Fish Morphology

Great diversity exists among fishes body types and in adaptations

they have that help them

survive in their environment

Body Shape - Fusiform

• Streamlined, torpedo-shaped

• Fast open water swimmers• Predators• Move tail side to side• Ex: Tuna, Swordfish, Shark,

Striped Bass, Salmon

Fusiform

Elfin Cove, AlaskaElfin Cove, Alaska

Orient Point, New YorkOrient Point, New York

Body Shape - Compressiform

• Compressed from side to side

• Quick bursts of speed over short distances

• Live among plants, move among narrow spaces

• Move tail side to side• Ex: Moonfish, Butterflyfish

Front view

Body Shape - Depressiform

• Flattened top to bottom• Live on the bottom• Predators or scavengers• Flap fins up and down,

swim like a bird• Ex: Halibut, Flounder,

Skates, Rays

Front view

Elfin Cove, AlaskaElfin Cove, Alaska Montauk, New YorkMontauk, New York

Check out tail shape Check out tail shape

Depressiform

Body Shape – Filiform (Attenuated)

• Elongated shape• Slow• Live soft mud, sand, or

under rocks• Slither like a snake• Ex: Eels, Sand Lance

Side view

Caudal Fin Shape

• Caudal Fin = Tail• Homocercal = symmetrical• Heterocercal = asymmetrical

Tail Shape – Homocercal-Rounded

• Large amount of surface area allows sharp turns, quick starts for predator avoidance

• Creates drag, fish tires easily

• Ex: Northern Puffer, Clownfish

Tail Shape – Homocercal-Truncate

• Allows short bursts of speed to escape predators or constant slow swimming

• Less drag than rounded• Bottom dwelling fish• Ex: Killifish, Flounder,

Halibut (see slide 6)

Tail Shape – Homocercal-Forked• Allows constant swimming

over long distances, reduces drag

• Open water swimmers• Don’t need speed for

protection or to catch food

• Ex: Many schooling fish, Menhaden, Striped Bass, Porgies

Huntington, New York

Huntington, New York

Smithtown, New YorkSmithtown, New York

Homocercal-Forked

Tail Shape – Homocercal- Lunate

• Half-moon shaped• Fast moving oceanic

swimmers• Less drag, great acceleration,

reduced maneuverability• Ex: Tuna, Swordfish

Tail Shape – Heterocercal

• Medium speed• Asymmetrical – top longer

than bottom• No air bladder, so tail provides

lift• Reduced maneuverability• Ex: Many sharks