This document discusses the diversity of body shapes and tail fin morphologies in fish and how these adaptations help fish survive in their environments. It describes the main body shapes as fusiform for fast open water swimmers, compressiform for quick bursts of speed, and depressiform for bottom-dwelling fish. It also outlines different tail fin shapes including homocercal forms that are rounded, truncate, forked, or lunate and the heterocercal tail of sharks, and explains how each tail type relates to the fish's swimming ability, speed, maneuverability and environment.

1. Fish Morphology
Great diversity
exists among
fishes body
types and in
adaptations
they have that
help them
survive in their
environment

2. Body Shape - Fusiform
• Streamlined, torpedo-
shaped
• Fast open water swimmers
• Predators
• Move tail side to side
• Ex: Tuna, Swordfish, Shark,
Striped Bass, Salmon

3. Fusiform
Elfin Cove, AlaskaElfin Cove, Alaska
Orient Point, New YorkOrient Point, New York

4. 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

5. 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

6. Elfin Cove, AlaskaElfin Cove, Alaska Montauk, New YorkMontauk, New York
Check out tail shape Check out tail shape
Depressiform

7. Body Shape – Filiform (Attenuated)
• Elongated shape
• Slow
• Live soft mud, sand, or
under rocks
• Slither like a snake
• Ex: Eels, Sand Lance
Side
view

8. Caudal Fin Shape
• Caudal Fin = Tail
• Homocercal = symmetrical
• Heterocercal = asymmetrical

9. 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

10. 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)

11. 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

12. Huntington, New
York
Huntington, New
York
Smithtown, New YorkSmithtown, New York
Homocercal-
Forked

13. Tail Shape – Homocercal- Lunate
• Half-moon shaped
• Fast moving oceanic
swimmers
• Less drag, great acceleration,
reduced maneuverability
• Ex: Tuna, Swordfish

14. Tail Shape – Heterocercal
• Medium speed
• Asymmetrical – top longer
than bottom
• No air bladder, so tail provides
lift
• Reduced maneuverability
• Ex: Many sharks