Observing Capillary Circulation in Goldfish Anatomy and Physiology Purpose: To see how capillaries appear and work in a living organism.

Materials: cotton petri dish 2 glass slides goldfish eyedropper pipette microscope beaker Procedure: 1. Gather your materials for your station, including your fish in a beaker.

2. Soak a piece of cotton (enough to wrap around the fish like a blanket) in the water in the beaker with the

fish.

3. Flatten out (unwrap) the piece of soaking wet cotton ball and place it in the bottom of a clean petri dish.

4. Gently remove the goldfish with a clean hand from your beaker, and place it GENTLY onto the wet cotton so

that the gill and head areas (not mouth!) are covered and the tail fin, the caudel fin, is showing.

5. Place the petri dish on the stage of the microscope so that the tail fin is visible under the low power

objective. Examine the goldfish’s tail under low power only. Move the petri dish around until you see blood

moving in the blood vessels.

6. While one-partner views the caudel fin under the microscope, the other partner should be monitoring the

fish’s wellbeing. Using the eyedropper, count, “1, 2, 3, 4, 5…..drip” and place a drop of water on to the

cotton ball above the fish’s gills. This constant adding should help the fish breathe while out of water.

7. Locate a blood vessel in which blood cells are passing in a single file. This is a capillary. Note the direction of

the flow of blood. Follow the capillary in the direction opposite the blood flow to where it joins a slightly

larger vessel (arteriole). Then follow it in the direction of blood flow until it joins a slighter larger vessel

(venule). In your lab notebook, draw and label the different types of blood vessels that you see. Use

arrows to show the direction of the blood flow.

8. If at any time while viewing the capillaries the blood appears to dramatically slow down, return the fish to

the beaker of water to avoid trauma. When finished, clean up your station and return the goldfish alive

and well!

Questions: Answer the following using complete sentences in your lab notebook.

1. Describe the blood cells’ shape and color.

2. What happens at the site of the capillaries?

3. What is the purpose of blood? How is the heart involved?

4. Why might an organism’s heart speed up or slow down during daily life?

5. Do you think the fish’s blood-flow might slow down after being out of water too long? Why or why not?