Perch Dissection
Purpose
To learn about the internal and external features of the perch.
Materials
Preserved perch
Hand lens
Dissecting traydissecting probe and scissors
Pre-lab pictures & diagrams
Hand lens
Dissecting traydissecting probe and scissors
Pre-lab pictures & diagrams
Method - Part 1: External anatomy
1. Place a perch on a dissecting tray. Locate the head. Examine the eyes.
2. Are any eyelids present? Yes.
3. Draw the eye.
4. Label the eye on the drawing of the perch.
5. Examine the two flaps on either side of the head. These flaps are the operculum. They cover the gills, which absorb oxygen by filtering water through them. Label these flaps.
6. Examine the 5 types of fins. Label these.
7. How many fins are there of each? Two pectoral, two pelvic, two dorsal, one anal, one caudal.
8. Each fin has a purpose. What are they? Pectoral: Control up and down. Pelvic: Control direction of movement. Dorsal: Sharp turns, keeping upright. Anal: Stabilize movement, aid in sharp tuns.
Caudal: Propel fish foreward.
9. Locate the lateral line. Using a hand lens, examine the line and the surrounding area. Draw and label this line.
Part 2: Internal anatomy - Gills
10. 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. How many layers are there?
11. Using scissors, remove one of these layers. Examine the feathery structure. Draw the gills
12. 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 upwards from the anus towards the operculum. Cut towards the dorsal surface from each end to form a flap of skin and muscle. Finish cutting along the lateral line and remove the flap of tissue.
11. Using scissors, remove one of these layers. Examine the feathery structure. Draw the gills
12. 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 upwards from the anus towards the operculum. Cut towards the dorsal surface from each end to form a flap of skin and muscle. Finish cutting along the lateral line and remove the flap of tissue.
13. The fish contains a 2 chambered heart. Find the organ just behind and below the gills. Label these parts.
14. Part 1 - Atrium. Purpose - To hold blood before it enters the ventricle
Part 2 - Ventricle. Purpose - To push blood out of the heart all over the body
15. 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.
16. This stretchiness could allow the fish to consume things that could be quite large, or consume a large amount at one time.
17. Label the mouth, pharyx, and esophagus.
18. The esophagus leads into the stomach. Cut open and draw the stomach.
19. Locate the rather large liver in front of the stomach. Draw the liver.
20. Follow the intestine to the anus. Locate the kidneys, found just below the spinal column. They are used to rid the body of nitrogenous wastes. Label the intestine, anus, and kidneys.
21. The swim bladder is the last organ to be identified. It is located between the gonads and the kidney. The function of the swim bladder is to control the amount of water in the fish to make it buoyant.
14. Part 1 - Atrium. Purpose - To hold blood before it enters the ventricle
Part 2 - Ventricle. Purpose - To push blood out of the heart all over the body
15. 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.
16. This stretchiness could allow the fish to consume things that could be quite large, or consume a large amount at one time.
17. Label the mouth, pharyx, and esophagus.
18. The esophagus leads into the stomach. Cut open and draw the stomach.
19. Locate the rather large liver in front of the stomach. Draw the liver.
20. Follow the intestine to the anus. Locate the kidneys, found just below the spinal column. They are used to rid the body of nitrogenous wastes. Label the intestine, anus, and kidneys.
21. The swim bladder is the last organ to be identified. It is located between the gonads and the kidney. The function of the swim bladder is to control the amount of water in the fish to make it buoyant.