Role of skin protrusions The V-shaped protrusions on the sailfish skin did not reduce the skin friction in a turbulent boundary layer but each of them produced a pair of streamwise vortices that might be related to a delay of turbulent separation [31]. Role of bill As mentioned in the Introduction , possibilities of reducing drag by the bill have been suggested before [5] , [7] , [10] , [29] , [30] , [38].
Figure 7. Variations of the drag and drag coefficient from those with the original bill. Figure 9. Velocity profiles over the body surface of the sailfish with different bills. Figure Velocity profiles over the body surface of the swordfish with different bills. Concluding remarks Motivated by their fast swimming speeds and peculiar shapes, we investigated the hydrodynamic characteristics of the sailfish and swordfish at their cruise speeds by installing taxidermy specimens in a wind tunnel, directly measuring the drags on the bodies, and probing the boundary layer velocities above the body surfaces.
Acknowledgments We appreciate the cooperation from the Korea Research Center of Maritime Animals for taxidermy specimens of the sailfish and swordfish. References 1. Berkely: University of California Press. Lane FW How fast do fish swim? Ctry Life: — J Fish Biol.
View Article Google Scholar 4. Walters V Body form and swimming performance in the scombroid fishes. Am Zool 2: — View Article Google Scholar 5. Ovchinnikov VV Turbulence in the boundary layer as a method for reducing the resistance of certain fish on movement.
Biophysics — View Article Google Scholar 6. Ovchinnikov VV Swordfishes and billfishes in the Atlantic Ocean — ecology and functional morphology. Aleyev YG Nekton. The Hague: Junk, p. Nakamura I FAO species catalogue. Billfishes of the world. An annotated and illustrated catalogue of marlins, sailfishes, spearfishes, and swordfishes known to date. FAO Fish Synop 5: 1— View Article Google Scholar 9.
J Exp Biol — View Article Google Scholar Videler JJ Body surface adaptations to boundary-layer dynamics. Biological Fluid Dynamics. London: Soc Exp Biol Symp. Copeia 2 : — Hoolihan JP Horizontal and vertical movements of sailfish Istiophorus platypterus in the Arabian Gulf, determined by ultrasonic and pop-up satellite tagging.
Mar Biol — Borazjani I, Sotiropoulos F Numerical investigation of the hydrodynamics of carangiform swimming in the transitional and inertial flow regimes. Borazjani I, Sotiropoulos F Numerical investigation of the hydrodynamics of anguilliform swimming in the transitional and inertial flow regimes. Proc R Soc B : — J Fluid Mech 5— J Fluid Mech R3. Drucker EG, Lauder GV Locomotor forces on a swimming fish: three-dimensional vortex wake dynamics quantified using digital particle image velocimetry.
Drucker EG, Lauder GV Experimental hydrodynamics of fish locomotion: functional insights from wake visualization.
Integ Comp Biol — Allan WH Underwater flow visualization techniques. J Exp Biol 81— Webb PW Hydrodynamics and energetics of fish propulsion. Bull Fish Res Board Can 1— Annu Rev Fluid Mech 65— Phys Fluids Walsh MJ Turbulent boundary layer drag reduction using riblets. J Fluid Mech — J Fluid Mech 59— Copeia 2 : Copeia 4 : — Bull Mar Sci — Kozlov LF Hydrodynamic function of the rostrum of the swordfish.
Han M Method of making a stuffed fish. KR Patent Korean Intellectual Property Office. Park H, Choi H Aerodynamic characteristics of flying fish in gliding flight. Exp Mech — Magnuson JJ Comparative study of adaptations for continuous swimming and hydrostatic equilibrium of scombroid and xiphoid fishes. Fish Bull — J Hydraul Div — Lighthill MJ Note on the swimming of slender fish. J Fluid Mech 9: — Lighthill MJ Aquatic animal propulsion of high hydrodynamic efficiency.
Lighthill MJ Large-amplitude elongated-body theory of fish locomotion. Proc R Soc Lond B — Annu Rev Fluid Mech — Enfield : Science Publishers. Lighthill MJ Hydromechanics of aquatic animal propulsion. Annu Rev Fluid Mech 1: — People do not keep these fish in aquariums. They live pelagic and migratory lifestyles, and their long bills can easily become damaged from hitting the sides of an aquarium.
These fish live in small groups or alone as adults. Juveniles congregate into larger schools. They spend most of their time swimming near the surface of the water in search of prey. Seasonally, they undergo long migrations. These fish reproduce via spawning, where the females release their eggs and the males fertilize them outside of the body.
The females use their dorsal fins to attract a mate. A single female can produce over a million eggs. It takes between two and three days for the eggs to hatch into the larval young, and between three and four years for the young to reach sexual maturity. Animals Network. Red Angus. But, did you know that they are also iconic because they are one of the fastest swimmers in the ocean? When researchers examined the sailfish swimming out in the ocean, they discovered that they have the unique ability to retract and deploy their sail and other fins.
Furthermore, they saw that when swimming at top speeds, swordfish retract their sail, and when the fish are hunting prey, they deploy it. How does retracting the sail help them swim fast, and how does deploying the sail help them hunt? When it comes to swimming fast, the answer may have to do with drag.
Due to their hydrodynamic characteristics , sailfish have a very low drag coefficient, which is the quantity used to describe the resistance of an object moving through fluid. Sailfish have a drag coefficient of 0. They appear to feed mostly in mid-water along the edges of reefs or current eddies.
They eat squid, octopus, mackerels, tunas, needlefish, flying fish, mullet and other small fishes. Sailfish are a blend of marine savagery and efficiency in the way they hunt. Sailfish ball their bait schools. One will work the surface by jumping anti-clockwise in a tight circle with sail and fins folded. This apparently random free-jumping is part of an organized ruthless, cooperative feeding pattern.
This surface jumping helps ball up the baitfish into tight masses. Other sailfish in the school will circle below the surface at various levels with dorsal fins and pelvic fins fully extended to look as big as possible to assist in rounding up the bait. Then they gently take their prey from the outside of the column of bait in their circling.
Its fighting ability and spectacular aerial acrobatics, along with fast surface runs, have established its reputation as a top sport fish, but it tires quickly and is considered a light tackle species.
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