Jane: Hey, Jane, here for today's episode. We're doing
something a little different. We're going to be listening to
our online video series, But Why Bites. Every other week over on
our YouTube channel, we answer one kid question in a short and
sweet little video. You can find all of them at the But Why kids
channel on YouTube, and we have a link to this compilation of
episodes in our show notes. We're calling it a Big Bite. But
if you're more of a listening kid, this episode is for you.
We're calling it a Big Bite. Hope you enjoy it!
Louie: Why do people change presidents?
Jane: One of the big differences between the U.S. president and a
king or queen or Supreme Leader is that the President doesn't
stay in power as the leader of the country forever. A president
can only serve two, four year terms. That's it. Well,
technically, the president can only be elected twice, but they
could serve a few more years if they're appointed first, like if
the president they're replacing has decided to step down or has
died while in office. But generally speaking, a president
can only serve two terms. That's actually only been a rule since
1951. Before that, there was no official limit on how many times
someone could be elected president. But after the first
U.S. president, George Washington stepped down after
two terms, it became kind of an unwritten rule. But then one guy
named Franklin Delano Roosevelt was elected four times in the
1930s and 40s, and after that, an amendment was made to the
Constitution making that rule about only getting elected
twice. Now, the reason we have this whole president thing in
the first place is because the U.S. was founded with the idea
of democracy, that people have a right to choose their leader,
not be ruled by someone who they don't choose. And if we elect
someone new every four or eight years, the idea is no one can
become president for life. I don't know about you, but there
are a lot of things I'd like better than a president for
life. How about ice cream for life? Or puppies for life? A
lifetime supply of puppies! Now that's something I'd be happy to
vote for.
These dancers behind me are with the Dance Theatre of Harlem, and
they're preparing for an upcoming show. Look at how
strong and beautiful they are, and sometimes they look like
they're dancing right on the tips of their toes. How do they
do that?
Harper: Why do ballerinas wear ballet shoes?
Jane: Some ballet shoes are just simple slippers that help ensure
a dancer doesn't slide on the stage when they don't want to.
But often, when we think about ballet shoes, we're picturing
pointe shoes that help a dancer dance right up on top of their
toes.Toe or pointe shoes spelled P, O, I N, T, E, started being
used by dancers in the 1800s they're designed to support a
dancer's foot and take some of the weight of the dancer,
allowing them to lift up onto their toes without crushing or
breaking delicate foot bones. But it takes years of practice
and building up of muscles before a ballet dancer can start
dancing on point. Lindsey Donnell is a company dancer with
Dance Theatre of Harlem. She's been dancing since she was three
years old, but wasn't allowed to go on pointe until she was 11.
What did it feel like when your teacher first said, Okay, you
can dance on pointe.
Lindsey Donnell: I was so excited. It was a dream come
true, because that is what I've been working for.
Jane: Why did you have to wait so long?
Lindsey Donnell: I had to train and build technique and muscle
strength to make sure that my toes could support my whole body
weight.
Jane: How long does a pair of pointe shoes last?
Lindsey Donnell: It depends on what we're doing, also sometimes
the time of year, because when in the summer, when it's really
hot and sweaty, they'll break down. I usually go through about
two pairs a week.
Jane: So in the course of a year, that means you could be
going through 100 pairs or more.
Lindsey Donnell: That's right.
Jane: But that being said, even the best shoes aren't making the
dancer brilliant. That's all down to the strength and beauty
of the dancer herself, so she can hop, pirouette and arabesque
on the tips of her toes.
If you're ever in the path of a total solar eclipse, the skies
will darken like nighttime and stars will be visible during the
day. But don't worry, you won't have to get your PJs on. A total
eclipse only lasts for a few minutes. But why does the sun
disappear?
Camila: What is a solar eclipse?
Jane: A solar eclipse happens when the moon moves between the
Sun and the Earth. As the moon moves in its orbit, it will
partially cover the sun for over an hour, until the sun is
totally blocked. That's called totality. The sky will be dark
and the sun's corona, the gassy atmosphere, will be visible.
Totality can last anywhere from one to seven minutes, depending
on where you are in the path. Then the eclipse will be partial
for another hour or more again, as the moon continues in its
orbit away from the sun. It's rare to have a total eclipse in
any one place, so seeing one can be a once in a lifetime
experience, and some people travel all over the world to
catch one. If you're going to watch an eclipse, you need to
protect your eyes. The bright light of the sun can damage them
even while the moon is partially in front of it. So you have to
wear something like these eclipse glasses. Once the sun is
totally covered, it's safe to briefly remove those glasses and
look up. You may see the sun's corona, but once the Eclipse
moves back into partiality, it's important to put your glasses
back on. If you don't have any eclipse glasses, that's okay.
Try to get near a tree and look at the ground. The shadows of
the sun passing through the leaves should make some really
cool shapes.
Coming up more But Why Bites. We'll be learning about
jellyfish, cat whiskers, dolphins and chameleons.
This is But Why: a Podcast for Curious Kids. I'm Jane Lindholm.
We're listening to the Big Bite, a bunch of episodes from our
YouTube series But Why Bites. Let's dive back in.
An estimated 150 million people get stung by jellies each year.
How can an animal that's 95 percent water, with no brain, be
so venomous?
Clinton: Do all jellyfish sting?
Jane: All jellies can sting. They have cells called
pneumatocysts inside their tentacles that release venom
when touched. A single tentacle can contain thousands of
pneumatocysts making for a very potent attack. If a small fish
or other animal swims into the tentacles and gets stung, the
venom paralyzes them, allowing the jelly to bring the fish up
to its mouth and eat it. That venom also acts as the jelly's
main defense mechanism. If you brush up against the tentacles,
those pneumatocysts spring into action to protect the jelly.
Jellies have no brain and no heart, and they're technically
not fish. Although a few species can actively hunt, most jellies
swim along with the current in the ocean, trailing their
tentacles and waiting for something to swim into them.
Some jellies are tiny, with a body the size of your thumbnail,
while others, like the lion's mane jelly, can be eight feet
across and have tentacles that stretch 100 feet. But most
jellies are not dangerous to humans. In fact, you wouldn't
even feel many species stings, but a few species are quite
dangerous. So it's always a good idea to steer clear of jellies
if you're not sure what you're looking at. And whatever you do,
don't pee on a jelly sting. That's a myth, and could
actually do more harm than good.
Cats come in all shapes and sizes. Some are small and live
in our homes, and others are large and live in the jungle.
But there's one thing they all have in common, whiskers and not
just for show, those bristly hairs have an important job.
Bryce: Why do cats have whiskers?
Jane: When I think of a cat's whiskers, I'm usually picturing
the ones right here, but cats have whiskers in other places
too, above the eyes, on the chin, on the fore, legs, near
the ears and above the upper lip, that's a lot of whiskers.
Whiskers are thicker, stiffer and longer than most of a cat's
fur, and they're more deeply embedded around the root of each
whisker are nerve endings that can send a signal from the tip
of the whisker right to a cat's brain. Whiskers help a cat sense
its surroundings. They can sense not only the slightest touch,
like a speck of dust landing near an eyelid, but even
differences in air currents and air pressure so a cat doesn't
have to be touching a piece of furniture or its favorite prey
to know it's there. That's especially helpful at night,
when many wild cats like to hunt for their food, whiskers help
them essentially see in the dark. Most house cats have 12
whiskers on each cheek, for a total of 24. Lions have four or
five rows of whiskers on each side of their face, and the top
row has a different pattern, so researchers can use their
whiskers like fingerprints to tell each lion apart. One more
cool fact about these special hairs, cats whiskers have
special sensory organs called proprioceptors that help a cat
stay balanced. Who knew whiskers were part of the secret to why
cats always land on their feet.
Nancy: Why do dolphins jump in the air?
Jane: There's lots of debate about why dolphins jump out of
the water, but we know at least one of the things they do while
they're up there, they grab a breath of fresh air. Like us,
dolphins are mammals. That means, even though they live in
the sea, they need to breathe air to survive. When they're
under water, they hold their breath and they have some pretty
impressive lungs. One species called rissos, or gray dolphins,
can stay down for as long as 30 minutes. Other species have more
like a 10 or 15 minute limit. Let's see how long we can hold
our breath, ready?
I guess I'm no dolphin. So when they jump, they can take that
big, deep breath, and then they can peek at what's happening up
above the water while they're there. Another reason they jump
could be for speed. There's less resistance when you're flying
through the air. If you see a dolphin shooting up out of the
water really fast and then smacking down hard, it might be
trying to get rid of a whale sucker, a type of fish that
latches onto the dolphin's skin to eat parasites it finds there.
That does sound irritating. And if you're saying to yourself
that if you were a dolphin, you'd leap out of the water just
for the fun of it, you might be onto something. Though, jumping
does take a lot of energy. Scientists think dolphins
sometimes do it just because they like it gives new meaning
to the phrase jumping for joy!
Jonathan: How do chameleons change color?
Jane: You've probably heard that chameleons change color to blend
into their background and hide, but new research shows they're
more often adjusting appearance in order to regulate their body
temperature or to communicate. Chameleons can't just match the
pattern of any environment they find themselves in, and to be
honest, they usually don't have to. They're already pretty well
camouflaged. They can get a little lighter or darker,
though, to better match their surroundings. And since lizards
are ectothermic, meaning they can't regulate their own body
temperature, they sometimes change their hue to help them
absorb more or less sunlight, but their most dramatic color
changes are saved for communication, to attract a mate
or defend their territory. To make bold colors chameleons have
special nanocrystals in their skin that they can move closer
together or farther apart by tensing and relaxing. Changing
the positions of those crystals allows them to reflect different
wavelengths of light, making them appear different colors.
Wish I could do that!
That's our last But Why Bite for today? If you want to see this
episode and all the cool graphics that go with it, check
out our YouTube channel But Why Kids. You'll find a direct link
in the show notes. As always, if you have a question about
anything, have an adult record. You asking it on a smartphone.
You can use an app like voice memos, then have your adult
email the file to questions@butwykids.org But Why
is produced by Melody Bodette, Sarah Baik, and me, Jane
Lindholm at Vermont Public and distributed by PRX. Our video
producer is Joey Palumbo, and our theme music is by Luke
Reynolds. If you like our show, please have your adults help you
give us a thumbs up or a review on whatever podcast platform you
use. We'll be back in two weeks with an all new episode. Until
then, stay curious. You