Marine Biology Lab: Fish Dissection

Name ___________________________
Date _________ Period 1 2 3 4 5 6
14. Use forceps to remove a few scales from your fish. Observe the scales under the
Fig 3
magnifying glass or microscope. Sketch a scale on Fig 3.
Internal Anatomy
15. Insert the tip of the scissors in the anus and cut toward the head, between the pelvic fins
and just past the pectoral fins. Cut only through the skin, careful not cut any organs.
Continue cutting through skin and muscle as in Fig 4.
16. Carefully lift off the flap of skin and muscle to expose the internal organs in the body cavity.
17. Locate the cream colored liver in the front of the body cavity. Also locate the gall bladder between the
lobes of the liver. Label these on Fig 5.
18. Remove the gall bladder & liver to observe the short esophagus attached to the stomach. Fig 4: Cut lines
Label the stomach on Fig 5.
19. At the posterior end of the stomach are the coiled intestines. Label these on Fig 5.
20. Find the small reddish brown spleen near the stomach and label this on Fig 5.
21. Below the operculum, are the bony gill rakers. Locate these and them label them on Fig 5.
22. In front of the liver & behind the gill rakers is the pericardial cavity containing the heart. The heart of a
fish only has 2 chambers --- an atrium & and a ventricle. Locate the heart & label it on Fig 5.
23. In the upper part of the body cavity, below the lateral line is the swim bladder. This sac has a thin wall.
Label the swim bladder on Fig 5.
Figure 5: Internal Perch Anatomy
24. Below the swim bladder are the gonads
(testes or ovaries). Label them on Fig 5.
25. Find the two long, dark kidneys in the
posterior end. Label the kidneys in Fig 5
26. Wastes exit the body through the anus
located on the ventral side of the perch.
Label the anus on Fig 5.
Questions:
1. Are both jaws of the fish equally
movable? Explain your answer.
2. Does the perch have eyelids?
3. How many gills are located on each side of the perch? What covering protects them?
4. The tail end has no organs; it’s all muscle. Why do you think that is?
5. Explain how gas exchange occurs at the gills.
6. Which fin was the largest? What other difference do you notice in this fin compared to the others?
7. What is the function of the lateral line?
8. Describe how the scales are arranged on the trunk & tail of your fish.
9. What is the function of the swim bladder? Explain how it works.
To learn more, check out:
http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9b/Perch_Mount_1/perch_mount_1.htm