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Ask Dr. Universe melissamayer
University Communications Network > Ask Dr. Universe > Articles by: melissamayer

What is the likelihood that all your lysosomes could burst at the same time? Would you spontaneously dissolve? – Annika, 12, Pennsylvania

Dear Annika,

I’d love to read a creepy science fiction story where people dissolve.

I asked my friend Anders Omsland if that could happen. He’s a biomedical researcher at Washington State University.

He told me a lysosome is a specialized compartment in a cell. It’s like a little sack of digestive enzymes. Those are proteins that break stuff down. Our cells use lysosomes to help destroy germs or recycle old or messed up cell parts.

Lysosomes are basically the cell’s trash and recycling centers.

“I don’t think it’s possible for lysosomes to all pop at the same time,” Omsland said. “They don’t really explode … » More …

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Why do we lose our hearing when we get older? – David, 10, Wisconsin

Dear David,

I love visiting with my grandcat. But sometimes I have to talk loudly so she can hear me.

I asked my friend Christine Portfors why that is. She’s a biologist at Washington State University.

She told me it’s all about the hair cells inside our ears.

They aren’t really hairs. They’re sensory cells. Hair cells have tiny, bristle-like tufts that stick out—called cilia—that look a little bit like hairs.

Those hair cells are why we can hear.

First, sounds funnel into our ears. They bonk into the ear drum and make it vibrate. Then, three itty, bitty bones make those … » More …

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What is a supernova? – Grady, 7, Oklahoma

Dear Grady,

I was exploding with excitement to ask my friend Guy Worthey about supernovas. He’s an astronomer at Washington State University.

He told me a supernova is a very energetic explosion in space.

There are different kinds of supernovas. One kind—called a type II supernova—happens when a really big star dies.

“Why would a star bother to blow up?” Worthey said. “It seems dramatic. Human beings don’t blow up when they die.”

But humans don’t have cores that do nuclear fusion. Deep inside a star, protons and neutrons bang together and make new chemical elements. That nuclear fusion is why stars shine.

… » More …

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How do bugs cling onto things without falling off? – Carmen, 7, Washington state

Dear Carmen,

Right now, there’s a fly walking on the window in my office. I asked my friend Rich Zack how it does that. He’s an insect scientist at Washington State University.

It turns out my window isn’t as smooth as it looks. If we zoomed in on the glass, we’d see bumps and dips. It’s kind of like a rock face or a climbing wall.

“Surfaces look pretty smooth,” Zack said. “But if you get really, really close, you see there are all kinds of little indentations and crevasses. Even a pane of glass is not perfectly smooth. It’s got little nicks and … » More …

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What’s the reason people are grumpy? – Braelyn, 13, Oklahoma

Dear Braelyn, 

Everyone feels grumpy sometimes—even a cheerful cat like me.  

Sometimes exhaustion makes us crabby. When we really need sleep, our brains struggle to do their jobs—like managing our emotions. Sometimes hunger makes us cranky. Our brains need a steady supply of sugar energy. When the available sugar drops too low, we feel terrible—or even hangry. Sometimes stress or problems like anxiety and depression make us grumpy. 

In all those scenarios, anger lets us know we need to change something. We need to sleep, eat or get some help with our problems.  

I asked my friend Anthony Lopez why we feel anger … » More …

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Why do glow-in-the-dark things light up when it’s dark? – Haygarth, 5, United Kingdom

Dear Haygarth,

I love glow-in-the-dark stickers. I leave them next to a sunny window for a little while. Then turn off the lights and watch them glow.

I asked my friend Hergen Eilers how those stickers work. He’s a physicist at Washington State University.

He told me that glow-in-the-dark things use a type of phosphorescence. That means they absorb energy—like light—and then glow. A material that can do that is called a phosphor.

Glowing in the dark works because of electrons.

Everything in the universe is made of atoms. That includes you, me, whatever you’re reading this note on—and glow-in-the-dark stickers.

All those … » More …

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What's the weirdest thing found on Mars? – Remmi, 8, Texas

Dear Remmi,

Mars is about 140 million miles from our cozy planet. A human mission to that cold, rocky neighbor would mean being away from Earth for about 3 years. But the things those explorers would see and learn would be mind-blowing.

I asked my friend Katie Cooper about that. She’s a scientist at Washington State University. She studies how geology and physics work on Earth and other places in space.

She told me the weirdest thing on Mars is a ginormous volcano.

“Olympus Mons is the largest volcano in the solar system,” Cooper said. “It dwarfs Earth’s volcanoes! Its massive size helps … » More …

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What are protons made of? – Dean, 11, Utah

Dear Dean,

There’s a pencil lying on my desk right now. It’s not much to look at, but what if I could zoom way in and see the protons and other itty-bitty stuff inside it?

My friend Ryan Corbin told me it would be like looking at a bubbling soup of fundamental particles. He’s a quantum physicist at Washington State University.

He told me that protons—along with neutrons—form the nucleus in the middle of an atom.

“Atoms make up all the stuff that we see,” Corbin said. “An atom has neutrons and protons in its nucleus. Protons have a positive electric charge. Neutrons … » More …

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How do sedatives work (like for endoscopy)? – Zara, 11, Colorado

Dear Zara,

I love visiting the vet. But, like many cats, sometimes I need medicine to keep me calm.

I talked about that with my friend Lais Malavasi. She’s a veterinarian at Washington State University.

She told me about two kinds of calming medicine. Vets and human doctors use them to reduce pain and fear.

Sedatives make patients feel relaxed and sleepy. But they’re mostly aware of what’s going on. When the medicine wears off, they’ll probably have fuzzy memories.

Anesthesia makes patients unconscious. They can’t feel pain or move. They aren’t aware of what’s going on. When they wake up, they won’t … » More …

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Why do we have two intestines? – Dru, 11, Illinois

Dear Dru,

When it comes to intestines, it sure seems like two are better than one.

I asked my friend Franck Carbonero why that is. He’s a microbiologist at Washington State University. He studies the bacteria that live inside the human gut.

He told me that the small intestine and the large intestine do different jobs.

Let’s say you sink your teeth into some pizza. You chew it up and swallow it. All those chewed up bits land in your stomach. They mix with digestive juices and start to break down. The broken-down food and digestive juices together are called chyme. After … » More …

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What happens when you get your wisdom teeth removed? – Lucy, 9, Rhode Island

Dear Lucy, 

Cats like me don’t have wisdom teeth. So, imagine my surprise to learn some of my human buddies get extra chompers. 

I asked my friend David Carsten about it. He studied biochemistry at Washington State University. Now he’s a dentist who teaches about dental sedation and anesthesia at Oregon Health & Science University. 

Dr. Carsten told me that humans can get three sets of permanent molars. Molars are the big grinding teeth in the back of your mouth. The third set—also called wisdom teeth—usually come in when you’re between 17 and 21 years old. If you get them at all. 

Wisdom … » More …

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Insects are scary to me. Should I be afraid of bugs? Can you help me not be afraid please? – Devyn, 6, Ohio

Dear Devyn,

I love insects, but—between you and me—I’m a little scared of spiders. I’ve been nervous around them ever since I was a kitten.

I talked about our fears with my friend Paul Strand. He’s a psychologist at Washington State University.

He told me that anxiety about insects or spiders is common. Some people even have phobias of them. That’s an intense fear that causes distress.

Many common fears involve things that were probably dangerous to our ancestors—like snakes, the dark, heights and social rejection.

Strand told me that being afraid of insects is similar.

“It’s almost like a double whammy,” he said. … » More …

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Why do people have allergies? – Hailey, 11, Washington state

Dear Hailey,

Under my lab coat, I have a splendid fur coat. That can be a problem when I work with someone who’s allergic to cats.

I asked my friend Ed Johnson about it. He teaches classes about the human body at Washington State University.

He told me that allergies happen when your immune system overreacts to a normal thing it perceives as a threat to your body. That thing can be pollen, dust, food, medicine, insect venom or something else. It can be bits of fur and shed skin called cat dander.

“The immune system evolved to protect the body,” Johnson said. … » More …

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Why is snot green? – William, 7, United Kingdom

Dear William,

There are lots of unpleasant things about being sick. Leaking slimy green snot is near the top of my yuck list.

I talked about it with my friend Linda Eddy. She’s a nurse for kids. She runs the nursing program on the Vancouver campus of Washington State University.

She told me that snot is normally clear. It turns yellow or green when our bodies fight germs that can make us sick.

Snot is also called mucus. It’s a thin, slippery liquid that covers many of the surfaces inside our bodies. You can find mucus in your nose, mouth and eyes. It … » More …

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Are fishes related to humans? – Sarah, 9, Nigeria

Dear Sarah,

Tuna, salmon, mackerel. Cats like me are famously big fans of fish. But I’ve never looked at my afternoon sushi and wondered if it’s related to my human friends.

So, I asked one of those friends named Thomas Siek. He’s a biological anthropologist at Washington State University. He studies how humans evolved.

He told me that fish and humans are distant relatives. All vertebrates—animals with backbones—are related.

“Humans and fish aren’t close evolutionary cousins,” Siek said. “We’re part of the same phylum called Chordata. We share a common ancestor. Those in Chordata have backbones. So, this will also include birds, dogs, … » More …

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Do plants have feelings or consciousness? – Ella, 10, Wisconsin

Dear Ella,

I love plants. But when I hug a tree, does it love me back? Does it think about anything at all?

I talked about your question with my friend Michael Knoblauch. He’s a plant scientist at Washington State University.

He told me that whether or not plants have feelings or conscious thought is an open question. Right now, most scientists think it’s unlikely.

Animals like us feel and think—and we’re aware that we feel and think. Scientists believe that has to do with how our brains evolved.

Plants don’t have brains and nervous systems like ours. They can send and receive … » More …

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How do glasses work? – Prisha, 8, Pennsylvania

Dear Prisha,

I got glasses as a kitten. I put on my new spectacles and was floored by the crisp details. I had no idea you could see individual leaves on trees. I thought everyone saw a green blur.

I talked about that with my friend Dr. Rachna Narula. She’s an eye doctor—called an optometrist—at Washington State University.

She told me that glasses help direct light to the correct spot in the eye so we can see.

“If someone's eyeball is too short or too long, glasses help focus the image on the retina because that’s where the person can see,” Narula said.

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What is the largest insect in the world? – David, 10, Wisconsin

Dear David,

I like big bugs. I cannot lie.

But which insect is the biggest? I asked my friend Rich Zack. He’s an insect scientist at Washington State University.

He told me the answer depends on how you define big.

One way is how much matter makes up an insect’s body. The insects with the most body mass are giant beetles. These include titan beetles, Goliath beetles, rhinoceros beetles and elephant beetles. They can be the size of a mouse.

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What makes snow sparkle? – Hillary’s 1st graders, Washington State

Dear 1st graders,

I love bright, snowy days. That’s when you’ll find me building snowcats, throwing snowballs and watching the sun sparkle on the freshly fallen snow.

I asked my friend Von Walden why that sparkle happens. He’s an atmospheric scientist at Washington State University. Some of his research takes place near the North Pole and the South Pole.

He told me that snow sparkles because of the way snowflakes interact with the sun.

It turns out snowflakes are ice crystals. On Earth, snowflakes are hexagonal. That means they’re crystals with six sides.

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Why in the world is the ice that polar bears depend on melting? — Maeve, 7, Canada

Dear Maeve,

There’s just something special about those powerful, snow-white polar bears. That’s probably why it’s so hard to learn about what’s happening to their habitat.

I talked about that with my friend Anthony Pagano. He used to work with the grizzlies at Washington State University’s Bear Center. He studies polar bears in Alaska.

He told me that scientists classify polar bears as marine mammals—like whales, dolphins and other mammals that live in the ocean.

“They’re reliant on the sea ice that occurs over the Arctic Ocean,” he said. “They use the ice as a platform to catch seals.”

Polar bears spend … » More …

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What happens to the pill capsules after you swallow the pill? – Avery, 11, Illinois

Dear Avery,

I think it’s really cool when a clear pill has teeny tiny balls of medication inside it. My paws itch to bat it around—but I know medicine isn’t a toy, so I sharpen my claws on my desk and then get back to answering your questions.

I asked my friend Damianne Brand-Eubanks what happens after you swallow one of those capsules. She teaches in the College of Pharmacy and Pharmaceutical Sciences at Washington State University. She’s an expert on medication.

She told me that the outside of a pill capsule is usually made of gelatin. That’s the same stuff that’s in jello or gummy candy.

“Just like with food, you swallow the pill, and it goes down the esophagus into the stomach, where there's a whole bunch of acid,” Brand-Eubanks said. “That acid breaks down the gelatin capsule.”

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Why do bees make honey? – Gabby, 9, Kansas

Dear Gabby,

As a science cat, I don’t stir honey into my tea or drizzle it on my biscuits. I don’t have taste receptors for sweet things. Honey doesn’t have a taste to me.

But my human friends gobble up the honey made by the Washington State University bees. I asked my friend Rae Olsson why bees make that sticky stuff in the first place. Olsson is an insect scientist.

It turns out honey is the way honey bees store food for the winter.

“Just like we store food in our refrigerators and pantries, bees turn nectar from flowers into honey, so it doesn’t spoil,” Olsson said.

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Why are heart attacks so dangerous? – Jack, 8, England

Dear Jack,

When I go to the veterinarian for a checkup, one of the first things they do is listen to my heart. They want to make sure it’s healthy because it pumps blood to my whole body.

I asked my friend Zhaokang Cheng about heart attacks. He’s a scientist at Washington State University. He works on new medicines to help people who have heart attacks or heart disease.

He told me that a heart attack happens when a big blood vessel that delivers blood to the heart gets blocked. Those blood vessels are called coronary arteries.

They get blocked when fatty gunk and other stuff build up on the walls of the arteries. Over time, the buildup can get thicker and harder. It can make the space inside the artery very narrow, so there isn’t much room for blood to get through. Or it can block the artery completely.

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What caused the first mass extinction on Earth? – Aayush, 10, New Jersey

Dear Aayush,

It’s sad when living things go extinct. That means they’re gone forever. I think about extinct unicorns all. the. time.

My friend Jodi Rosso told me that a mass extinction is when a huge number of species die out all at once. She teaches earth science at Washington State University.

“There are periods when a whole lot of animals and plants die off in a short time,” Rosso said. “When we say a short time, we mean less than 2 million years. From a human perspective, that's forever. But in geologic time, that's short.”

Groups of living things are always expanding or shrinking their numbers. Scientists think there are as many as 10 million species on Earth right now. Between 100 and 10,000 of them go extinct every year.

A mass extinction is when big percentage of all species die off.

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What happens if we drink too much water? – Joseph, 7, United Kingdom

Dear Joseph,

As an early-rising science cat, I always lap up a bowl of coffee in the morning. After that, I drink fresh water from a cat fountain I keep near my desk.

But what if I drink too much of that thirst-quenching liquid?

I asked my friend Karen Anders if that can happen. She teaches nursing at Washington State University.

She told me that drinking too much water can cause a rare condition called water intoxication.

It’s rare because it doesn’t happen very often. Even if you guzzle lots of water, your kidneys can probably process it. You might feel sloshy and waterlogged. You might throw up, but then you’d just pee the excess water out of your body.

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Why do we get fidgety when we're bored? I have ADHD, and a lot of other people in my school do, too, so I’ve always wondered this. – Amelia, 11, Utah

Dear Amelia,

Sometimes when I’m in a boring meeting, my tail starts twitching. Or I gently rock my office chair.

I asked my friend Amanda Stueber why that helps me. She’s a psychologist at Washington State University. One thing she studies is attention-deficit hyperactivity disorder (ADHD).

She told me that boredom happens when you have less stimulation. That means you don’t have much information coming in from your senses. Like what you see, hear, smell, taste and feel.

When there's no new or interesting info coming in, you start to feel bored and tired. The less stimulation you have, the sleepier you get.

But you can’t just fall asleep wherever you are! So you might play with your hands, bounce your legs or shift your whole body. You may doodle, click your pen or twirl your hair.

That’s your body’s way to keep you awake.

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What causes the northern lights? Are there southern lights, too? – Sebastian, 10, Minnesota

Dear Sebastian,

For many people, seeing the northern lights is the ultimate bucket list item. Lately, experiencing them has gotten a whole lot easier.

I asked my friend Michael Allen about those dancing green and pink lights. He’s an astronomer at Washington State University.

He told me that, along with its light, the sun emits charged particles—mostly protons and electrons. Those particles freely stream into space. Then, some of them bump into Earth’s magnetic field.

Earth has a magnetic field because there’s molten iron in its core. As the liquid metal moves and flows, it makes a giant magnet. The magnet is strongest near Earth’s poles. It makes loops of magnetic energy around the planet that reach out into space.

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What is cancer? – Austin, 9, New York

Dear Austin,

I love a predictable schedule. Knowing when to eat, sleep and answer your questions keeps me chill.

That how the cells that make up our bodies work, too. They grow and die on a predictable schedule. Our bodies constantly make new cells to replace the ones that die. They grow for a set time and then die, too.

But sometimes cells grow out of control. They may grow faster or for a longer time than normal cells. They ignore the signals that tell a cell it’s time to die. They can even spread to other parts of the body and start growing there. That’s cancer.

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How many atoms are in a leaf? – Lily, 8, Georgia

Dear Lily,

I love thinking about things I can’t see with just my eyes. Like the atoms that make up everything.

I asked my friend Fred Gittes how to figure out the number of atoms in a leaf. He’s a physicist at Washington State University.

He showed me a worksheet he gives his students. It included a question exactly like yours!

“It’s a question I assign college students for fun,” Gittes said.

So, you’re in great company when you ponder big questions like this.

We decided to use stoichiometry to find the answer. That’s a kind of math that scientists do to understand chemical reactions.

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Why can’t we tickle ourselves? – Malcolm, 3, Washington

Dear Malcolm,

I was surprised the first time I saw a human transform into a tickle monster. They curled up their fingers and rhythmically poked someone else’s armpits. That is something a cat would never do.

I asked my friend John Wright about it. He’s a retired psychology professor at Washington State University.

I learned that there are two kinds of tickling.

The first is the light tickle you feel when someone gently brushes your skin. Like when someone uses a feather to barely touch the inside of your arm. Scientists call that knismesis.

It turns out you can totally tickle yourself that way. But the feeling will be much more tickly if someone else does it.

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What makes pee so bad that I have to get rid of it? – Jeff, 14, Michigan

Dear Jeff,

The worst thing about being an anthropomorphic cat is that I have to scoop my own litter box. It’s a real drag.

I asked my friend Henry Mroch why we need to pee in the first place. He’s a doctor at Washington State University. He teaches medical students about the organs that make urine—called kidneys.

He told me that most people have two kidneys. Each one is about the size of your fist. They sit near your back, right under your ribcage.

Each kidney attaches to a tube called a ureter. Those tubes take urine to a storage pouch—called the bladder. When you pee, another tube called the urethra moves the urine from the bladder out of your body.

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Why do trees have bark? – Grant, 5, Texas; William, 7, Virginia; Kate, 9, Florida

Dear Grant, William and Kate,

When I was a kitten, I liked to scratch tree trunks. I loved sinking my claws into their bark. Now I mostly hug trees—but I still love the way bark feels under my paws.

I asked my friend Henry Adams why trees have that tough outer layer. He’s a tree scientist at Washington State University.

He told me that bark protects trees.

“Bark is like our skin,” Adams said. “It protects trees from all kinds of attackers that might want to get in—like viruses, bacteria, fungi, insects or even non-living things like fire.”

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Does the sun orbit anything? – Kingston, 11, Illinois

Dear Kingston,

When we think about orbits, we usually picture the Earth zooming around the sun. But does the sun just sit there? Or is it on its own journey?

I asked my friend Guy Worthey. He’s a space scientist at Washington State University.

He told me that an orbit happens because the gravity from something big pulls on a moving object. The sun has lots of gravity because it’s ginormous compared to Earth. So, that gravity pulls on the Earth and holds us in orbit.

But our sun isn’t the only star. It’s one of many, many stars in the Milky … » More …

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How do we get muscles? – Jalane, 10, Ohio

Dear Jalane,

I’ve always been a bookish cat. I spend most of my time in the lab rather than running, prowling and pouncing like most felines.

But I still have super strong muscles. They’re way bigger than when I was a kitten.

I asked my friend Edward Johnson how I got so buff. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

He told me that muscles are made of muscle cells. They’re also called muscle fibers or myocytes.

We usually think cells are way too small to see with our eyes. But muscle cells can be some of the longest cells in your body. They’re shaped like long tubes or hot dogs. Each muscle cell is as long as the muscle it’s part of. So a muscle cell in a grownup’s thigh muscle could be 14 inches long!

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How does sunscreen work? – Seth, 6, Virginia

Dear Seth,

Since I’m a fluffy cat, my fur protects me from the sun. But my hairless cat and human friends use sunscreen when they go outside.

I asked my friend Michael Smerdon how it works. He’s a biochemist at Washington State University.

He told me that the sun puts out different kinds of light. Some light is visible to humans. Some is invisible—like UV light.

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Do butterflies have meat in their bodies? – Fiona, 4, Iowa

Dear Fiona,

When I was a kitten, I loved chasing butterflies. It’s fun to run after them as they flit and flutter.

But I didn’t eat them.

I asked my friend Rich Zack if that was an oversight. He’s an insect scientist at Washington State University.

He told me that insects are animals with muscles just like other animals that people eat—like cows and chickens.

“Insect muscle tissue is almost exactly the same as mammalian muscle tissue,” Zack said. “So, if there were a way to get that muscle tissue and process it, you could eat an insect steak or an insect hamburger.”

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Why do birds migrate? – Lebron, 9, Virginia

Dear Lebron,

One of my favorite sights is when geese fly south in a “V” formation. As a cat, I’m pretty independent. So, I think it’s amazing to see birds fly together like that.

I talked about why birds migrate with my friend Heather Watts. She’s a biologist at Washington State University. She studies important animal behaviors like migration.

She told me that migration is a movement animals make that’s outside their normal day-to-day pattern. It’s usually a temporary movement. They leave for a little while and then come back.

Lots of animals migrate, but we usually think of birds doing it. The big reason birds migrate is to find things they need like food and places to nest.

“We think that, in most cases, birds are migrating to make use of resources—and that's usually food that's available only at some times of year,” Watts said.

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Why is the sun so hot? – Ziyonna, 11, Indiana

Dear Ziyonna,

What happens if you do a big jump? Your body goes up into the air. But then it comes back down again. The reason you don’t just keep going up, up, up is because the force of gravity pushes your body and the Earth together.

It turns out gravity is a big reason the sun is so hot. That’s what my friend Michael Allen told me. He’s an astronomer at Washington State University.

He said that, at first, the universe was like a thick soup of gas and dust. Then, gravity pushed some of the gas and dust together. That’s how stars … » More …

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What is the human brain made out of? – Trevor, 9, Illinois

Dear Trevor,

Everything we do and think is thanks to the 3-pound organ tucked into our skulls. But what is it made of?

I asked my friend Samantha Gizerian. She’s a brain scientist at Washington State University.

She told me the brain is surprisingly soft and mushy.

“We think about our other organs and tissues, and they’re squishy in a very solid way,” Gizerian said. “Like when you go to the grocery store and get a carton of meat. You can squish on the steak, right? Our other organs are mostly like that as well. But the brain is very, very delicate.”

She told me it’s more like the ground up burger people use to make meatballs. Or like soft tofu or a Jello square.

The brain is extra soft because it’s about 60% fat.

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Did man live with dinosaurs together? – Daniel, 9, Republic of Korea

Dear Daniel,

When I think about dinosaurs, I usually picture the big ones. I think of triceratops with its pointy horns or apatosaurus with its long, long neck.

I asked my friend John Blong if those dinos ever lived with people. He’s an environmental archeologist at Washington State University. He studies early humans.

He told me that people and dinosaurs never lived at the same time. Well, mostly.

Dinosaurs went extinct 66 million years ago when a giant asteroid crashed to Earth. It threw up tons of dust and soot. It made Earth super cold and dark. It stayed that way for a long time. The world became a very hard place to live. Eventually, 75% of all living things died, including all the big dinosaurs.

People didn’t live on Earth at that time. The only mammals that lived back then were tiny. They looked like shrews or moles. It would take millions of years before mammals adapted enough to become primates. Scientists think the first humans showed up about 300,000 years ago. That was long after the dinosaurs died out.

But some dinosaurs survived the asteroid.

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Why do bugs fly in a big group? What are they doing? – Hudson, 7, Washington state

Dear Hudson,

The other day I walked into a cloud of gnats. I love insects, but it was unpleasant to have all those critters fly into my whiskers.

I asked my friend Rich Zack what they were doing. He’s an insect scientist at Washington State University.

He told me that most insects are individualistic. They don’t usually fly together in groups—unless they need to mate or travel. Then, some insects form a group called a swarm.

“The purpose of the adult insect is to mate,” Zack said. “They have short lives—so short that a lot of them don’t even feed as adults. So, the mating period is very important to them.”

That’s what my gnats were doing.

The conditions outside were just right, so a bunch of male gnats showed up in the same place. When female gnats got there, it was easy for them to find a mate—because everybody was together.

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Can dogs understand what a human says? – Jonathan, 10, Illinois

Dear Jonathan,

There’s no doubt that the relationship between humans and dogs is special. But does your best pupper understand everything you tell them?

I asked my friend Cassidy Cordon. She’s a veterinarian at Washington State University.

She told me that dogs understand lots of human words. But dogs also pay attention to their human’s tone of voice and body language to figure out what the human means.

Let say you teach your dog that “walk” means you’re going to take a stroll. Your dog friend might recognize the word “walk.” But they might also notice that you’re picking up their leash or putting on your shoes. They might pay attention to how excited your voice sounds—and whether that matches your tone when you taught them the word “walk.”

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How can fish see in the water? – Dottie, 7, South Dakota

Dear Dottie,

When I was a kitten, I learned to swim by diving for coins in the pool. It wasn’t easy seeing the coins underwater. It was blurry down there.

I talked about how fish see with my friend Nora Hickey. She’s a fish veterinarian at Washington State University.

She told me that fish eyes don’t work the same way mammal eyes do—even though we have the same eye parts.

Your cornea is the clear, squishy tissue right at the front of your eye. It’s in front of the colored ring in your eye—called the iris. There’s a dark dot in the center … » More …

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Why do people get voice cracks? – Jade, 12, Montana

Dear Jade,

Have you ever heard cats yowling? It’s expressive, that’s for sure. Sometimes when I yowl or sing, my voice cracks a little bit.

I asked my friend Alisa Toy why that happens. She’s a professional singer who teaches in the School of Music at Washington State University.

She told me it has to do with the muscles that move the larynx. That’s sometimes called the voice box. It’s a hollow tube that’s important for breathing and talking.

When you talk or sing, you push air from your lungs up through your larynx. The air passes through an opening made by your vocal folds. Those are incredibly thin tissues in the middle of your larynx. They vibrate as the air whooshes past them. That vibration makes the sound that becomes your voice.

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Why did people stop exploring the ocean? I heard they only explored 5% of it. – Dakota, 11, New Mexico

Dear Dakota,

When I think about exploring the ocean, I think about the discovery of giant tube worms. They live in super- hot, mineral-rich water deep in the ocean. They don’t do normal things like eat or poop—but they can live for 300 years or longer. Scientists were shocked when they found them—and there’s probably much more to find.

[caption id="attachment_7794" align="alignnone" width="396"] These are tube worms that live by underwater volcanoes near the Galapagos Islands. The feathery red part is like a gill. It's filled with blood. It absorbs chemicals from the water and the volcano vent. Image: NOAA[/caption]

I talked about ocean exploration with my friend Gretchen Rollwagen-Bollens. She’s a biological oceanographer and plankton ecologist at Washington State University.

She told me that you’re right that we’ve only explored about 5% of the ocean. But it isn’t because we stopped trying. The ocean is just massive.

The ocean contains more than 321 million cubic miles of water. To imagine that, think of something that’s about a mile away from you. You might need to use a map app. Or ask a grownup for a landmark.

Now picture a giant 3D cube that same distance on each side. It’s 1 mile long, 1 mile wide and 1 mile deep. You would need 321 million of those to equal the ocean. Or think of a 1-gallon milk jug. All the water in the ocean would fill about 325 quintillion jugs.

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Recently there was an online news article that mentioned cold magma that was flowing on the land. What is cold magma? – Matt, 7, Illinois

Dear Matt,

When I think about volcanoes, I picture molten magma deep inside the Earth. Or burning hot lava pouring down the side of a mountain. But you’re right that there have been news reports that mention cold lava.

I talked about what that could be with my friend Katie Cooper. She’s a geologist at Washington State University.

She told me the news may be using “cold lava” to describe a lahar. That’s a mix of water and rocky debris that sometimes whooshes down the side of a volcano. It's also called a debris flow or a volcanic mud flow.

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Why do people like cute animals more than ugly ones? – Brayden, 9, Ohio

Dear Brayden,

Not to brag, but when I was a kitten, humans would see me and squee. Maybe it was my big, sparkly eyes or my teeny, fluffy paws.

I asked my friend Giuseppe Giannotti why people found me so adorable. He’s a scientist at Washington State University. He studies the brain.

He told me that humans like cute animals because they remind them of babies.

“We’re drawn to find traits in animals that are similar to what we think is cute in humans,” Giannotti said. “The cutest things in humans are babies—you know, big heads, giant eyes, soft cheeks—and we project this to everything around us.”

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Why do birds sing in the morning? – Alexandria, 9, Wisconsin

Dear Alexandria,

I usually write answers to kids’ science questions early in the morning. I like how it’s so quiet—except for my bird neighbors singing and singing.

I asked my friend Jennifer Phillips what’s going on. She’s a bird scientist at Washington State University.

She told me birds sing in the morning to tell other birds that their territory still belongs to them.

“The morning time is usually a little bit more calm, especially in windy areas,” Phillips said. “So, it's a good time to broadcast your song and for that song to potentially travel a little farther.”

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Why do we need to hydrate? – Victor, 9, Ohio

Dear Victor,

Is there anything better than lapping up cool water on a hot day?

I talked about why we need to hydrate with my friend Ed Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

It turns out that up to 60% of an adult human’s body is water. A kid’s body contains even more water than a grown up. When you were a baby, you were about 78% water.

Humans use that water for all kinds of things. It keeps you cool when you sweat. It removes waste when you pee. It moves important stuff around inside your body. It even cushions your brain and spinal cord.

But staying hydrated is really about your cells.

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How does your voice make sound? – Bianca, 6, California

Dear Bianca,

Think about all the ways you use your voice: talking, singing, whispering, shouting, yodeling. Humans make so many sounds with just their voices.

I talked about how it works with Alisa Toy. She’s a professional singer who teaches in the School of Music at Washington State University.

She told me that the human voice is the smallest instrument in the world. The parts that make the sound—called the vocal folds or vocal cords—are about as long as your thumbnail.

So, where are those tiny vocal folds and how do they do it?

Inside your throat you have two tubes. The esophagus … » More …

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What safety measures can we take during extreme weather conditions? – Zadok, 8, Kenya

Dear Zadok,

When I was a kitten, a tornado tore through the neighborhood I was visiting. It got eerily quiet outside. Then the sky turned green. My littermates and I climbed into an empty bathtub to stay safe. After that, it got super loud.

I talked about extreme weather with Nathan Santo Domingo. He’s a weather scientist at Washington State University.

He told me that how to prepare depends on where you live. Different places have different kinds of extreme weather.

“Keep an eye on the forecast and know what's coming your way,” Santo Domingo said. “Be smart about what happens in your area.”

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What is the most dangerous insect in the world? – Juan Simon, 9, Chile

Dear Juan Simon,

The deadliest animal on Earth isn’t a shark or a bear. It’s an insect. Mosquitoes kill way more people than any other animal.

I talked about it with Jeb Owen. He’s an insect scientist at Washington State University.

He told me mosquitoes are dangerous because of the way they sometimes eat.

“Through blood feeding, mosquitoes can transmit pathogens that make people and animals sick,” Owen said.

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Why do we have nose hairs? – James and Zion, 10, Virginia

Dear James and Zion,

Despite being a curious science cat, I must confess I haven’t spent much time looking up human noses. But I have noticed that human nostrils can be a bit…furry.

I talked about what’s inside your nose with my friend Edward Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

He told me that nose hairs only grow in your nose’s vestibule. That’s the inside of the part of your nostrils that you can flare out. The nose hair’s job is to filter the air you breathe in through your nose.

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Why do we need the sun? – Samai, 9, Ohio

Dear Samai ,

Right now, the sun is shining through my window. It feels warm on my muzzle.

I talked about the sun with Guy Worthey. He’s a professor of astronomy and physics at Washington State University.

He told me that our lives depend on the sun.

“The sun keeps you warm and powers everything,” Worthey said. “Without it, Earth would be a frozen nightmare.”

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Why do we change our minds? – Stella, 10, Tennessee

Dear Stella,

As a science cat, I’ve changed my mind a lot over the years. I used to wear a fancy neck scarf called a cravat all the time. Now I’m comfy in my lab coat.

I talked about that with my friend Makita White. She’s a graduate student in the psychology department at Washington State University.

She told me that we change our minds when we get new information or insight that tells us we need to make a different choice.

It turns out that we have lots of opinions and beliefs. They’re also called attitudes. We have attitudes about what we like to eat or wear. We have attitudes about other people and how the world should be.

White told me that having attitudes helps us out.

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Why are some veggies called fruits because of their seeds? – Valerie, 10, New Mexico

Dear Valerie,

Every summer I grow peppers in my garden. I always thought they were vegetables. But you’re right that my peppers have gobs of seeds like fruits do.

To figure out what’s going on, I talked with my friend Jacob Blauer. He’s a plant scientist at Washington State University.

He told me that whether something is a vegetable or fruit depends on what part of the plant it comes from.

“Plant products that come from plant parts like roots, leaves or stems are veggies,” Blauer said. “If they come from a flower and bear seeds, they’re a fruit in botanical and scientific terms.”

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Do babies open their eyes when they are in their mom's tummy? – Neela, 6, Washington state

Dear Neela,

My litter mates and I were born with our eyes closed. It takes a week or more for newborn kittens to open their eyes and see the world. But newborn humans can open their eyes and look around right away.

I talked about your question with my friend Cindy Brigham-Althoff. She’s a nurse midwife and professor at Washington State University.

She told me that whether unborn babies can open their eyes depends on their fetal age, or how close they are to being born.

Most babies are ready to be born after about 38 weeks of growing and developing. (Or 40 … » More …

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Why are cats scared of cucumbers/snakes? — Aurelia, 8, Canada

Dear Aurelia,

It’s been almost ten years since someone went viral for recording a cat freaking out about a cucumber. In that video, a human sneaked up behind a cat while it was eating. They silently placed a cucumber behind the cat. When the cat turned around, it jumped super high and ran away. Soon, lots of people were making those videos.

I asked my friend Jessica Bunch why all those cats were scared. She’s a veterinarian at Washington State University.

She told me that cats can be surprised by new things. That’s especially true if the new thing shows up without warning. Or while the cat has its guard down. Like when a cat is eating, and a human sneaks up with a cucumber.

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How are plants considered living if they don't have a heart or brain? – Lily, Pennsylvania

Dear Lily,

You and I are both animals with backbones, so we have lots in common. Our ways of being alive look similar. We have hearts to pump blood. We have brains that help us think and communicate.

But plants don’t have the same body systems we do.

I talked about your question with my friend Michael Knoblauch. He’s a plant scientist at Washington State University.

He told me plants are seriously good at being alive. In fact, 80% of all the living things on Earth are plants.

“Go out in the forest and look around,” Knoblauch said. “You might see birds and … » More …

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What would happen to female honey bees if male bees didn't exist? – Emmie, 12, Arizona

Dear Emmie,

When I want something sweet, I pull out a jar of honey made by my bee friends at Washington State University. I talked about your question with one of the insect scientists there, Rae Olsson.

They told me a honey bee colony includes one female queen, many female workers and, depending on the time of year, some male drones.

Workers have lots of jobs. They gather nectar and pollen. They take care of each other, the queen and the baby bees.

A drone’s only job is to mate with a queen from another colony.

The queen’s only job is to … » More …

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Why do plants need water? – Emma, 9, New York

Dear Emma,

When I’m thirsty, I pick up a glass of water with my paws and drink it—just like you do. But plants don’t have paws or mouths, so how (and why) do they drink it?

To find the answer, I talked with my friend Helmut Kirchhoff. He’s a scientist at Washington State University. He studies plants and biochemistry.

He told me plants need water inside their cells. Water makes plant cells strong and flexible. It also dissolves stuff. That makes it possible for chemical reactions to happen inside plant cells—like the reactions a plant uses to make energy during photosynthesis. Plants also need water to move around nutrients and other molecules required for life.

“Water is essential for life, but plants must move nutrients from the soil to the leaves,” Kirchhoff said. “So, they have this very nice transport system called xylem. Xylem is an ancient Greek word that means wood. It works like a straw to move water and nutrients from the roots to the leaves.”

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Where do frogs go in the winter? – Landon, 13, Washington

Dear Landon,

When the cold weather comes, I bundle up in a sweater and explore the snow.

But my frog friends are never around then. In fact, I’ve never seen a frog in a sweater.

I asked my friend Erica Crespi why that is. She’s a biologist at Washington State University. She studies frogs and other amphibians.

She told me frogs are different from you and me. We’re warm-blooded. Our bodies use energy to make heat. When it’s cold outside, it’s still warm inside our bodies. We just put on warm clothes to keep our heat from escaping.

But frogs are cold-blooded. They don’t spend a lot of energy making heat. So, when it’s cold outside, it’s cold inside a frog’s body, too. That could be bad news during a winter freeze.

Crespi told me that’s why most frogs living in places with cold winters find a slightly warmer place to hunker down.

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How are the insides of an insect different from a human? – Landon, 11, California

Dear Landon,

I love taking selfies with my insect friends. They’re so tiny and look so different from a big cat like me.

But my friend Rich Zack told me that insects and humans have lots in common. He’s an insect scientist at Washington State University.

“There are body systems that every animal needs,” Zack said. “Insects are relatively advanced animals, so they do a lot of things like humans do.”

That means many of an insect’s body systems are like yours. But there are three body systems that are super different for insects. Those are the skeletal, circulatory and respiratory systems.

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Why are dolphins mammals and not fish? – Evie, 9, Washington

Dear Evie,

As fellow mammals, you and I have a lot in common. It’s easy to see our similarities because humans and cats spend lots of time together. We may even be roommates or family.

But humans and cats don’t usually have dolphin besties. It’s harder to see what we have in common when our bodies and lives are so different.

To better understand mammal life, I talked with my friend Kevin Turner. He teaches marine biology at Washington State University.

“The name mammal comes from the presence of mammary glands,” Turner said. “So, the major characteristic of mammals is that we have mammary glands to produce milk for our offspring.”

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Why does milk cure the spicy feeling in your mouth after you eat something spicy but water doesn't? – Eloise, 10, Minnesota

Dear Eloise,

My work as a science cat has introduced me to human foods—like chips and salsa. I love the spicy taste of salsa, but I always keep a saucer of milk handy.

I talked about why milk calms the spicy feeling with my friend Emily Cukier. She’s a chemistry librarian at Washington State University.

She told me that the spicy feeling comes from something called capsaicin. The amount of capsaicin in a pepper determines how hot it is.

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How do people get ear infections? – Lydia, 9, Illinois

Dear Lydia,

Ear infections aren’t fun. They can make your ears hot, itchy or painful. They can cause lots of pressure or make it harder to hear. Sometimes fluid leaks out of your ear.

I asked my friend Bevan Briggs why that happens. He’s a nurse practitioner and professor at Washington State University.

He told me people usually get outer ear or middle ear infections.

Your outer ear includes the flappy part attached to your head—called the auricle or pinna. It also includes the ear canal. That’s the tunnel that goes into your head. At the end of the ear canal, there’s a thin, flexible barrier of tissue called the eardrum. That’s the boundary between your outer ear and your middle ear.

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Why do we have to go to sleep at night, but the other side of the world is having morning? – Braelyn, 12, Ohio

Dear Braelyn,

If I drew a straight line through the Earth to the opposite side of the planet from me, I’d hit a place called Port-aux-Français. That’s an island near Antarctica. Mostly scientists live there.

Right now, it’s 12 PM, or noon, on Friday for me. But those scientists are probably snoozing in their beds. For them, it’s after 12 AM, or midnight, on Saturday. They’re already living in my tomorrow. Weird!

I talked about why that is with my friend David Luftig. He’s a science librarian at Washington State University. Science librarians are experts in two things: science and helping people find information for research and learning.

He told me it’s all because of Earth’s rotation. As the Earth rotates, or spins, the sun shines on one part of the Earth at a time.

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How do flowers use sunlight and water to grow? – Jackie, 8, Virginia

Dear Jackie,

When I was a kitten, my family measured how tall I was. They marked it on the wall. It was amazing to see how much I grew.

I talked about how plants grow with Helmut Kirchhoff. He’s a scientist at Washington State University. He studies plants and biochemistry.

He told me plants grow by making new cells. To make a new cell, an existing cell splits into two. That’s called cell division. Then, the new cells grow bigger. That’s called cell growth. So, a plant can make its stem or roots longer by making new cells in those places. When it’s time to bloom, a plant can make new types of cells that form flowers.

Plants need the right ingredients to do cell division and cell growth.

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Why do marine mammals have horizontal tails, but fish have vertical tails? – Peyton, 11, Washington

Dear Peyton,

When you think about a whale, you probably picture an enormous sea creature without legs. But what if I told you the first whale had four legs and could walk on land?

I talked about whales and other marine mammals with my friend Kevin Turner. He teaches marine biology at Washington State University.

He told me marine mammals have horizontal tails because they flex their bodies up and down to move. Fish flex their bodies side to side. Scientists think it has to do with the way different animals evolved.

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How do animals breathe underwater? – Kinsley, 9, North Carolina

Dear Kinsley,

Have you ever seen a diving beetle? They’re one of my favorite animals. They live underwater and breathe air from a bubble attached to their butts.

I talked about all the ways animals breathe underwater with my friend Wes Dowd. He’s a marine biologist and animal physiologist. He studies how living things interact with the world around them.

Animals need oxygen. For air-breathers like us, oxygen is mixed into the air. For water-breathers, oxygen is mixed into the water. To get oxygen into our bodies, we all need organs and tissues made of very thin material with lots of surface area. That means lots of places that touch the air or water where oxygen can pass through. Like inside lungs or gills. Or the skin of frogs, toads, newts and salamanders that can live on land or underwater.

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How can we help bees survive harsh winters? – Carla, 10, Texas

Dear Carla,

I keep mason bees. They sleep in cardboard tubes all winter long. I worry about my little bees until I see them chew out of their nesting tubes in the spring.

I talked about how mason bees and all kinds of bees survive winter with my friend Brandon Hopkins. He’s an insect scientist at Washington State University. He manages the honey bees on campus.

The honey bees we see in North America today first arrived with Europeans in the 1600s. We love honey bees because they pollinate our crops and make delicious honey. But there are lots of bees that have always lived here—like bumble bees, squash bees and mason bees. Those are native bees.

Most native bees survive the cold by overwintering in the nests where they were born. That could be tucked into the soil or leafy debris. It could be nestled inside hollow plant stems, holes in wood or tubes like my mason bees. Some native bees like bumble bees live in colonies. Only the queen survives the winter. She digs into the earth or finds a hollow tree and hibernates there.

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Why do birds circle when they find food instead of just going and eating it? – Eden, 7, Michigan

Dear Eden,

I live close to a natural area with lots of birds of prey like hawks and eagles. I love to watch them sit in ginormous nests on top of electrical poles. Or swooping around in big circles while they search for a meal.

I talked about why they circle with my friend Jennifer Phillips. She’s a wildlife ecologist at Washington State University. She studies the relationship between birds and the environment.

She told me that birds of prey fly in a circle because they’re riding warm air currents called thermal updrafts or thermals. As the sun heats the Earth, some pockets of air get hotter than others. That warmer air rises. Birds can hop on those warm, rising thermals and ride them. That saves energy.

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Why do some people just seem so much smarter than others, no matter how hard I try to be good at studies? – Alexa, 12, Hong Kong

Dear Alexa,

As a science cat, I talk to some of the smartest scientists on the planet. It can be intimidating. Especially when I talk with people who are experts at things that are hard for me.

I talked about what it means to be a good student with Kira Carbonneau. She’s an educational psychologist at Washington State University.

She told me that everyone grows and learns at different rates. Just like people learn to walk or talk or ride a bike at different rates.

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What is pi? – Johsan, 10, Alabama

Dear Johsan,

One of my favorite holidays is Pi Day. On March 14, people who love the math constant called pi celebrate by eating the other kind of pie. Like apple pie, pumpkin pie and even pizza pie.

I talked about the number pi with my friend Kristin Lesseig. She studies how kids learn math.

She told me pi is the ratio between the distance around a circle and the distance across a circle. A ratio is the relationship between two numbers. We usually think of pi as about 3.14—but there’s more to it than that.

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What and where is the rarest plant in the world? – Thomas, 7, Virginia

Dear Thomas,

Every few years, a smell like a rotting corpse wafts around a stairwell at Washington State University Vancouver. But it’s not really a dead body. It’s the bloom of the corpse flower plant.

There are fewer than 1,000 corpse flower plants left in the wild. It’s one of the rarest plants in the world.

But the list of rare plants is massive. If you look at all the plants we know about in the world, there are about 435,000 different kinds of plants—and many more we don’t know about. Some scientists say that more one-third of all plants are “exceedingly rare.”

I asked my friend Dawn Freeman what makes a plant rare. She’s responsible for the WSU corpse flower.

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How does your body heal cuts and scrapes? – Liam, 11, California

Dear Liam,

Did you know your skin is the largest organ in your body? The average 5th grader has more than 6 pounds of skin. Whoa.

Skin protects the inside of your body from the dirty outside world. It keeps your insides from drying out and ensures a steady body temperature. It lets you feel things you touch.

Your skin also has the incredible ability to heal itself. I talked about that with my friend Edward Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

“Skin is the point of contact between you and everything in your environment,” Johnson said. “So, it's evolved the ability to regenerate.”

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Why do cats rub their cheeks on stuff? – Lara, 10, New York

Dear Lara,

Sometimes I get an overwhelming urge to rub my face on things I love—like my microscope. Other times I’m so happy to see my tortoiseshell roommate that we bump our heads together.

I talked about why I do that with my friend Dr. Jessica Bell. She’s a veterinarian at Washington State University.

She told me that cats rub their cheeks on things when they’re happy or want to say that thing belongs to them.

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Are mermaids real? Is there a species that contains DNA that’s half human and half fish? – Maite, 12, Texas

Dear Maite,

People have thought about mermaids for a long time. Ancient people even drew humans with fish tails on cave walls. So, did they really see mermaids or were they drawing from imagination?

The marine experts from the National Oceanic and Atmospheric Administration (NOAA) say that no mermaids have ever been found in the ocean.

But we’ve fully mapped only about one-quarter of the ocean floor. There are probably between 700,000 and one million different kinds of plants and animals in the ocean. At least two-thirds of those are still unknown to us.

Does that mean mermaids could be swimming around in parts of the ocean we haven’t explored? Maybe. But our best guess is that people mistook other sea animals for mermaids—like manatees and their relatives.

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How do plants that need very little water survive? – Alivia, 11, Maryland

Dear Alivia,

My neighbor has a very prickly garden. It’s full of cactuses—including one thorny plant nearly as tall as my house. That’s not something you see every day in the Pacific Northwest. Cactuses usually live in dry places like deserts.

I talked about your question with my friend Linda Chalker-Scott. She’s a garden scientist at Washington State University.

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What is mutualism in nature? – Luke and Wade, 10, Maryland

Dear Luke and Wade,

When I get the same question from different kids, I know it’s a good one.

So, I talked about your question with my friend Angeliqua Montoya. She’s a graduate student at Washington State University. She works on a mutualism between pea plants and bacteria.

“I study ecology, which is looking at interactions between different species,” she said. “Mutualisms are interactions where both species benefit.”

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How did one comet kill all the dinosaurs? If crocodiles, snakes and birds came from dinosaurs, did it actually kill all of them? — Mya, 11.4, Virginia

Dear Mya,

It’s hard to imagine that one space rock wiped out the dinosaurs. But it did more than that. It killed 75% of the plants and animals on Earth. Me-OW.

I talked about that with my friend Barry Walker. He teaches geology classes about Earth’s history at Washington State University.

Walker told me that we call a space rock that hits Earth a meteorite. The meteorite that took out the dinosaurs set off changes on Earth. Those changes lasted for thousands of years. That’s how it killed so many things.

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How do fish hear? — Lamarcus, 8, Ohio

Dear Lamarcus,

My goldfish roommate hates when people tap on his tank. The tapping sound he hears in the water is loud and scary.

I talked with my friend Rikeem Sholes about how fish hear. He’s a fish scientist. He studies salmon hearing at Washington State University.

He told me that a fish’s hearing system includes sensory cells in the inner ear and in a line along the outside of the fish’s body and head. Some fish also use their swim bladder to have super hearing.

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Besides telescopes and spaceships, how do we really know that there are other planets? – Ia, 12, Montana

Dear Ia,

I looked through a high-power telescope for the first time in college. I couldn’t believe how many stars I saw. It’s hard to imagine all the planets orbiting all those stars.

I talked about how we know those planets are out there with my friend Jose Vazquez. He’s an astronomer at Washington State University.

He told me that scientists look for planets outside our solar system using a number of instruments—like a photometer. That's a tool that attaches to a telescope and measures light.

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Why do cats purr? – Kaylee, 11, Kentucky

Dear Kaylee,

I purr all. the. time. I purr when I get a good question like yours. I purr when I finish answering a question. I even purr when I’m struggling to find an answer.

Luckily, Dr. Sarah Guess says that’s normal. She’s a veterinarian at Washington State University. She told me that cats purr when they’re content and when they’re stressed out. It can be a little confusing for humans.

Scientists have two ideas about why cats purr. It could have come from the way mother cats care for kittens. Or it could keep their bones and tissues healthy.

But experts don’t agree on the answer yet.

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What do robots eat? Why do they have mouths if they don’t eat food? – Oliver, 4, Virginia

Dear Oliver,

I just scarfed down tuna with a side of kibble. That’s how I get the energy I need to investigate your questions.

To do that, I talked with Ming Luo. He’s a robotics scientist at Washington State University.

He told me that robots don’t eat like we do.

“A human has a digestive system,” Luo said. “That’s how food can be converted to energy. But a robot can’t do that. The robot can just take in energy directly.”

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Why do dolphins and beluga whales have echolocation and what is it? – Carolyn Grace, 8, Virginia

Dear Carolyn Grace,

Toothed whales—like dolphins and belugas—might live in the ocean, but they have some big things in common with cave-dwelling bats. They’re all mammals that live in dark places and use echolocation.

That’s why I talked about your question with my friend Christine Portfors. She’s a biologist at Washington State University. Her lab keeps a colony of bats.

Many bats sleep in caves and zoom around at night. Their world is dark, so they use sounds and their echoes to perceive the world around them, which is called echolocation. Toothed whales live in dark oceans or murky rivers and lakes. That’s why they use echolocation, too.

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What makes fireflies light up at night? – Asher, 7, Maryland

Dear Asher,

When I was a kitten, there were tons of fireflies in my grandparents’ yard. My litter mates and I loved to gently catch them and let them go.

I talked with my friend Richard Zack about how and why fireflies light up. He’s an insect scientist at Washington State University.

Those glowing insects are a kind of beetle. But we call them fireflies or lightning bugs. Their glow is a form of bioluminescence. That’s when a chemical reaction inside a living thing makes it light up.

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What are butterfly cocoons made of? — Anabelle, 8, Massachusetts

Dear Anabelle,

When I was a kit, I looked a lot like the adult cat I would become—even though I was smaller and fluffier. But wiggly caterpillars don’t look like butterflies at all.

I talked about this with my friend Allan Felsot. He’s an insect scientist at Washington State University.

He told me cocoons are mostly silk. But they’re usually made by moths. A butterfly “cocoon” isn’t really a cocoon at all. It’s called a chrysalis.

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Why do owls stay up at night? – Zelezina, 8 ½, Maryland

Dear Zelezina,

I love how humans use figures of speech about animals to describe their behavior. An early bird is someone who likes to get up early. A night owl is someone who loves to be awake late at night—like an owl.

I talked about why owls stay up all night with my friend Dr. Marcie Logsdon. She’s a wildlife veterinarian at Washington State University.

She told me that for many owls, the dark is a good time to catch a meal.

“Owls are just taking advantage of a time when they can excel at finding prey because there are a lot of other things that are active at night, too—like rodents,” Logsdon said.

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How does hair grow? – Aidric, 9, Ohio

Dear Aidric,

My whole body is covered in thick, glossy cat fur. Humans look mostly furless. But people grow hair on every part of their bodies except the palms of the hands and soles of the feet. Most human hair is just super fine and hard to see.

That’s what my friend Edward Johnson told me. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

He also told me hair grows from follicles. Those are special organs in the top layer of the skin. Everything you need to grow hair is inside the follicle.

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Why don't birds get electrocuted when they sit on power lines? – Angel, 14, California

Dear Angel,

I’ve never sat on a power line. I like to keep my paws firmly on the ground. But birds love resting there, especially in winter. Power lines give off a little heat, so it’s a good spot for birds to snuggle together and stay warm.

I talked about how they do that safely with my friend Javier Guerrero. He’s a professor of electrical and computer engineering at Washington State University.

He told me birds do get electrocuted on power lines sometimes. But that won’t happen if the bird touches just the power line—and doesn’t touch other lines or the pole at the same time.

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Why do dogs have tails? – Bailey, 7, Ohio

Dear Bailey,

My best friend is a golden retriever. When I get home, she greets me with a goofy smile and a big wag of her fluffy tail.

I talked about why she has a tail with my friend Jillian Haines. She’s a veterinarian at Washington State University.

She told me dogs use their tails for lots of things. Tails help dogs balance while running, jumping or swimming. Tails help dogs communicate with each other and other animals. Some dogs in the Arctic—like sled dogs—use their tails to stay warm. They curl up and cover their noses with their fluffy tails.

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Why do we get rashes on our skin? – Claire, 9, Virginia

Dear Claire,

I’ve been allergic to fleas ever since I was a kitten. Flea bites give me an itchy, red rash.

I talked about why that happens with my friend Bevan Briggs. He’s a nurse practitioner and professor at Washington State University. Nurse practitioners are nurses with advanced training. They diagnose illnesses, order tests and prescribe medicine.

Briggs told me that often rashes happen when the immune system gets turned on. The immune system is the body’s defense system.

“It's the way our body tries to protect us from germs and poisons,” he said. “Rashes happen because your immune system identifies something as foreign—either an infective agent or some kind of toxin.”

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Why do all insects have six legs? – Charlie, 10, Ohio

Dear Charlie,

There are about 40 kinds of cats out there—like me. There’s only one kind of human on Earth now. But there are more than a million kinds of insects. That’s just the insect species we know about.

Every single one of those insects has six legs.

I talked about why that is with my friend Allan Felsot. He’s an insect scientist at Washington State University.

He told me there must be some evolutionary reason insects have six legs—like better stability when walking.

“In biology, every ‘why’ question has the same answer,” Felsot said. “Things are the way they are because of adaptations that have allowed organisms to live longer.”

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Do fish and sharks drink water? – Copper, 9, Florida

Dear Copper,

All living things need water. It’s how life works on Earth. But do animals that swim in water drink water?

I talked about that with my friend Nora Hickey. She’s a fish veterinarian at Washington State University.

She told me it depends on the kind of fish. Saltwater fish constantly drink water. Freshwater fish drink hardly any water.

It’s all about the salts inside their bodies. Those salts make their muscles and nervous systems work.

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Who invented the calendar? – Audrey, 9, Oregon

Dear Audrey,

I use a calendar to keep up with my work as a science cat. I also love calendar apps that count down to big events—like my birthday. People have always tracked time for work and holidays.

I talked about this with my friend Nikolaus Overtoom. He’s a professor of ancient history at Washington State University.

He told me we use the Gregorian calendar today. That's a revised version of the Julian calendar. The Romans invented the Julian calendar.

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What diseases spread on pirate ships? – Anika, 9, Georgia

Dear Anika,

A pirate’s life was dangerous. They attacked other ships and battled other pirates as well as the law. But they were also at the mercy of another foe: sickness.

I talked about this with my friend Lawrence Hatter. He’s a history professor at Washington State University.

He told me the big era for pirates was 1710 to 1730. It was a time when lots of sailors were out of work. Some of them became pirates.

Here are four kinds of disease they might face on the job: scurvy, mosquito-borne diseases, infectious diseases and gangrene.

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Why do babies cry? – Camren, 7, Indiana

Dear Camren,

I was a very quiet kitten. I only cried when I needed something. But some kittens in my litter cried all the time.

I talked about this with my friend Masha Gartstein. She’s a psychology professor at Washington State University. She studies how babies develop different temperaments. That’s how you relate to the world around you in a way that’s unique and fairly consistent.

Gartstein told me babies cry because they’re helpless. They need a way to signal that they need something.

“Babies are born into this world needing a lot of assistance—and without a lot of communication tools,” she said. “Crying is a very powerful communication tool.”

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What organisms do you think would survive an apocalypse of extreme radiation? – Marshall, 11, New Zealand

Dear Marshall,

Sometimes I get x-rays at the veterinarian. They work by sending a small amount of powerful energy—called radiation—through my body. X-rays only contain a small amount of radiation. Too much radiation would harm my cells.

The organisms most likely to survive extreme radiation might be microbes. These creatures are so tiny you need a microscope to see them.

To learn more, I talked with my friend Cynthia Haseltine. She’s a microbiologist at Washington State University. She studies extremophiles. These microbes love intense environments. Boiling heat? Freezing cold? Blistering acid? Yes, please.

Haseltine told me the amount of radiation an organism can survive is measured in grays. Just 5 grays of radiation will kill a human. Here are five organisms that can survive way more than that.

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Why do crickets make sound? – Carola, 7, Virginia

Dear Carola,

Have you ever read the book “The Very Quiet Cricket?” It’s about a young cricket who can’t chirp until he grows up.

My friend Rich Zack reminded me of that book when we talked about your question. He’s an insect scientist at Washington State University.

He told me only adult male crickets make sound. Sometimes they chirp to defend their territories. It’s how they tell other male crickets to stay away.

But the main reason they chirp is to find a mate. Cricket chirps are mating songs. That song will be different for different kinds of crickets—and the song changes when the female cricket shows up.

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