bar.jpg (9876 bytes)

 

Roadkill Museum
Making a Study Skin - Skinning & Stuffing

Lesson Plan by Debolina Dutta


General Information
Objectives
  Lesson Development

Preparation
  Background Information
Procedure
Materials
Possible Extensions

References
Appendices

General Information:

Location: Shaded outdoor area with sitting room and sink. Recommended that you be near drying boxes.

DurationApprox. 1-2 long class periods or after school (4-6 hours)

Grade Level:  8th - Adult
Aligned with the California State Standards under the grades nine through twelve biology/life science section on physiology.

Objectives:

  1. Academic: To learn about the anatomy and physiology of local mammals and birds.
  2. Personal: To feel comfortable working with animals and dissecting. Learning taxidermy, which is a marketable skill.

Lesson Development:

Students will learn the valuable and marketable skill of taxidermy. Organisms are FOUND DEAD, hence preventing killing of animals for dissection. It may take students some time to become comfortable looking and working with dead animals, however, once they are able to do so, students will gain an increased appreciation for the animals' different physiological characteristics allowing it to survive in the local habitat. Students will have an opportunity to observe essential organs, muscle and bone structure, and physiological difference between numerous types of organisms. Critical thinking is developed. Tracking projects can be conducted which, will indicate what is occurring with the local animal's populations. Students will also form an increased awareness of the effects humans have on endemic and exotic animal populations.

Preparation:

1. Obtain a Collector's Permit from California Department of Fish and Game.
2. Have a large freezer to place roadkilled animals.
3. Collect roadkill in a plastic bag and freeze it till it is hard frozen. This serves to kill ticks, mites, bacteria, etc..
4. Take animals to skin out of the freezer the day before skinning, allowing it to thaw.

Background Information:

Students MUST have the maturity to deal with handling dead and often mutilated animals. Students must also treat the animals with respect. They should be able to manage and use sharp objects without hurting themselves or others. Previous biology experience is essential however, if the student has a keen interest in physiology and taxidermy, they should be given the opportunity to make a study skin.

Procedure:

See Appendix 1 for drawings of procedures.

1. Spread each student out so that everyone has enough room for their animals and tools. Take thawed animal out of the bag and measure the animal in millimeters and weigh it in grams. For mammals, make and record the following measurements: 

Total length: Make animal lie straight but do not stretch it. Measure the distance from tip of nose-pad to tip of fleshy part of tail, excluding hairs that project beyond tip.

Tail length: Bend tail up at right-angle with body and measure from bend on back to tip of fleshy part of tail. Exclude hairs that project beyond tip.

Length of right hind foot: With its toes out straight, measure the distance from tip of longest claw to heel.

Height of ear from notch: Insert end of ruler in notch at bottom of ear and measure to tip of ear.

Determine if male or female. You may need to dissect it to find gonads.

Determine by dissecting how many embryos it has.

Weigh the animal.

Date and were the animals was found.

How it was killed.

Who prepared the study skin and today's date.

2. Place the animal on it's back with arms and legs spread out.

3. Cut from the animal's neck to pelvis. Only cut the skin and make sure not to cut into the body wall. Make sure the skin has as little fat and muscle on it as possible. Residual fat and flesh results in future rotting of the skin.

4. Skin the animal by cutting and peeling skin from the body wall around towards the back. Continue this process till skin is fully separated from body wall and fat. Do not cut the head, tail, and wrist joints of arms and legs, yet. Do not cut mammary glands because they are very hard to sew up.

5. Once the skin is freed from the body around the torso, arms, and legs, use the deboning scissors or clippers to cut just above the wrist joints of arms and legs. 

6. Skin as far down the tail as possible, then clip the bone. This is done usually near the base of the tail, since it is difficult to skin the tail.

7. For large or difficult to skin animals, insert the sharp side of the hook below the animal's abdomen. Make sure you do not damage the organs which will be looked at later in the dissection. Place the hook and the gallow holder on the gallow. Hanging the animals makes it much easier to skin them, since gravity helps pulls the skin off. (See Appendix 2)

8. Unlike the rest of the body, while skinning the head, cut as close to the skull as possible so that the eyelids and lips are not cut off.

To skin birds, follow instruction 1-4.

5. Once the skin is freed from the body around the torso, arms, and legs, use the deboning scissors or clippers to cut just above the knee joints of legs. Clip the wing bone at the shoulder joint.

6. Separate the skin from the base of the tail bone. Cut and scrape away as much flesh and fat including the oil gland. *Do not cut beyond the base of the tail and be careful not to loosen or cut off the bases of the tail feathers. 

7. For large birds, insert the sharp side of the hook below the animal's abdomen. Make sure you do not damage the organs which will be looked at later in the dissection. Place the hook and the gallow holder on the gallow.

8. Skinning a bird's head is tricky. Skin just enough around the neck so that you are able to push the skin slowly over neck and skull allowing the skull to be visible and so the skin is inside out. You may need to skin a bit more around the base of the skull to reveal the eyes. Push the skin towards the beak, but keep the skin ON the beak, to free the eyelids and reveal the eyeballs. Be sure not to puncture or cut the eyes. Use forceps to reach beneath the eyeball, grasp the optic nerve (it feels like a cord) and remove the eyeball with out puncturing it. Use Q-tips to get all the brains out of the skull. 

Both mammals and birds:

9. Once the animals is fully skinned, shampoo the inner part of the skin, paws, and fur thoroughly. Wash birds' skull and head areas, as well. This will be their last bath. Remove all stickers and burrs. Place the birds skull back inside the head.

10. Ring the animal out carefully as a person with long hair would rind their hair after a shower. 

11. Place the animal in a large container with about one cup of chinchilla powder. Close the lid and shake vigorously. Place the wet chinchilla powder in a separate container, for use next time when you skin. You can use chinchilla powder repeatedly, for a very long time. Wet chinchilla powder becomes beaded. Repeat the process with dry chinchilla powder till the animal is fully dry (small animals, usually take 3-5 chinchilla powder shakes). Check feathers and fur next to skin to make sure it is completely dry. Dust off the animal. 

12. Generously borax the insides of the animals to prevent future pest invasions. Use extra borax where body wall and fat still are still connected, at wound sites, inside the head, and down tail, arms, and legs. 

13. Straighten the fur and feathers then place the dry animal with its back down. Sew mammal's eyes and mouth shut so that students are not tempted to poke them. Stuff mammal's face by emulating the animals original bone and musculature structure. Look at the skinned animals for reference. Stuff the eye sockets and eyes of birds. 

14. Place a relatively thin layer of batting along the back of the animal, representing back muscles. Use a dowel about the same diameter as the backbone and measure from head to tail. Cut dowel. Cut 2cm - 15cm of wire (depending on the size of the animal). Duct tape the bottom portion of the wire to the tail side of the dowel. Carefully shove the wire into the tail (preferably into the flesh). This will prevent the tail from flopping about and eventually falling off. 

15. For mammals, use a dowel about the same diameter as the arm and leg bones. By inserting the dowel into arms and legs, measure from wrist to central part of body (near upper abdomen). The arms should project straight forward with paws down and the legs should project straight backward with paws up. Cut dowel. Again, cut 1cm - 4cm of wire (depending on the size of the animal). Duct tape the bottom portion of the wire onto the paw side of the dowel. Wrap batting around the dowels so they accurately represent the arm and leg muscles. Carefully shove the wire into the paws (preferably into the flesh). This will prevent the paws from flopping about and eventually falling off.

For birds, tie the wing bones in the center together. The wings should be folded down against the body. You may expand the bird's talons. The feet of the birds are tied together so that they are crossed. 

16. Use long layers of batting to make the body of the animal.

17. Sew animal shut. You may need to use a thimble and even pliers to get the need through tough skinned animals. If the skin is dry, lightly moisten the skin's edges as you sew. Note: Squirrels have very tough skin and bird's skin dries fast.

18. For mammals, pin or nail down the paws and tail to plywood. Remember: The arms should project straight forward with paws down and the legs should project straight backward with paws up. The tail should project straight back. Pin or nail around head to maintain its shape. Place paper or batting in the ears to make them stand up. Make a label with all the recorded measurements taken in step one and tie the label to the right hind leg of the mammal.

For birds, using your hands, comb down the feathers. While it looks unnatural, make the head tilt back and the beak point forward. Wrap the bird in batting. Make a label with all the recorded measurements taken in step one and tie the label to the legs of the bird. 

19. For both mammals and birds, place the animal in the drying box (see Appendix 3) for two weeks so the skin can harden. The box will be stinky, so I recommend keeping it outdoors. When dry, the inner wall of the skin will sound crinkly, like plastic. It is now ready for demonstrations and teaching!

Materials:

Teacher and those collecting the animals must have a scavenger permit obtained from California Department of Fish and Game

30-cm ruler (in millimeters)

weigh scale (in grams)

labels for study skins

gallow for hanging animals (see Appendix 2)

gallow holders (see Appendix 2)

skinning knife (one per person)

deboning scissors -for small animals

large garden clippers - for large animals

rubbing alcohol (to kill smell, germs, and fleas)

rubber gloves

shampoo

chinchilla dust (can purchase from pet store)

borax

assorted sized needles (one needle per person)

heavy duty thread

thimble

pliers

wire coat hangers

wire cutters

duct tape

assorted sized dowels

knife sharpener ("Diamond" brand is recommended)

big containers with lids (i.e. Tupperware)

Q-tips (for birds)

batting - cotton or nylon-polyester(recommended)

large freezer

drying containers or boxes (see Appendix 3)

Recommended Materials to build Animal Taxidermy boxes:

5 - 3/4" plywood
5 - sheets plastic shower wall 
3 - 5/8" plywood
30' - 8" flashing
4 - Heavy duty castors
6 - 3/8" wingnuts
10 - 1x2" x 8'
10 2x2 x8'
3/4" self tapping screws
8 - 6" hanger bolts
2" drywall screws
7 - tubes caulking
1 quart paint (what ever color you want your boxes)
2 gallon deft

Possible Extensions:

Use the body for dissection

Give students a lab practical on major organs, muscle and bone structure, and the eyes.
Have students compare the anatomy of different animals.
Study the animals' different physiological characteristics allowing it to survive in the local habitat.
Develop a detailed hypothesis on why the animal died. Try to answer what it was doing at that location, why it was there at that time of the day, etc..
Make a tracking project on local animal's populations looking at where occurrence of roadkill occurs and which species is most affected by roadkill. 

This can enable students to propose and design corridors for animals.

References:

Dutta, Debolina. Personal Experience. Berkeley, California. 2001

Hall, Raymond E. Collecting and Preparing Study Specimens of Vertebrates. Lawrence, Kansas: Museum of Natural History at The University of Kansas, 1962. 

Smiley, Kimberly. Personal experience. Big Sur, California. 1987-2001.

Appendices:
Appendix 1 - Measuring, Cutting, Skinning, Stuffing & Sewing

Appendix 2 - Gallow and gallow holder

Appendix 3 - drying boxes