This document discusses fish morphology and body shapes. It describes four main body shapes that fish can have - fusiform for fast-swimming predators, compressiform for quick bursts of speed, depressiform for bottom-dwelling fish, and filiform for elongated shapes. It also discusses caudal fin shapes, noting homocercal fins can be rounded, truncate, forked, or lunate, while heterocercal fins are asymmetrical and aid sharks in swimming. Examples are provided for each body and fin shape type.

1. FISH MORPHOLOGY

2. 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

3. 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

4. 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

5. 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

6. 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

7. CAUDAL FIN SHAPE
•Caudal fin = tail fin
•Homocercal – symmetrical
•Heterocercal - asymmetrical

8. 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

9. 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

10. 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

11. Caudal Fin Shape –
Homocercal - lunate
• Half-moon shaped
• Fast moving, oceanic fish
• Less drag, great acceleration, reduced
maneuverability
• Examples: tuna, swordfish

12. Caudal Fin Shape –
Heterocercal
• Medium speed
• Asymmetrical – top longer than bottom
• Provides lift when no air bladder
• Reduced maneuverability
• Example: many sharks
blue shark