FISH MORPHOLOGY

Fish Morphology• There is a great diversity in

shapes of fishes and their body parts• Shapes of fishes are adaptations

to the species’ environment and/or behaviors

Body Shape - Fusiform• Streamlined, torpedo-shaped• Fast-swimming fish• Predators, live in open water• Move tail side to side• Examples: tuna, swordfish, shark, striped bass

side view front view

Body Shape - Compressiform

• Compressed from side to side• Quick bursts of speed over short distances• Live among plants and move in narrow spaces• Examples: moonfish, angelfish• Move tail side to side

front view

Body Shape - Depressiform

• Flattened top to bottom• Live on bottom• Slow• Flap fins up and down and swim like a bird• Examples: flounder, skates, rays

front view

Body Shape – Filiform (Attenuated)

• Elongated shapes• Live in soft mud, sand or under rocks• Slow• Slither like a snake• Examples: eels, sand lance

side view

CAUDAL FIN SHAPE

•Caudal fin = tail fin•Homocercal – symmetrical•Heterocercal - asymmetrical

Caudal Fin Shape – Homocercal - rounded

• Large amount of surface area allows sharp turns and quick starts – to avoid predators

• Creates drag – fish tires easily• Example: northern puffer, clownfish

Caudal Fin Shape – Homocercal - truncate• Allows short bursts of speed to escape

predator or constant slow swimming• Less drag than rounded• Bottom-dwelling fish• Example: killifish, flounder, sculpin

Caudal Fin Shape – Homocercal - forked• For constant swimming over long distances,

reduces drag• Open water fish• Do not need speed to feed or for protection• Examples: many schooling fish, pilot fish

menhaden

Caudal Fin Shape – Homocercal - lunate

• Half-moon shaped• Fast moving, oceanic fish• Less drag, great acceleration, reduced

maneuverability• Examples: tuna, swordfish

Caudal Fin Shape – Heterocercal

• Medium speed• Asymmetrical – top longer than bottom• Provides lift when no air bladder• Reduced maneuverability• Example: many sharks

blue shark