Fish: Form and function

An LSU Museum of Natural Science presentation to accompany the activity

Types and Function of finsAll Fish have fins! Each fin shape has a unique shape and

function.

Dorsal- (top fin) Helps keep the fish upright. Also used for sudden direction changes.

Pectoral- These are the pair of side fins that help the fish move in different directions and aids in the ability to swim and steer. Sometimes have spines used for defense.

Dorsal fin

Pectoral fin

Pelvic- Located on the bottom of the fish. Most often used as “brakes”.

Anal- used to stabilize fish

Additional fins:

Adipose- tiny fin between dorsal and caudel fins

Pelvic fin Anal fin

Types and Function of fins

Caudel (Tail) finThis fin is used to propel the fish through the

water, pick up speed, and make turns.• Rounded caudal fin –allows for effective acceleration and

maneuvering but in general is found on fish that do not swim long distances because of large amounts of drag

• Truncated caudal fin – straight tipped tail; allows for quick turns and short burst of speed

• Emarginated caudal fin – has the least amount of drag; fin has two lobes

• Forked caudal fin- 2 lobes, helps reduce turbulance• Lunate caudal fin- tend to be fastest fishes, maintain speeds

Body shapes of FishSagitiform – elongated tubular body layout that is arrow shaped; allows fish to strike quickly. (Example: gar, barracuda) 

Depression – wide, flat body shapes that all fish to rest on the bottom. (Example: flounder)

Body shapes of Fish

Fusiform: streamlined with pointed ends - shaped like a plane; helps to lower frictional resistance, and allows them to move through the water extremely fast.

Compressiform – fish that are laterally compressed; tall, thin body shape that allows fish to enter vertical crevices; allows for quick bursts of speed and quick turns.

Anguilliform – fish that are long and skinny; these fish slither like snakes; allows them to maneuver into narrow openings and resist the force of current.

Globiform – these fish are almost round or globe-shaped.

Body shapes of Fish

Taeniform – thin ribbon like shape; good for hiding in crevices and cracks.

Lateral line

Pelvic fin

Pectoral finAnal fin

Caudal

2nd dorsal fin

1st dorsal fin

Eye

Operculum

Mouth

Nostril

Gyotaku Gyotaku Japanese art of fish printingJapanese art of fish printing

How it works:1. Paint plastic fish2. Press painted fish onto paper to make

impression. Label parts if desired.

Build you own ‘Franken’fishBuild you own ‘Franken’fish

Materials:• Fish part templates

• Glue

• Crayons

• Construction paper

• Scissors

• Pencil and paper

Purpose: Students will learn about fish anatomy and morphology by building their own fish.

On-line Resources

• Fish anatomy print-outEnchanted learning-

http://www.enchantedlearning.com/subjects/fish/label/labelfish.shtml

• Basic information on fishhttp://www.flmnh.ufl.edu/FISH/Education/Diagrams.htm

• Gyotaku fish