Mustelidae & Mephitidae
The stinky mammals: Mustelidae (the weasel family) and Mephitidae (the skunk family) both have the power to secrete an intense foul odor. This station contains information about pelts, skulls, and warning coloration. Focus can also be placed on the useful adaptation of the Mustelidae body plan. Skulls can be paired with corresponding pelts in this station.
Pelts of Mustelidae & Mephitidae
The pelts are very fragile! Please handle them gently and treat them with respect.

Start with one pelt and talk about the types of fur and what makes a mammal a mammal. Focus on adaptations of the pelt, and encourage observations from your students. When you bring out the next pelt, compare its adaptations with the previous pelt. Relate those adaptations to habitat and niche.

Mammals
What makes a mammal a mammal? All mammals have fur all over their bodies. Even humans, look closely! Mammals give birth to live young, and nurse their young in infancy. Mammals are warm blooded.


River Otter
Feel the fur. Is this a water creature or a land creature? Look at the claws. Is it a carnivore or an herbivore? River otters hunt for their food in the water. They are long and skinny like a weasel, and their torpedo shape and muscular tail helps them to swim fast.


Weasel and Ermine
Look at the shape of the weasel and the ermine. Can you tell what animal they are closely related to? (they are related to the river otter) The ermine is white in winter and brown in summer. Why do you think the ermine changes color with the seasons? What is the black tip on the ermine's tail for? (it looks like the black nose and will confuse predators)
Striped Skunk and Spotted Skunk
The skunks have a different type of coloration than camouflage. What does this coloration do? (acts as a warning for other animals) How do other animals know that black and white means danger? (they have to learn through experience; an animal has to be sprayed once by a skunk before it knows that a black and white animal is one to stay away from) What are the skunk's claws good for? (digging)
The Striped Skunk and Spotted Skunk pelts are examples of warning coloration. The colors tell the predator to avoid the animal, because danger is involved. But how does the predator know what the colors mean? It has to learn about it.

Below is a series of photographs, documenting a Blue Jay's learning process as it eats a Monarch Butterfly for the first time.
Picture
The Blue Jay eats the butterfly, realizes something is wrong, then vomits. When this same bird was offered a second Monarch Butterfly, the bird refused to eat it. The Blue Jay learned from its mistake.
Next are some animals with warning coloration that most 6th graders have either experienced personally, or they have been near someone who has.
Picture
Black and Yellow Stripes means "I will sting you, stay away!" The last photograph in the series is an example of mimcry. The 5th bug is actually a fly, and has no stinger. If an animal has encountered one of the others first and learned about warning coloration, then it is likely to avoid the last one. Both the striped skunk and the spotted skunk are capable of spraying.
Skulls

The skulls are very fragile! Please handle them gently and treat them with respect. To avoid damaging the skulls, only place them on the rug or the fleece bag. Open your field notebook to the skulls page.

Look at the skull in front of you. What size is it? What general shape is it? Use your hands to sculpt the air and show what size you think the whole animal is. Compare your skull to your neighbors and make some observations about the similarities and differences.


Nose

Look into the nose of your skull. The more bony surface area there is inside the nose, the better the animal can smell. How does this compare with a human nose?
Teeth

Look at the teeth. Are there different types of teeth? Examine the shapes of the teeth. Use your tongue to find similarly shaped teeth in your own mouth.

Can you tell what the animal eats by what kind of teeth it has? Sharper teeth are used for cutting and tearing, flatter teeth are used for grinding and chewing. What happens if an animal with sharp teeth uses its teeth for grinding or chewing? (Domestic dogs are an example of this, their sharp teeth become dull from eating crunchy dog food. Puppies have not eaten as much so their teeth are much sharper).

Herbivores eat plants, carnivores eat meat, and omnivores eat both plants and meat. Which kind of animal is your skull?

The long sharp teeth are called canines. The teeth between the canines are called incisors. The teeth behind the canines (toward the back of the mouth) are the premolars and molars.

Count each type of tooth on your skull. Record your observations in your field notebook. Does your skull have any specialized teeth (such as really long incisors)? What could these teeth be used for? What happens if these teeth break or wear down? (Rodent teeth grow throughout their lifetime. They must chew on hard objects to wear their teeth down and keep them short).




Eyes

Find the eye sockets on your skull. Put your fingers through the back of the skull into the eye sockets to see which direction the eyes point. Do they point forward or to the sides? Record your observations in your field notebook.

What kinds of animals would want to see straight ahead? Why? Animals who hunt other animals (predators) need to focus on the prey that is in front of them.

This kind of vision is called binocular vision. Hold your hands up to your eyes like a pair of binoculars. Both eyes see the same thing from a slightly different perspective. This makes it easy to tell how far away something is.

What kinds of animals would want to see all around? Why? Animals who are hunted by other animals (prey) need to be aware of what is going on around them.

This is called monocular vision. Hold your hands up like binoculars again, but this time cross your arms. Each eye is seeing a different image. This makes it easy to see more of what is going on, but harder to tell how far away something is.

Hold your arms outstretched in front of you. With your index fingers extended and one eye closed, bring your fingers together and try to touch them to each other. Using one eye to view an image, distance is hard to gauge.





Muscles

The more surface area there is on the skull, the more places there are for muscles to attach. Is there a ridge along the top of your skull? This is called the saggital crest. The saggital crest is where the jaw muscles attach, the larger the crest, the stronger the jaw.

Feel the top of your own head. Do you have a large saggital crest? Why not? Now hold your hands on the sides of your head, just above your ears and make some chewing motions. What do you notice?

What kinds of animals would need a strong jaw? Why?

Look carefully at your skull, and compare it to the skull plates in the field guide. Can you tell which species it is? Read about your animal and fill in the information on the skulls page of your field notebook.
Ways to demonstrate depth perception

When you use two eyes to view the same object at the same time, you can tell how far away the object is. This is called "depth perception." Depth perception is useful for animals who hunt.

As humans, we are so used to processing this kind of information instantaneously that we take this skill for granted. Show your students what it is like to only use one eye - or what it is like not to have depth perception.

The finger method - Hold your arms straight out to the sides and point your index finger forward on each hand. Now close one eye. Bring your arms forward and try to make your two index fingertips touch. With one eye closed, it can be difficult to be accurate.
The shrinking hand - Hold your hands side by side a couple of feet in front of your face. Close one eye and slowly move one hand closer or farther away. The hand will look like it's growing or shrinking, but won't really look like it is a different distance from your face.

Playing catch - Find the depth-perception ball in the skulls box. Play a few rounds of a relaxed game of underhand catch with a student. Throw the ball back and forth enough times that the student can consistently catch the ball.

Now have the student close one eye. This time when you throw the ball, don't throw it to the student, just throw it straight up in the air and catch it yourself. The student will try to catch the ball, even though it is nowhere near them. This demonstration only works once, even though many students will want to try it.