Biology and Marine Biology

Mr. Weinkle

Fish Dissection Lab: 800 points

External and Internal Dissections: 400 points

Lab Report: 400 points

READ THIS HANDOUT CAREFULLY, FOLLOW DIRECTIONS.

Purpose: To investigate and explore the anatomy and structure of a vertebrate animal: the fish.

Your task is broken into 3 parts.

First identify, draw and label the fish. 

Completely dissect the animal and to locate each major organ system. These will include muscular, skeletal, circulatory, digestive, excretory and nervous systems.

Your finished lab report will include a careful and detailed description IN WRITING of the animal. Organize your report so that the purpose, materials and procedure are clear. Your conclusions should answer all questions and describe the specific differences and similarities between this animal and the others you’ve examined.

IMPORTANT: Before you can begin, you must read and STUDY the relevant sections in your textbook and any other sources you can use to help prepare you for this dissection.

Procedure:

EXTERNAL OBSERVATIONS: Carefully observe the fish. Describe it in words (color, patterns, size, etc.) and draw it. WRITE notes of scales, fins, mouth, jaws, teeth, color and all other obvious features. Examine a scale under the microscope and draw it. Trace the lateral line from the head to the tail.

INTERNAL: For the internal dissection:

Insert the scissors or scalpel blade shallowly at the anus and cut forward to the head, along the belly.  Do not cut the intestine.

Cut away one side to expose the internal organs. . Identify the heart, liver, intestines, stomach, gall bladder and gas bladder. Locate the kidney just ventral to the spine. Describe what each organ does.

Carefully, remove each organ one at a time from the anus forward towards the head. Be sure to tell which organ system it is a part.

Rinse out the body cavity or use paper towels to blot up excess liquids.

Cut away one of the cheek plates to reveal the gill and gillrakers. Examine the gills under the dissecting microscope.

Fillet one side to reveal the spinal column- note attachment of fins.

Dissect the heart and locate each chamber of the 2-cycle heart (there are four.) Dissect the stomach and examine for contents and structure. 

Dissect the eye. Locate the spherical lens

Dissect the skull and examine the brain and various nerves. Locate the optic, auditory and olfactory nerves leading to the eyes, ears and nose.

Gently, stretch out the intestine and examine.

After completing the internal and external dissections, Dispose of the carcass in the garbage bag provided. One team member should wash and dry all equipment and return it to the teacher. Wash your hands carefully. Be sure to clean all tabletops and wipe them down to avoid contamination.

After cleaning the tables and nearby areas of the classroom, ALL team members should share notes and drawings. Do NOT let anyone take YOUR notes home. You may never see them again.

Conclusion: In what ways is this animal different from the other animals you’ve examined and studied. How is the lens of a fish eye different from the lens in your eye? How are the bones different from your bones? Hypothesize an explanation for these differences.

Compare the structure of this animal with that of the earthworm, crab and other organisms. What is similar, what is different? What evidence of segmentation did you see?