Product: Fisheries Science and the Striped Bass Fish Dissection

Transcription

1 Product: Fisheries Science and the Striped Bass Fish Dissection Student Name: Now that you have learned about some common practices in fisheries science, here is another hands-on opportunity for you to show what you know by investigating the internal and external anatomy of a fish species. In this activity, you will dissect a fish and identify and describe some of its special characteristics. Objective: To observe and study the biology of a common sport fish of the Chesapeake Bay and to describe the general characteristics of fish as vertebrate organisms. Materials: Fish either frozen specimen or preserved specimen Dissection pan or tub Newspapers and paper towels Scissors, Scalpel, Dissection pins and probes Textbooks, lab manuals or guides with fish diagrams Safety Remember to follow your lab safety techniques (according to your school s safety contract). Dispose of the specimen properly and wash your hands and materials after you complete your dissection. Procedure: Obtain a fresh fish from a local grocery store or a seafood store. Thaw out your specimen and place it in a dissection pan or tub. Remember to use your lab safety techniques and follow the directions below to complete your dissection. You can also obtain additional guides or lab manuals from your teacher to help in your identification of fish anatomy. If you use a preserved fish for your dissection, you may want to wear disposable gloves during the dissection. Fisheries Science and the Striped Bass Mathematics & Science Center 1

2 A. External Anatomy Look closely at your fish and identify the following structures: Dorsal fin Caudal fin Pelvic fin Pectoral fin Fin spines Lateral line Dorsal side Ventral side Eyes Operculum Gills Nostrils Upper & lower jaw Mouth Teeth Use the diagram of external anatomy to help you find these structures. Notice the color patterns on your fish. Notice the shape of the fish and how it is built for movement in the water. Feel the fish s skin and scales. Draw a picture of the fish on your lab report form. Identify the names and functions of the structures you identify. Identify the dorsal and ventral sides of the fish. Fish Dissection: Diagram of External Anatomy Fisheries Science and the Striped Bass Mathematics & Science Center 2

3 B. Internal Anatomy Carefully lift up and then cut away the operculum to expose the gills. Note the gill rakers, the bony projections along the inside curve of the gill arches. Cut the fish open by using scissors or a scalpel, beginning at the anus all the way up to the bottom of the lower jaw. Be careful not to cut any of the internal organs. Examine the internal body cavity of the fish. Note the muscular body wall and the thin transparent membrane that encloses the organs. Now, attempt to locate and identify the following internal organs: esophagus, intestine, stomach, swim bladder, liver, and the kidneys. Also look for fat deposits around the stomach area. You can refer to the diagram of internal fish anatomy below to guide you in your dissection. Fish Dissection: Diagram of Internal Anatomy Draw a picture of the internal anatomy of the fish on your lab report form. Identify the names and functions of the structures you are able to identify. Then answer the analysis questions on your report form following your drawings. Fisheries Science and the Striped Bass Mathematics & Science Center 3

4 Go Further! Attempt to locate the heart. The heart is right behind the head, and near the gills of the fish. You should also be able to find the gall bladder and the caecum (which helps to digest plant material the fish eats). Now attempt to locate the testes or ovaries of your fish and try to determine the sex of your specimen. The male has testes that lie beneath the caecum. The female has a large egg mass and two large nidamental glands (that produce a covering for the eggs). Remove the eye and cut it in half. Identify the transparent lens and the shiny black retina. Finally, see if you can find and remove one of the otoliths of the fish. To do this, you will need to cut the head of the fish off at the beginning of the operculum. Cut straight down, from the dorsal side to the ventral side. This will expose the interior of the fish skull cavity. You should then probe downwards along each side of the brain cavity area with a pair of forceps. The otoliths will be a rock-like piece of bone in this area. Cut to remove Otoliths Dissection of a Croaker Fish Internal Organs of a Large Fish Fisheries Science and the Striped Bass Mathematics & Science Center 4

5 The Lateral Line Cut to Expose Otoliths Bottom Cut to Expose Internal Organs Side View of Internal Organs Fisheries Science and the Striped Bass Mathematics & Science Center 5

6 Fish Dissection Report Form Name Date External Anatomy Internal Anatomy Fisheries Science and the Striped Bass Mathematics & Science Center 6

7 Questions for Analysis 1. Describe how a fish moves in the water. How is its body shaped to perform this function? What special features assist in movement? 2. What special features of the fish show that it is adapted to be a predator? What organisms would you think are the prey of this fish? 3. Another special adaptation of the fish is its swim bladder. What is the function of this organ? What might be the advantages and disadvantages of this special organ? 4. What features of the fish are common to all vertebrate organisms? 5. What did you learn from this dissection that helped you better understand the physical and behavioral needs of this fish as a living organism? Fisheries Science and the Striped Bass Mathematics & Science Center 7