Scavengers
Animals that feed on dead and decaying matter. These animals may be carnivores, herbivores, or omnivores, and may engage in scavenging in addition to other eating habits. Scavengers can be mammals, birds, reptiles, arthropods, and more.

This station contains live specimens. Please be careful when handling the live specimens. The Giant Northwest Millipedes in this station like to hide in the soil. As a group, gently sift through the soil until you find a few. There may even be enough of them for every member of your group to hold one. Hold the millipedes over the tub so they don't fall very far if they are accidentally dropped.

Discuss all of the scavengers in the tub and how they differ from one another. Since many arthropods are scavengers, incorporate the arthropods lesson into your discussion. Structure your hike around finding evidence of scavengers and decomposers. Don't forget to stop at the decomposition station on the hike!
Giant Northwest Millipede
Tylobolus deses

The Giant Northwest Millipede is not as common as the Yellow-spotted Millipede (or Clown Millipede). It eats primarily decomposing leaf litter that forms the duff layer of the soil, and excretes rich topsoil.

The name millipede means "thousand-foot," but no millipede has that many legs. The Giant Northwest Millipedes have about 200 legs.

The millipedes in the scavengers station are slow to unroll from their defensive posture, but once they awaken, watching their legs move in a wave-motion can be hypnotic. All of the millipedes in the scavengers station have names that can be shortened to the nickname "milli."
Virginia Opossum
Didelphis virginiana

Opossums are the only marsupials that live in North America. A marsupial is an animal that keeps its babies in a pouch.

Opossums are nocturnal, which means they are active at night. Look at the colors of the opossum's fur. Why are there so many different colors? (just like fabric camouflage, small areas of different colors blend in much better than a large area of the same color)
Insects
• 3 pairs of legs (six total)
• 3 body segments
• 1 or 2 pairs of wings
• One pair of antennae

Insects include beetles, ants, flies, bees, etc. Insects are the most numerous group of animals. There are more species of beetles than all other non-insect animal species combined. Insects have been around for 390 million years. The African Goliath Beetle is the heaviest insect in the world and weighs 100 grams (the same as 33 pennies).


Arachnids
• 4 pairs of legs (eight legs total)
• 2 body segments
• No wings
• No antennae

Spiders inject enzymes into prey that digest the insides. The spider then drinks the liquefied innards through hollow fangs. Arachnids include spiders, ticks, mites, and scorpions. The longest lived spiders are the tarantulas, some live up to 28 years.


Centipedes
• 1 pair of legs per body segment (total of two legs per body segment)
• No wings
• One pair of antennae

Centipedes are carnivorous, they eat smaller insects. Centipedes have a poison gland to kill prey. The longest centipede in the world is the giant scolopenders of South America and Asia, which can reach up to 11 inches.

 

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Millipedes
• 2 pairs of legs per body segment (total of four legs per body segment)
• No wings
• One pair of antennae

Millipedes are herbivores and decomposers. They eat the forest duff layer and put nutrients back in the soil for plants to use and grow. They decompose 90% of the duff layer of soil. Millipedes have stink glands to repel predators and they curl into a tight ball when threatened. The millipede with the most legs lives in California and has 375 pairs of legs, that's 750 total legs!

Crustaceans
• 5 or more pairs of legs (ten or more legs total)
• No wings
• 2 pair of antennae
• Many body segments

Crustaceans have specialized legs for walking, swimming, crushing, and for defense. Crustaceans include crabs, lobsters, barnacles and crayfish. The pill bug, or sow bug (sometimes called the potato bug) is the only land crustacean.
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.