1. Fish Morphology
The morphology of a fish is a result of adaptations to several forces.
Environmental influences cause variations in the general structure of a fish.

2. Pectoral and Pelvic Fins
Pectoral and pelvic fins are paired fins.
Main function: Turning

3. Dorsal and Anal Fins
Main Function: Balance, Prevent pitching and spinning

4. Caudal Fin The caudal fin is a life-style indicator
The aspect ratio of the caudal fin of a species closely correlates with its average level of activity (Pauly 1989).

5. The Aspect ratio (A) of the caudal fin is calculated from:
The Aspect ratio (A) of the caudal fin is calculated from: A = h2 / s where h is the height of the caudal fin and s its surface area
High apsect ratio, like this lunate, is efficient high speed =Cruiser
Low aspect ratio, like this rounded, is good for short bursts of speed.

6. High aspect ratios Low aspect ratios small surface area
move less water
go faster for longer periods of time
think speed boat propeller
Low aspect ratios
large surface area
move more water
use more energy cannot swim long
think paddle boat propeller

7. Heterocercal Caudal Fin
asymmetrical
characteristic of sharks
produces lift in addition to thrust.

8. Body Shape An adaptation to 3 types of drag (resistance)
Frictional drag – due to skin touching water
ideal shape = sphere
Form Drag – due to the amount of water that must be displaced as the fish is moving forward
ideal shape = thin cylinder
Turbulence – uneven pressure due to water traveling around the body
ideal shape = streamline (length is 4.5 > diameter)

9. Frictional drag
due to skin touching water
ideal shape = sphere

10. Form Drag
due to the amount of water that must be displaced as the fish is moving forward (think of a big-rig truck pushing through the wind)
ideal shape = thin cylinder

11. Turbulence uneven pressure due to water traveling around the body
ideal shape = streamline (length is 4.5 > diameter)

12. Fusiform
Combined adaptations for the 3 types of drag

13. Body Form and Function Body Form varies according to lifestyle
Cruising specialists tend to have a fusiform shape

14. Body Form and Function
Maneuvering specialists tend to have a tall and elliptical shape. Good for precise/sharp turns

15. Body Form and Function
Accelerating specialists tend to have thinner longer bodies.

16. Other Forms and functions
Elongated body moved slowly conserves energy
Examples: Gulper Eel and Bristle-mouth Fish
live in the mesopelagic

17. Flat Fish Flat Body allows them to sit on sea floor
examples: Flounder, Halibut, Rays...

18. Finlets
Help to decrease/control turbulence of water riding over dorsal and anal fins
Found on fast cruisers (tuna, sailfish...)