In a recent video, we dissected a roast chicken, seeing how the muscles connected to bones to power its wings. This time, we are going to explore a very different arrangement for flight by examining the flight of insects. To try this, you will need: - 2 popsicle sticks or tongue depressors - a hollow, rubber ball - a sharp knife - an adult to use the shape knife (Adults are easier to bandage if they cut themselves.)
Lets start by thinking about bird wings. As we saw in the Bird Bones video, they are made up of several bones, connected at joints, and powered by muscles. An insect's wings are very different. Each wing is all one piece, made of chiton, the same substance that makes its exoskeleton. The wings do not have any joints or muscles. So how do they move?
We can see that by constructing a model, a representation of the insect that will help us understand what is happening. Sometimes scientists use computer models, developing computer programs to simulate a specific event. Other times they construct models from materials to allow them to test ideas. That is what we will do. You need a rubber ball that is hollow, not solid rubber. You can find these in the toy department in many stores. Pick a point on the ball and carefully use the knife to make a cut that is about as long as your popsicle stick is wide. Carefully, insert the end of a popsicle stick into the cut.
Looking at the ball, imagine the face of a clock. Turn the ball until the stick is about at 2:00 on the imaginary clock face. Then make a mark on the ball at about the 10:00 point. Make another cut there, and insert the other stick. Your model butterfly is now complete.
The ball represents the body of the insect. Instead of having muscles attached directly to their wings, most insects move their wings by changing the shape of their bodies. Muscles attach to the top and bottom of the body. Contracting those muscles flattens the body, causing the wings to move up. You can see that by squeezing the ball from top to bottom.
By relaxing those muscles and contracting others, the body changes shape again, moving the wings downwards. You can see that relaxing the hand that is squeezing top to bottom, and instead squeezing the ball from side to side. As the insect flies, its body is flexed by muscles, causing the wings to move up and down. By controlling how much each set of muscles contracts, the insect can change the movement of its wings to control its flight.

This method of flight is used by most insects, including bees, wasps, flies, butterflies, and moths. There are a few insects, most notably Dragonflies and Damselflies, that do have muscles attached to the base of their wings. This lets them control each wing independently, making them very agile fliers.

Last week's activity may have left some of you feeling a bit nervous about how many spiders there are in your front lawn. I don't want you to be afraid to walk on the grass, so lets take a closer look at these amazing, eight legged creatures.

This experiment is Subscriber Only content.

Subscribe Now, and get full access to this experiment, and hundreds of other experiments and videos.

I thought this week we would do something on judging distances. If you look at the faces of different animals, you will find that their eyes are placed differently. Some have both eyes in the front of their face, like ours. Others have their eyes on the sides of their heads. Why? We can do an experiment to learn at least one reason for this.

This experiment is Subscriber Only content.

Subscribe Now, and get full access to this experiment, and hundreds of other experiments and videos.

This week's experiment comes from a recent event in the science news. Researches have discovered that cats drink in a very different way from dogs and other mammals. To explore this, you will need:

- a glass of water
- your fingers
- quick reflexes

Lets start by looking at how other mammals drink. Many of them drink in the same way we do, by creating an area of low pressure inside their mouth. This lets atmospheric pressure push the water into their mouth, just as it does when you use a drinking straw or take a sip of water.

Some other mammals, such as dogs, use a different method. They curl their tongues into a spoon shape, and use it to scoop water up into their mouths.

We had always assumed that cats lapped water in the same way, but recent studies show that they use a different method. Instead of scooping the water up, the cat extends her tongue until it just touches the surface of the water. Then she pulls her tongue quickly back into her mouth. Adhesion and surface tension cause some of the water be pulled upwards, and by quickly closing her lips, the cats get a drink.

Cool, right? Want to see how it works? Place the glass of water on the table in front of you. Use the index finger of one hand to simulate a cat's tongue. You will move that finger quickly up and down, just touching the surface of the water. I found it useful to imagine I was tapping my finger quickly on a table top. As you do that, look closely to see that some of the water is being pulled upwards by the movement of your finger.

Next, use the thumb and forefinger of your other hand to simulate the cat's lips. Place your forefinger and thumb on either side of the finger that is tapping the water. As you pull your finger upwards, move the finger and thumb of the other hand together quickly, trying to catch the drops of water that follow your finger upwards. If you are fast enough, your finger and thumb will get quite wet, indicating that you would be satisfying your thirst if you were a cat.

Timing is very important, and it varies with size. Scientists calculated that larger cats would have to lap slower to be most effective, and observation of lions, tigers, and other large cats confirmed that they used the same method, and that they did lap more slowly.

I always enjoy new discoveries that have been sitting there, right under our noses, or in this case, right under out cats' noses. Scientists are already studying this in hopes of developing new ways for dealing with oil spills and delicate handling of other liquids.

Have a wonder-filled week.

Today was a wonderful day! We went to the Everglades and saw lots of wildlife. Part of the fun of traveling is getting to play tourist, and National Parks are some of our favorite tourist stops.

It was dark by the time we left the Everglades and on the way out, we were watching very carefully in hopes of spotting a Florida panther. We did not see one, but it did give me the idea for which experiment to do this week. Have you ever seen the glow of an animal's eyes reflecting the headlights on a car or the flashlight you are holding? If not, you can try it. You will need:

This experiment is Subscriber Only content.

Subscribe Now, and get full access to this experiment, and hundreds of other experiments and videos.

How long can you smell something before the scent vanishes?

This project has Science Fair potential

Your $20/year subscription helps cover the costs of producing new videos, writing curriculum units, site development, and hosting. Without that support, this site would not be possible.

If you are already a subscriber, and having problems logging in, please check the Support Page.

If you are not yet a subscriber, please check out the Free Stuff page, and Subscribe Now.

How do plants move water and food without a heart for a pump?

Your $20/year subscription helps cover the costs of producing new videos, writing curriculum units, site development, and hosting. Without that support, this site would not be possible.

If you are already a subscriber, and having problems logging in, please check the Support Page.

If you are not yet a subscriber, please check out the Free Stuff page, and Subscribe Now.

Your $20/year subscription helps cover the costs of producing new videos, writing curriculum units, site development, and hosting. Without that support, this site would not be possible.

If you are already a subscriber, and having problems logging in, please check the Support Page.

If you are not yet a subscriber, please check out the Free Stuff page, and Subscribe Now.

Last week, we started talking about genetics and earlobes. This time, we will continue exploring dominant and recessive traits.

IMPORTANT! As I said last week, if your results cause you to think that you are adopted, don't panic. Scientists are learning new things about genetics every day, and the more we learn; the more complex it gets. We THINK that these traits are controlled by a single gene, but future studies may change that.

We looked at inheritance of earlobes, and saw that free earlobes is a dominant trait, and attached earlobes is a recessive trait. Now we will explore and easier way to look at how these traits are inherited, using something called a Punnett square.

To make a Punnett square, start by drawing a Tic-Tac-Toe board.

In the left hand column, we will put the possible genes that an offspring could get from its father. We will stick with the same symbols that we used last week, with "E" for free lobes and "e" for attached lobes. If your father has attached earlobes, which is recessive, then he has two recessive genes (ee), so you would put an "e" in both of those boxes. If your father has free earlobes, then it could either he might have two "E"s or he might have one of each, "Ee". To find out which could take some research on his parents, and possibly their parents, etc. For now, lets say that he has one of each, "Ee". We put an "E" in the middle box on the left side, and an "e" in the bottom box on the left side.

Then, across the top, we will put the possible genes that an offspring could get from its mother. For this example, we will let the mother also have "Ee", which means that while she has free earlobes, she also carries the recessive gene for attached lobes. We put her genes across the top.

Now comes the important part for the science of genetics. We fill in the other blocks by combining the letter at the top of the column, and the letter at the left of the row. For the center box, the letter at the top is an "E", and the letter at the left is an "E", so in that box, we would write "EE".

Then we do the same thing for the other boxes.

This shows us the four possible combinations that each offspring could have.

There is one box with "EE", so there is a 25% chance (one in four) that each offspring will get "EE", which means two dominant genes. That child will have free earlobes.

There are two boxes with "Ee" which means that there is a 50% chance (two 25%s combined) that the child will get "Ee", one dominant gene and one recessive gene. That child will have free earlobes, but will carry the gene for attached earlobes, just like her parents.

There is also one box with "ee", so there is a 25% chance that the offspring will get "ee". That child will have attached earlobes, even though his parents both have free earlobes.

Once you get a grasp on that idea, try some other combinations. What if the father had "ee" and the mother had "EE"? What if the father had "ee" and the mother had "Ee"?

Now, don't confuse % chance with actual percentages. In the example with the boxes above, there was only a 25% chance of the child having attached earlobes, "ee". If the parents had four children, they might all have attached earlobes, or they might all have free earlobes.

Think of it like flipping a coin. When you flip the coin, there is a 50/50 chance of getting heads or tails. Now, what if you flipped the coin five times and each time it came up heads. What is the chance that your next flip will be heads? 50%. Each flip has a 50% chance of being heads. The same is true of genetics. If there is a 25% chance that offspring will have attached lobes that does not mean that if there are four children, only one can have attached lobes. It means that each has a 25% chance of having them.

There are several other traits that seem to be controlled by a single gene, and you can make Punnett squares for them too. Some that you might try include:

Hairline: Having a "widow's peak" is dominant, and a straight hairline is recessive.
Dimples: Having dimples is dominant.
Hitchhiker's thumb: Open your hand as wide as you can. If your thumb bends backwards that is hitchhiker's thumb, which is recessive. Straight thumbs are dominant.
Cleft chin: Having a cleft chin is dominant.

One last thought on the subject. Remember that we are constantly learning more and more about genetics. Each of these may be found to be controlled by more than one gene, so don't panic if the results don't match reality. As long as you have the "I love ice cream" gene, everything will be OK.

Have a wonder-filled week.

How do plants spread their seeds to new areas?

Your $20/year subscription helps cover the costs of producing new videos, writing curriculum units, site development, and hosting. Without that support, this site would not be possible.

If you are already a subscriber, and having problems logging in, please check the Support Page.

If you are not yet a subscriber, please check out the Free Stuff page, and Subscribe Now.