Name _________________________________
Date __________________________________
Fish Dissection
Introduction:
Many of the fish's characteristics can give an insight as to how the human organism works. Dissection gives the student the opportunity to observe the placement of organs and their relationships to one another. In order to make this experience a valued learning one, it is important understand that observation will play a key role in this lab. Take your time and do not rush through the lab. Read all directions carefully; and make all your drawings as accurate as possible.
Materials:
 Preserved perch

 hand lens
 slide dissecting tray
 dissecting probe and scissors
 plastic food bag
Procedure:
A. External Anatomy:
1. Place a preserved perch in a dissecting pan. Locate the head region. Examine the eyes. Are there any eyelids present? __________. If they are not present, give a good reason why they are not present.
________________________________________________________________________
___________.
Label the eye on figure 1.

2. Examine the two semicircular flaps located on either side of the head. What is the name of these flaps? ________________________. What is their function in the respiratory process of the fish? ___________
________________________________________________________________________
___________.
Label the flaps on figure 1.
3. Examine the six types of fins. In each box below, draw one of the fish's six types of fins. Draw the anterior dorsal fin in box 1 and proceed in a clockwise direction around the fish. Label each fin on figure 1.
4. Of the above fins, which ones are considered paired? _________________
____________________.
5. Each fin has a purpose or job, what is the purpose of the following fins? a). caudal fin
_______________________________________________________________________ b). dorsal fins____________________________________________________________________
___ c). pectoral fin
______________________________________________________________________
6. Locate the lateral line. Using the hand lens, describe its location and any features that separate it from its surrounding area.
________________________________________________________________________
___________

________________________________________________________________________
___________
Label the lateral line on figure 1.
Figure 1.
B. Internal Anatomy
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.
7. How many layers do you find? ___________
Using your scissors, remove one of these layers. Examine the feathery structure.
8. Draw the gill structure in the space below.
Gill
9. How does the feathery structure of the gills aid in breathing?
________________________________

________________________________________________________________________
__________
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. 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 below.
Figure 2.
10. The fish contains a 2 chambered heart. Locate this organ found just behind and below the gills. Label the heart below and give the function of each part.
Fish Heart
(a) _______________ Function:
________________________________________________________

(b) __________________ Function:
_____________________________________________________
11. Explain the difference in muscular structure of each of the heart's chambers.
____________________
________________________________________________________________________
___________
Label the heart on figure 3.
12. 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 when the fish is alive. What purpose does this characteristic serve?
________________________________________________________________________
__________
13, The esophagus leads into the stomach. Cut out the stomach and split it open.
Examine the lining and describe it.
________________________________________________________________________
_
14. Why do you think the stomach lining is constructed in that way?
____________________________
________________________________________________________________________
__________
15. Locate the rather large liver located just in front of the stomach. What is the function of the liver? ____
________________________________________________________________________
__________
16. Follow the intestine to the anus. What is the function of the intestine?
_________________________
________________________________________________________________________
___________

Label the mouth, pharynx, esophagus, stomach, liver, intestine, and anus on figure 3.
17. Locate the kidneys, found just below the spinal column. Their main function is to rid the body of nitrogenous waste.
Label the kidneys on figure 3.
The swim bladder is the last remaining organ to be identified. It is located between the kidneys and gonads.
18. What is the function of the swim bladder?
______________________________________________
________________________________________________________________________
___________
Label the swim bladder on figure 3.
Figure 3.
19. Extra Credit: Dissect the fish brain, drawing and labeling it in the space below.