Fish Anatomy and Physiology

Fish locomotion

Types of Fins The source of propulsion for virtually all fish comes from: Undulation of the body Paired Fins: Pectoral Pelvic Unpaired Fins: Caudal Dorsal Anal A combination of the above

Anguilliform swimming (Undulation)

Dorsal & Anal Fin Propulsion

Anal Fin Propulsion Black ghost knifefish

Pectoral Fin Propulsion

Dorsal fin                                                              Bowfin Sea horse Knifefish

Pectoral Fin Frogfish

Walking catfish              

Mudskipper

Hydrodynamics: Effects of shape on drag Disk Sphere teardrop Mechanisms for reducing resistance (air more dense than water, so there is more resistance)             a. types of resistance                 (1) frictional resistance -- proportional to the amount of surface area in contact with the water (least for a sphere -- least SA/V);                 (2) form resistance -- drag while moving is proportional to the cross-sectional area of the object in contact with the water                     (a) big for a sphere                     (b) smaller if long and thin                 (3) Induced drag – turbulence (vs. smooth laminar flow) creates vortices (eddies) and increases the drag             b. Generally advantageous to maximize laminar flow – smooth or absent scales; covered with slime --                     streamlined body surface             c. BUT, if the animal is large and fast, you can’t prevent turbulent flow – have controlled turbulence                 (1) swordfish:  rough sandpaper-like skin on their sword                 (2) tunas: scales behind the head (corselet)             d. most streamlined bodies have a teardrop shape balance between frictional resistance, form resistance and induced drag -                 (1) gives the lowest resistance for the largest volume                 (2) ratio of largest diameter to length is about 0.22 (whales, dolphins and tunas)             e. Fast swimmers outperform subs and torpedos by behavioral mechanisms teardrop Laminar flow and turbulence

Slowest Fish Ewa Blenny 0.5 mph

Fastest Fish                                                      Blue-fin tuna 43.4 mph leaping Sailfin 68 mph, leaping

Tuna- long distance swimmer Snapper- short bursts

Respiration Gills

               

Countercurrent Exchange                

Respiratory and Circulatory System

Ram Jet Ventilation

Buccal Pump Ventilation

Feeding Behavior Suction feeding Slingjaw wrasse

Sensory system Lateral Line Inside lateral line canal

Fish adaptation to buoyancy in water Swim bladder Large liver and heterocercal tail lipid reserves in fish without swim bladders (e.g., sharks, mackerels, bluefish, and bonito)             a. distributed throughout the body             b. localized                 (1) pelagic sharks  -- enlarged liver with lipids Buoyancy Compensator Device (BCD)

Swim Bladder Physostomous Gas Bladder air PHYSOSTOME Chum salmon

Swim Bladder Physoclist gas bladder Rete mirable

No Swim Bladder Missing in fish that swim fast or change depth rapidly (Tuna) Benthic fish (blennies, hawkfish, stonefish…) Sharks, skates, rays Deep water fish