Objective to Dissect the Perch and Compare Its Anatomy with the Anatomies of Other Forms of Life

Oceans 11 Citadel High School Perch Dissection Lab Booklet *to be used in conjunction with the Modern Biology book and the Perch Dissection Study Guide* Objective – To dissect the perch and compare its anatomy with the anatomies of other forms of life.

Background: The perch belongs to the phylum.

Materials: Preserved Perch Dissection Instruments Hand Lens Dissections Trays Plastic Bag Rubber Gloves (bring your own)

Procedure: Part 1. External Anatomy

1. Gently rinse the preserved perch under tap water and place it in a dissecting tray. Locate the head region. Examine the eyes. 1A Are there any eyelids present? 1B Why or why not? (referring to the eyelids in questions 1A)

2. Examine the two semicircular flaps located on either side of the head. 2A What is the name of these flaps? 2B What is their function in the respiratory process of the fish? Oceans 11 Citadel High School Perch Dissection Lab Booklet *to be used in conjunction with the Modern Biology book and the Perch Dissection Study Guide* 3. Examine the six types of fins. 3A Of all the fins, which are considered paired? 3B Each of the fins has a purpose or job, what is the purpose of the following fins? Caudal fin, Dorsal fin, Pectoral fin.

4. Locate the lateral line. Using the hand lens examine the lateral line more closely. 4A Describe the lateral line and surrounding area in detail.

5. There are two types of fish scales. Cycloid scale – a smooth edged scale and Ctenoid scale – a fluted edged scale. Remove a scale from your fish (not from along the lateral line) and place it on a microscope slide. Remove a second scale, this time remove the scale from the lateral line. 5A Identify and draw both scales. 5B How do the scales differ?

6. Measurement Chart No. Measurement Description 1 Standard length The distance between the most anterior part of the head and the end of the vertebral column. To find the end of the vertebral column bend the tail and a crease indicated the end of the column. 2 Head length From the most anterior part of the head to the posterior edge of the gill cover. 3 Caudal Peduncle The narrowest part of the the caudal peduncle. Depth 4 Eye Width The distance from the anterior margin of the eye to its posterior edge. 5 Pelvic to anal The distance from the base of the pelvic fin to the beginning of fin length the anal fin. 6 Greatest Body The deepest part of the body. (Estimate). Depth Oceans 11 Citadel High School Perch Dissection Lab Booklet *to be used in conjunction with the Modern Biology book and the Perch Dissection Study Guide* Part 2. Internal Anatomy

7. Using your thumb, lift up the edge of the operculum and raise it up as far as you can. Using 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 the other. Using your probe, carefully lift each layer. 7A How many layers do you find? 7B How does the feathery structure of the gills aid in breathing? Oceans 11 Citadel High School Perch Dissection Lab Booklet *to be used in conjunction with the Modern Biology book and the Perch Dissection Study Guide*

8. To expose the internal organs you need to cut away part of the muscular wall. Grasp your fish, holding it with your thumb on one side and fingers on the other. Turn your hand upward to expose th ventral surface. Using 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 figure above. Note – do not discard the flap of skin and muscle as it can be placed over the opening to preserve the fish if the dissection takes an extended period of time.

The fish contains a two chambered heart. Locate this organ just behind and below the gills. 8A Copy and label the diagram of the 2 chambered heart. 8B What is the name and function of both hearts? 8C Explain the differences in muscle structure of each of the heart’s chambers.

9. 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. The esophagus leads to the stomach. Cut out the stomach and split it open. Examine the lining. 9A What purpose does the elastic area serve? 9B Describe the lining of the stomach. 9C Why do you think the stomach lining is constructed in that way? Oceans 11 Citadel High School Perch Dissection Lab Booklet *to be used in conjunction with the Modern Biology book and the Perch Dissection Study Guide*

10. Locate the rather large liver located in front of the stomach. Follow the intestine to the anus. 10A What is the function of the liver? 10B What is the function of the intestine?

11. Locate the kidneys, found just below the spinal column. Their main function is to rid the body of nitrogenous waste.

12. The swim bladder is the remaining organ to be identified. It is located between the kidneys and the gonads. 12A What is the function of the swim bladder