Hey it's me Destin welcome back to Smarter Every Day.

I'm in Caleb's room. Caleb is a science fair winner, so he is

legit, and you dropped the cat in the cat drop video right?

- Yes. - And we had a deal right? I paid you with something. What did I pay you with?

- These Lego motors. - That's pretty cool.

But I called you and I said I want you to build something for me for a video. What is it?

- This Lego inchworm. This battery pack allows

the motor to turn, which powers the axle,

the worm wheel, the cam which drives the whole thing, and this

ratchet, it allows the worm to move in one spot

so it doesn't do this. - That's awesome. Oh when you take the ratchet off it doesn't

work so you have to put the ratchet back on? So it pushes against itself.

That's awesome. So I have been fascinated as long as I can

remember with locomotion. That's why Caleb got these motors. So today

on Smarter Every Day we're gonna look at caterpillar locomotion. But we have to go back to the Amazon rainforest

to see it. It's a group of caterpillars doing something really strange.

Let's get Smarter Every Day.

So check this out. Gordon found a big caterpillar that's basically

a macro organism of a bunch of little caterpillars.

And they're all moving as one.

That's weird.

- They all stop and think at the same time too. See that?

(Destin) Gerson, do you know a word for this? - No.

- See they all stop at the same time.

- Oh that's weird.

If you look, like for a

school of fish or birds it's usually the bird or the fish in front that dictates where the whole

group goes. But if you look at the caterpillars when they're stopping they're doing this little

stop and think technique, you'll notice that it propogates from the back to the front sometimes.

That's really strange. I wonder what kind of clock or rhythm is dictating this.

I don't know. Look at it. Really weird.

Alright note to self.

Go back and look at the video of the caterpillars and see if the ones on top

are moving twice as fast as the ones on bottom, or depending on how many layers up they are

if they're moving like three times as fast. So it wasn't until I got here and started playing with Legos that I

realised it's not only the second and third level of caterpillars that's moving faster,

it's the entire group as a whole. OK to demonstrate this we're gonna have a Lego drag race. You can

see I've got a single caterpillar on this side and I have a whole group of caterpillars on this side.

At each frame I'm gonna move the single caterpillar one click and I'm gonna move the ones on

bottom one click as well as the ones rolling across the top one click. Keep your eyes

on the blue caterpillars. Ready, set, wiggle.

[slurping sounds]

So you can see from our little race here that the

caterpillar that was by himself is a lot slower than the caterpillar that was in the group.

Now we had two levels. So does that mean that this moved twice as fast?

No it doesn't. Do the math for me by looking at these grids and let me know in the comments how much

faster. But think about this. What if we had three levels or even more?

How much efficiency do the real caterpillars add every time they add a level?

I think the coolest part is that they all stop at the same time.

Look at that.

Then they start back up. Tactile communication right?

So thank you for learning about caterpillars with us, and thank you

to you Caleb for playing Legos with me, and now I will earn your subscription

by walking across Legos barefoot. - Hope that goes well. - I don't owe you anything do I?

We're good? We're square? - We're good, we're square. - OK. Have a good one.

You're getting Smarter Every Day.

So I vote we call this a brood of caterpillars.

- A brood? - What are you gonna call it Gordon? - A slather.

- Ah ooh. [laughs]

Oww, oww.

- Hurts, doesn't it? - Yeah, sure does. - Then you see more crazy stuff

in like ten minutes out here than you do in a whole year back home.

That's it. That's cool. Let's go another twenty feet and find something else in the rainforest.

[laugh]