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STUDENT OBJECTIVE

Students observe feeding behavior of Hydra, dissect the digestive and respiratory systems of the fetal pig, study the histology of the small intestine and lung, and observe the anatomy of gills and tracheole systems.

EQUIPMENT	AMOUNT
	(Class of 24 with 8 groups)
Compound microscope Dissecting microscope Spirometers and accessories Aquarium	1/student 1/student 1/group 1/lab
MATERIALS
Slides and coverslips Lens tissue Pasteur pipettes Dissecting trays with wax Dissecting instruments: scissors, forceps, blunt probe,string, razor blades or scalpel Culture dishes Petri dishes filled with paraffin Hand lotion Spot plates for holding and washing Artemia Pins Thread Small bowls Preserved specimens Fetal pigs Storage materials (fiber tags, string, permanent marker, plastic bags, garbage can—20 gal) Prepared slides (may be shared to reduce cost) Hydra, longitudinal section (CBS#30-6052) Mammalian small intestine, cross section (Turtox# Z17.22) Mammalian lung (CBS#31-5654)* Living specimens Hydra (CBS#13-2800) Crayfish Artemia (brine shrimp) or Daphnia cultures Crickets, grasshoppers, or roaches	1 box/lab 8 pkgs/group 1/student 1/student 1/student 1/student 1/student 1 bottle/lab 1/student 1 pkg/lab 1 spool/lab 1/student 1/student 1/lab   1/student 1/student Demonstration   1/student 1/group 1 culture/lab 1/student

*Please refer to the Appendix for name and address of supplier.

SOLUTIONS

India ink
10 mM and 100 mM glutathione (Sigma)*
Carbon dioxide source
Saline (0.7% NaCl)

PREPARATION

Four Weeks before Lab

Fetal pigs, Hydra, Daphnia, crayfish and clam should be ordered for arrival one week prior to lab.

One Week before Lab

1. Stock glutathione preparation:
   a. 100 mM glutathione 3.1 g glutathione/distilled water to make 100 ml
   Dissolve in water.

   b. 10 mM glutathione preparation:
   Take 10 ml of 100 mM glutathione and dilute to 100 ml.

2. An aquarium should be set up to accommodate the crayfish the week before the lab.
3. Make small dissecting dishes by melting household paraffin over boiling water and pouring into petri dishes until half filled. When the wax solidifies, cover and store until needed. These dishes can be reused in later labs.
4. Saline preparation:

NOTES

1. Wax that is pitted with holes in dissection pans can be restored to a smooth finish by fanning the surface with a Bunsen burner.
2. Hand lotion should be provided for the students in exercises that use formalin and require an inordinate amount of hand washing.
3. Any culture dish (soft glass) that has had formalin in it, should be acid washed before any live cultures are added.
4. Place insects in a freezer for 30 to 45 minutes to anesthetize. Alternatively, a stream of carbon dioxide from a gas cylinder directed into a 125 ml flask can be used.

CLASSROOM SUGGESTIONS

1. Students should write their names on fiber tags with soft pencil or permanent ink marker and attach the tags to the back legs of the fetal pigs. Pigs can then be slipped into plastic bags and stored in a sealed plastic garbage pail. Separate pails can be used for different lab sections.
2. Minimum homework would be a short essay comparing incomplete and complete digestive systems or lung and tracheole gas exchange systems.
3. Check out the links for this lab topic at http://auth.mhhe.com/biosci/genbio/dolphin/ You will find useful materials for developing your lab introduction or summary, and in some cases, you may want to tell students to connect to a particular site for further information.

ANSWERS TO CRITICAL THINKING QUESTIONS

1. The extremely long trachea contains a large volume of "dead" air—air that is not involved in gas exchange. To move this large volume of air, the giraffe has oversized lungs.
2. All the structures involved in chewing—the lips, tongue, teeth, hard palate. Muscles responsible for peritalsis—smooth muscle of esophagus, stomach wall, and small intestine.
3. Oxygen is at a greater concentration per unit volume of air compared to water, and because water weighs more than air per unit volume, aquatic animals use more energy to get the same amount of exygen from the surrounding medium than do terrestrial animals. However, air is potentially dangerous to respiratory surfaces because it dries them.

SUPPLEMENTAL MATERIALS