Oceanography: Yellow Perch (Perca flavescens) Dissection
Introduction
The scientific name for the yellow perch, most often used in dissection, is Perca
flavescens (Perca means "dusky"; flavescens means "becoming gold colored"). The
sides of the yellow perch are golden yellow to brassy green with a white to yellow belly. Yellow perch have many
small teeth, but no large canines.
Part I: Pre-Lab Questions
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Perch belong to what class of fish?
Perch are ray-finned fish. Explain what is meant by “ray-finned”?
Describe the external appearance of a yellow perch.
What is the scientific name of the yellow perch?
Give the function for the swim bladder.
Name two organs that belong to the digestive system of the perch. (Hint: think of what is found in humans!)
Describe the heart of a perch & explain blood flow through this organ.
Where is the lateral line found and what is its function?
What structures will you find on this bony fish that you did not find on the shark?
Part II: External Anatomy
1. Place the perch on a dissecting tray. Examine it externally. Draw a sketch of your perch, labeling the
following features: anal fin, caudal fin, pelvic fin, anterior dorsal fin, posterior dorsal fin, lateral line,
pectoral fin, eye, mouth, operculum, mandible (lower jaw), maxilla (upper jaw).
External Perch Sketch
2. Complete the following table on the fins of the perch.
Name of fin
Spines (yes or
no)
Number of
fins
Location
Anal fin
Dorsal fin
Caudal fin
Pelvic fin
Pectoral fin
3. Examine the two flaps on the side of the head.
a. What is the name of these flaps?
b. What is their function?
c. How do they aid in respiration?
4. With your thumb, lift up the edge of the operculum and raise it up as far as you can. Use your scissors to cut
the operculum off as close to the eye as possible. You have exposed the gills. The gills are layered one on
top of another. Using your probe, carefully lift each of these layers.
a. How many layers do you find?
5. Use forceps to remove a few scales from your fish. Observe the scales under the magnifying glass. Sketch it.
6. Count the growth rings on your scale to tell the age of your fish. (Hint: each
Scale Sketch
ring represents one year's growth.)
7. What is the name of this type of scale?
Part III: Internal Anatomy
1. To expose the internal organs you will cut away part of its muscular wall. Be careful not to cut too deep and
damage internal organs necessary for observation and answering questions. See the figure below for cut
patterns to make.
2. After making the cuts, carefully lift off the flap of skin and muscle to expose the internal organs in the body
cavity.
3. The fish contains a 2 chambered heart. Locate this organ found just behind and below the gills.
1. Part 1 _______________ Function: _________________
2. Part 2 _______________ Function: _________________
4. Sketch the path blood travels in the circulatory system of a fish. Be sure to use the following terms: veins,
arteries, gills, second heart chamber, first heart chamber, oxygenated blood, deoxygenated blood.
Circulatory system sketch
5. Locate the tube-like digestive system. Begin just behind the mouth in the area called the pharynx. This area
leads into the gullet or the opening of the esophagus. This area is very elastic and can stretch when the fish
is alive.
1. How could this elasticity help the fish?
6. The esophagus leads into the stomach. Cut out the stomach and split it open. Describe its contents.
7. Locate the rather large liver located just in front of the stomach.
1. What is the function of the liver?
2. How does the liver of the perch compare with the liver of the dogfish shark?
8. Follow the intestine to the anus.
9. Locate the kidneys, found just below the spinal column. What is the function of the kidneys?
10. Locate the swim bladder between the kidneys and gonads.
Part IV: Post-lab Questions
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Yellow perch practice the reproductive strategy of spawning. Describe this strategy.
Would you classify the strategy of spawning as ovoviviparous? Justify your answer.
Of the four body types of fish discussed in the notes, which would you assign to the perch?
Are both jaws of the perch equally movable? Explain your answer.