardt. Both species are in the group of Gymnelus with an interrupted supratemporal commissura, two supratemporal sensory pores (1+0+1), and a dorsal fin originating above the pectoral fin. The two species differ in a complex of characters, including habitus. In G. viridis, the trunk is roundish in cross section, highest above the beginning of the anal fin; the anterior rays of the dorsal fin are shortened, and covered with a thick and somewhat fleshy skin. In G. pseudosquamatus, the body is compressed and deeper anteriorly, the dorsal-fin rays are evenly elongated, and the fin membrane is thin. Differences in counts and measurements are statistically significant, including the number of vertebrae and rays in the dorsal, anal and pectoral fins, the number of teeth on the jaws, as well as the length and depth of the head, predorsal length, the length of pectoral fins, eye diameter and length of the gill slit. The color of G. pseudosquamatus, with 8–16 wide brown mottled bands, is also unusual, as the skin is dotted with light speckles that create the illusion of tiny scales, which is the reason for the name “pseudosquamatus”, the Deceptive Fish Doctor. While G. viridis is found inshore in a zone of macroalgae, the new species is found in deeper waters (100–457 m) along the shelf edge of South-West Greenland. The name Ophidium stigma Lay et Bennett, 1839 (=Gymnelus stigma) should be excluded from the synonymy of G. viridis, since the original description mentions the presence of scales on the body, which are absent in Gymnelus.

Sign in / Sign up

Export Citation Format

Share Document