(Intro)

Well, Squeaks, I think we're almost ready to go.  You know, I think I'm gonna really miss the Fort while we're gone.  Oh, that's a great idea, Squeaks.  If we get homesick, we can always watch our favorite episodes of SciShow Kids and we'll feel like we're right back at home.  What was one of your favorite episodes, Squeaks?  Squeaks says he loves learning about animals, and that cats are just about the cutest animal, so he loved it when we learned all about cats.  Wait a minute, Squeaks, you're a rat.  Aren't you supposed to be afraid of cats?  Ohh, only robot cats.  That makes sense.

What if I told you that there might be a sneaky predator with super powers in your house right now? If you live with one of these, there is! I’m talking about cats! And even if you do have a cat of your own, I bet you don’t know some amazing things about our little furry friends!

For example: did you know that all pet cats are actually related to lions, and other big cats, like tigers, leopards, and jaguars? Wait... this is related to this? Yup! All cats, from the biggest lion to the tiniest of house cats, evolved from the same small, cat-like creature that lived millions of years ago called proailurus [pro-ay-loo-rus] or, “first cat.” Then, after a long time, there came to be two major types of cats. One kind became the bigger cats, like the lion and the tiger. And the other kind became the smaller cats, which includes the ones we keep as pets today.

So, if all big cats and all little cats descended from this same animal from long, long ago, that means they’re related, even if it is only distantly. That’s one big furry family! Now, another cool thing about cats? They have excellent hearing! Lots of animals, including dogs, have better hearing than we do. But cats can hear better than both humans and dogs. Even if your cat just looks like it’s curled up and enjoying a relaxing nap, it’s still extremely aware of its surroundings. Their little ears are super-sensitive, and they’re always listening. Your cat can can hear everything that’s going on around it, from the sound of you listening to music in your bedroom all the way up the stairs, to the sound of birds chirping outside in your neighbor’s yard.

In fact, cats can hear things up to four times farther away than you or I can! And they can not only hear things from far away, they can figure out exactly where those far-away sounds are coming from. So if your cat’s snoozing in the basement, and you open the kitchen cupboard where you keep their favorite treats, they’ll probably come running. But if you open another cabinet in a different part of the kitchen, they’ll probably be able to tell the difference and just keep snoozing!

Thousands of years ago, cats needed this super sense of hearing to help them track down food and to escape predators in the wild. Today, now that they live among humans who help provide for them, they don’t need it quite as much, but it’s always good to know when that treat cupboard opens!

And lastly, our third cool thing about cats: They rule! Well, sort of. Some ancient cultures—like people who lived in Egypt thousands of years ago — treated cats like royalty, almost as if they were kings and queens. Early Egyptians were thought to have had problems with rats in their homes. In order to get rid of the rats, they brought in cats to hunt them. And the people liked the cats so much, they supposedly kept them and treated them extremely well.

Ancient Egyptians even mummified the animals for their journey to the afterlife — just like they did with their human rulers! So, sorry, dogs. It looks like, in ancient Egypt at least, cats ran the show! 

Hmm, what's my favorite episode?  Well, I always liked it when we would learn more about ourselves, like how our bodies work.  Remember when we learned why we shiver, Squeaks?  Or why haircuts don't hurt or why we get mad or scared?  But I think my favorite thing to learn was how our eyes see color.

Today is a really special day for me and Squeaks. We’re eating our favorite colors!

Squeaks really loves the color red, and my favorite is green. So we had some green asparagus for dinner… and check out our dessert! Don’t worry, Squeaks; we’ll eat it soon!

But first, take a look at it! When you see a shiny, red apple… the red you see is just how your brain understands the light bouncing off of it. Your brain gets information about colors from a place at the back of your eye called the retina.

The retina has two kinds of parts inside it that help you see: rods, which are mostly for seeing when it’s dark, and cones, which see colors. When the light in the room shines on the apple, some of it bounces off toward your eyes. And then, the millions of cones in your retina get to work!

There are three types of cones: some cones that look for reddish colors, some that look for greenish colors, and some that look for blueish colors. When you look at a red apple, it makes the cones that like red get excited! [Squeaks gets excited. He really loves that apple!

Jessi holds it up again.] Exactly! When the cones get excited, they send a message to your brain – kind of like a secret code. The code from your cones says, “These are the colors I saw!” Most humans can see all the colors in the rainbow pretty easily, using all three types of cones.

But not everybody has three types of cones to work with! Some people are what we call colorblind. That doesn’t mean they’re blind, and it usually doesn’t mean that they don’t see colors at all, either.

It just means that instead of three kinds of cones, only two kinds work properly. People who are red-green colorblind have a problem with some of their cones – either with the ones that look for red, or the ones that look for green. So to them, red and green don’t look as bright as they do to the rest of us.

Both colors look kind of dull, and kind of similar to each other. So red-green colorblind people have trouble telling red and green apart. The other main type of colorblindness is called blue-yellow colorblindness, which means someone has trouble telling apart – you guessed it! – blue and yellow.

Because they have a problem with their blue cones. Other types of animals can have different numbers or types of cones. Dogs, for example, only have two kinds of cones in the first place, so they see the world a little bit like some people with red-green colorblindness do.

Red and green probably look more like shades of blue and yellow and gray to them. So if you’re buying a dog toy … your dog will probably have the most fun with a bright yellow or blue ball. A red ball won’t look so great to a dog.

But what if you had more than three types of cones? A few lucky people see the world through four! We can’t imagine what the world looks like to them, but I’ll bet it’s pretty exciting.

And for some animals, it gets even more exciting that! For example, a flower that looks just looks plain yellow to you might look totally different to a bee! Bees have three kinds of cones to see color, just like us.

But instead of seeing red, green, and blue, their cones look for green, blue … and something called ultraviolet light. That’s a type of light that’s invisible to us, but it is there. And bees can see it!

It’s kind of like a trade … we can’t see ultraviolet, but we can see red, and bees can’t see red, but they can see ultraviolet. And to get bees to land on them, some flowers have not only the pretty colors that we see, but other patterns, too, painted in the ultraviolet light that bees can see, and we can’t. To a bee, some flowers that look plain yellow to us actually look like a big target sign!

Some animals can see even more. A type of animal that lives in the ocean called a mantis shrimp can have not three … not four … but twelve or even sixteen different kinds of cones! A few of those cones are just for seeing ultraviolet light.

We’re still learning what the world looks like to them, but if it looks this colorful to us, with our three kinds of cones, just imagine what the mantis shrimp sees when they look at it! 

I also love it when our friends stop by to teach us things.  You can learn a lot from your friends because they see the world in a totally different way.  Bill and Webb taught us about how things float.  Sam the bat taught us about constellations, and do you remember how excited Dino was to tell us that birds and dinosaurs were related?

Greetings, birdbrains! It’s me, Dino!

Jessi asked me to visit the Fort today to talk about my favorite subject in the whole wide world: dinosaurs! You’ve probably heard before that dinosaurs – the giant reptiles that walked the Earth millions of years ago – are extinct. That means they’re not around anymore.

And it’s true that most of the dinosaurs did go extinct. But not all of them. 65 million years ago, big changes were happening in the world. Lots of volcanoes were erupting, and then a giant asteroid collided with Earth, in a huge explosion!

For a long time after that, the world was very dark, then very cold, and then very hot. With no sunlight, a lot of the plants died, so the dinosaurs that ate plants didn’t have enough to eat, so many of them died, too. That meant the dinosaurs that ate other dinosaurs didn’t have enough food either, and a lot of them went extinct.

So, it was a really hard time to be a dinosaur! But some dinosaurs were clever and talented enough to tough it out. Because, their bodies had just the right adaptations — certain traits that helped them survive these big changes.

The dinosaurs that survived had dinosaur babies, and soon their babies had their own little babies, all the way down the family tree. And the animals that came from them are still living here on Earth! We call them … birds!

That means birds like me, Dino, are descendants of dinosaurs, and dinosaurs are my ancestors — like my great-great-great-greatgreatgreatgreat-grandparents! I’m part of the dinosaur family tree! And since birds are part of the dinosaur family, I’m not just a descendant of a dinosaur … I am one!

So the dinosaurs… live! Now, how do we know that birds are related to dinosaurs? Well!

We have lots of clues – specifically, from theropods, a group of two-legged dinosaurs that also included velociraptors and Tyrannosaurus rex! Hundreds of millions of years ago, way before the earliest birds appeared, dinosaurs were developing lots of birdlike adaptations. Theropod dinosaurs especially, started to have a lot of birdlike traits that would later help birds take to the skies!

Like feathers! Lots of dinosaurs – even dinosaurs that didn’t become birds – had feathers. Some of these feathers were more like little hairs, which probably helped dinosaurs keep warm.

But some types of theropods wound up with bigger, fancier feathers, and even wings. Before there were birds, fancy feathers might have been used to keep these dinosaurs and their eggs safe and warm, or to communicate with other dinosaurs. But even though bigger theropods, like some kinds of tyrannosaurs, had feathers, they couldn’t just flap their arms and fly around.

To really be able to get off the ground, you need wide, powerful wings, and a small body. While lots of types of dinosaurs were becoming gigantic, some theropods – including those that eventually gave rise to birds – were getting smaller. So lots of dinosaurs already looked and moved a lot like birds.

And some of the theropod dinosaurs were becoming more like birds all the time! Getting smaller, growing wings, and developing beaks instead of teeth. Over millions of years, all the pieces of the bird puzzle were coming together, one by one.

By about 150 million years ago, the earliest dino-birds were in the air. Some of them could fly, but looked very different from the birds we know today. And some didn’t fly, but had a lot in common with today’s birds!

Millions of years later, when that asteroid hit Earth, and the volcanoes started to erupt, and everything started changing, some dinosaurs had a hard time surviving. A lot of the big ones, like T-rex, were so big, they had trouble finding enough food to eat. But the most birdlike groups of theropods were very small – only about 1 kilogram, or as heavy as a pineapple.

That meant it was easier for them to survive on less food and to find places to live. And because they were so small, these early birds were also able to use their wings to take flight! Not only did some of these flying dinosaurs survive … they really took off!

We have more than 10,000 types of birds around today! So the next time you see one of us feathered friends flying around, you’ll be able to point to it and say, “Hey, look! A dinosaur!”

We can't forget all of the experiments we've done either.  We've made slime, built terrariums, and learned so much by doing all kinds of other projects, and the coolest, weirdest, grossest experiment I think we've ever done is when we made alien eggs.  Remember, Squeaks?

Hi everyone!

Squeaks and I are going to try an experiment today, and we wanted to show it to you! We already know that you can do some cool experiments with eggs — the other day we put an egg in some soda and then brushed it like you brush your teeth!

Today we’re going to put an egg in some other liquids: vinegar, and then corn syrup. And that’s going to make our egg look pretty weird and awesome. Are you excited, Squeaks?

Me too! There are a few things you’ll need for this experiment: Grab an egg, some vinegar, two cups, and corn syrup. This experiment also takes time — you’ll need three days to finish it.

And before you start, make sure that you’re doing your experiment where it’s okay to make a mess, and where you can safely leave your egg for a few days. The first thing you should do is place the egg in a cup. Next, fill the cup with vinegar until the egg is covered.

Now all you have to do is let the egg sit for two days! You can check on it a few times every day to see what the egg looks like, but don’t touch it. OK!

This egg has been sitting in vinegar for two days. And whoa... look what happened! The shell is gone!

So how did the eggshell just disappear like that? Well, there are some things that are good at eating away other things, those are called acids. Soda pop, juice, and coffee all have acid in them, and vinegar has acid in it, too!

When you put the egg in the vinegar, the acid in the vinegar slowly ate away at the eggshell until eventually the whole shell was gone! When you check in on your experiment, notice there are lots of little bubbles all around the egg! Those bubbles formed as the vinegar was eating away at the shell.

After about two days, you should also be able to pick up your egg. But, be careful, because the egg doesn't have a shell! There is a thin covering, called a membrane, and that’s what keeps the egg together even without the shell.

But you can see right through the membrane to the egg’s insides! Can you see anything else that looks different about this egg? That’s right!

The egg also looks bigger than it did before. That’s because some of the water in the vinegar flowed through the membrane into the egg. See, vinegar is really watery, but eggs aren’t as watery.

So some water moved from the vinegar to the egg to help make them more equal. And that made the egg bigger! Now, what do you think will happen when we put the egg into corn syrup?

Corn syrup is really thick and sugary — so do you think more water will move into the egg, or will water flow out of the egg and into the corn syrup? Let’s find out! Ok!

Fill your other cup with corn syrup and very carefully place the egg inside. Now, just wait for one more day. It’s been a day since we put our egg into corn syrup, and look what happened!

The egg shrank! It looks like some kind of weird alien egg now. The egg got smaller because corn syrup has so much sugar in it that it’s even less watery than the egg.

So water moved from the egg, which was more watery, to the corn syrup, which was less watery, to try and make them more equal. And now we know: when you put an egg in vinegar, the eggshell disappears and the egg gets bigger. When you put the same egg into corn syrup, the egg shrinks!

And that’s how you make an alien egg!

Even though we're going to be gone for a while, you can always come back here and watch your favorite episodes, too.  There's always more to learn.  The world is full of amazing knowledge, so go to the library, ask your parents to help you find more shows like this one, and just keep observing the world around you, and you'll never stop learning.

Okay, Squeaks, I think we're all packed up here.  Are you ready?  Thank you all so much for hanging out with Squeaks and me at the Fort.  We couldn't have done it without you.  See you soon.  

(Endscreen)