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Swimming & Locomotion. Major types of locomotion in fishes. Walking frogfishes Crawling sea robins Swimming most fishes. Antennariidae warty frogfish Antennarius maculatus. The swimming mechanism. Muscles Propulsive waves. Swimming modes. Body musculature. Fin musculature.
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Major types of locomotion in fishes • Walking • frogfishes • Crawling • sea robins • Swimming • most fishes
Antennariidae warty frogfish Antennarius maculatus
The swimming mechanism • Muscles • Propulsive waves
Swimming modes Body musculature Fin musculature
Swimming modes
Swimming examples Thunniform – Carangiform swimming Labriform swimming
Red Epiaxial or dorsal muscles hypaxial or ventral muscles
Distribution of red muscle Bluefin tuna Ectotherm fishes Red muscle Mako shark Skipjack tuna
Propulsive wave • Progressive tailward passage • Push force • Reactive force • Forward thrust component • Lift or slippage component P T R L
Swimming Forces Thrust - Drag Gravity - Lift + Buoyancy
Lift Force • Static lift • Swim bladder • Lipids / Oils • Dynamic Lift • Pectoral fin rotation • Pectoral hydrofoil shape
Drag forces I • Frictional or Viscous Drag • Boundary layer: non-moving water layer that creates friction with surrounding water • Not speed related • To reduce frictional drag: • Mucous • Reduction surface area • Ctenoid scales • Placoid scales
Ctenoid scales Placoid scales
Drag forces II • Pressure or Inertial Drag • Caused by pressure differences • Drag increases with speed • To reduce pressure drag: • Streamline shape • Width-length ratio = 0.25 • Thickest cross-section 2/5 from mouth • Long and narrow wing-like pectoral fins for lift • Body depressions for retracting paired & median fins
Caudal fin shapes high aspect ratio (thunniform swimming) Scombridae Bigeye tuna Thunnus obesus
Caudal fin shapes high/medium aspect ratio (carangiform swimming) Carangidae Jacks Caranx melampygus
Caudal fin shapes low aspect ratio (subcarangiform swimming) Serranidae Nassau grouper Epinephelus striatus
Caudal fin shapes low aspect ratio (subcarangiform swimming) Esocidae Northern pike Esox lucius