Name(s) _____________________________________________ Period______ Date____________
Fish Dissection
Introduction:
In this lab each student will work with a lab group in order to learn from the dissection of a fish.
Dissection gives the student the opportunity to observe the placement of organs and their relationships
to one another. (Note that this guide was designed to be used with perch. Some anatomical features
may vary from fish to fish.) Before beginning the lab each student should familiarize himself with the
fish. Pictures and diagrams will aid in the completion of this lab dissection. Be thorough and do not
rush through the lab. Read all directions carefully and make all drawings as accurate and neat as
possible.
Materials:
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Preserved fish
hand lens
dissecting tray
dissecting probe and scissors
pre-lab pictures & diagrams
Procedure
A. External Anatomy:
1. Place a preserved fish on a dissecting tray. Sketch the general shape of the fish in Figure 1 below.
TL ________
FL ________
PcL _______
Figure 1: External Anatomy of a _____________________.
Measure the length of the fish. The total length (TL) is measured from the mouth to the end of the tail.
The forked length (FL) is measured from the mouth to the fork of the tail. The precaudal length (PcL)
is measured from the mouth to the caudal peduncle (an indentation somewhere on the tail stalk). List
these in Figure 1.
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A. External Anatomy continued…
2. Locate the head region. Examine the eyes. Are there any eyelids present? _______.
3. Draw the eye in the space below.
4. Draw and label the eye on the external view (Figure 1) of the fish.
5. Examine the two flaps located on either side of the head.
6. What is the name of these flaps? ________________________
7. What is their function? __________________________
8. Draw and label the flaps on the external view (Figure 1) of the fish.
9. Examine the five (5) types of fins.
10. Sketch each fin on the external view (Figure 1) of the fish.
11.. How many fins of each type does this fish have?
Caudal ____ Dorsal _____ Anal _____ Pelvic _____ Pectoral _____
12. Each fin has a purpose or job. From the shape and location of the fins, deduce the purpose of each
of the following fins for your fish.
a). caudal fin_________________
d). anal _________________
b). dorsal fins________________
e). pelvic ________________
c). pectoral fin _______________
13. Locate the lateral line. Using the hand lens or dissecting microscope look at the line and the
surrounding area.
14. Draw the magnified view of the lateral line in the space below.
15. Draw and label the lateral line on the external view (Figure 1) of the fish.
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B. Internal Anatomy:
16. Using your thumb, lift up the edge of the operculum and raise it up as far as you can. Using your
scissors, 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.
17. How many layers do you find? ___________
18. Using your scissors, remove one of these layers. Examine the feathery structure.
19. Examine the gill with a hand lens or dissecting microscope. Draw the gill structure in the space
below.
20. To expose the internal organs you will cut away part of its muscular wall. Grasp your fish, holding
it with your thumb on one side and fingers on the other. Turn your hand upward to expose the
ventral surface. Using your scissors, insert the point into the skin just in front of the anus. Cut
forward to the gills. DO NOT CUT DEEPLY! Be careful not to destroy any of the internal organs,
since they are mostly found in this area. Place your thumb into the open cut area and lift up,
separating the bottom from the top. Using your scissors, cut upward near the anus and the
operculum and form a flap of skin and muscle. Finish cutting along the lateral line and remove the
flap of tissue. See the Figure 2 below.
Figure 2
21. The fish contains a 2 chambered heart. Locate this organ found just behind and below the
gills. Label the parts of the heart below. Label the heart on Figure 3.
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Fish Heart
22. 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.
23. How could this help the fish? _________________________________________________
24. Label the mouth on Figure 3.
25. Label the pharnyx on Figure 3.
26. Label the esophagus on Figure 3.
27. The esophagus leads into the stomach. Cut out the stomach and carefully cut it open using a
scalpel.
28. Draw the inside of the stomach in the space below. Note any contents that you can identify.
29. Label the stomach on Figure 3.
30. Locate the rather large liver located just in front of the stomach.
31. Draw the liver in the space below.
32. Label the liver on Figure 3.
33. Follow the intestine to the anus.
34. Label the intestine and anus on Figure 3.
35. Locate the kidneys, found just below the spinal column. Their main function is to rid the body of
nitrogenous waste.
36. Label the kidneys on Figure 3.
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37. The swim bladder is the last remaining organ to be identified. It is located between the kidneys and
gonads.
38. What is the function of the swim bladder?_____________________________________
39. Label the swim bladder on Figure 3.
Figure 3 Internal View of a Typical Fish
40. Research information & diagrams on the brain, muscles, skeleton, or reproductive tract of
your fish and how to dissect them.
41. Use the information to dissect the part of the fish that you researched. Draw and label it in the
space below.
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Discussion Questions:
1. Compare your dissection notes to those of other lab groups. Using your notes create a table that
compares the fish. Include size, coloration, fin position, and other major anatomical features of
each fish in your table.
2. Using your table, hypothesize the type of habitat in which each fish lives. (i.e open water,
bottom, grass beds, reefs,etc.)
3. Hypothesize what types of food are in the diet of each fish.
4. Which fish is the fastest? slowest? Why do you think so?
5. Which fishes are predators? Prey? Both?
6. What new questions about fish have occurred to you after completing this dissection?
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