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Ask Dr. Universe Plants, Animals, Microbes
University Communications Network > Ask Dr. Universe > Plants, Animals, Microbes

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 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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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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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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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 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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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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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 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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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 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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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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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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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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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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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 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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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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I want to know how snake venom in the antidote makes sense? – Raagini, 10, New York

Dear Raagini,

One of my roommates is a corn snake named Buddy. He’s not venomous. But he’s a very private individual and really likes his space.

Buddy and I talked about your question with my friend Blair Perry. He’s a biologist at Washington State University. He’s an expert on snakes and venom.

Perry told me antivenom doesn’t contain actual snake venom. It’s made with antibodies to snake venom.

Antibodies are proteins. They’re part of your immune system. They travel in your blood to fight germs or dangerous molecules—like those in venom—that could hurt you. Sometimes we get vaccines to boost our antibodies so they’re ready when something harmful shows up.

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Do insects have blood in their bodies? – Raman, 7, Washington

Dear Raman,

You probably don’t look like an insect. You don’t have feelers or wings. You keep your skeleton inside your body instead of on the outside. But what about blood? Do insects have blood like yours?

I talked about this with my friend Richard Zack. He’s an entomologist at Washington State University.

“Insects have hemolymph,” he said. “It’s very similar to blood.”

Zack told me hemolymph moves differently through the body, and it doesn’t do everything blood does.

Humans and other mammals have closed circulatory systems. That means their blood travels in blood vessels. A heart pumps the blood all over the … » More …

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How do you tell if your betta fish is happy or depressed? – Neely, 10, Oregon

Dear Neely,

As a science cat, I handle going to the veterinarian better than most. I see it as a meeting of scientific minds. But I had no idea some veterinarians specialize in fish.

I learned all about fish medicine from my friend Nora Hickey. She’s a fish veterinarian at Washington State University. She works in the Washington Animal Disease Diagnostic Laboratory. She helps fish at zoos and hatcheries stay healthy.

Hickey told me you can watch a betta's behavior to see if it's happy. Happy bettas swim around. They interact with things in their tanks and act interested when you come close.

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Are unicorns real? – Emma, 8, Minnesota

Dear Emma,

My favorite animated GIFs are the ones with cats riding unicorns. I’m delighted to tell you about a real unicorn that lived a long time ago: the Siberian unicorn.

The Siberian unicorn was bulky and furry. It had a big hump on its back. Its horn was three feet long. That’s as big as a human preschooler!

This real-life unicorn was a kind of rhino from Eurasia. But it was bigger than modern rhinos and probably galloped like a horse.

Scientists have known about Siberian unicorns since 1808. For a long time, they thought the unicorns went extinct 200,000 years ago. Recently, that changed. Now they think the unicorns went extinct closer to 39,000 years ago.

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How does evolution work? – Aubree, 10, Kentucky

Dear Aubree,

When I thought about evolution, I always pictured big changes that happened over long time periods—like how birds evolved from dinosaurs.

But then I talked with my friend Jeremiah Busch. He’s a biologist at Washington State University. He told me evolution is happening all the time.

“As soon as you see that evolution is occurring around us, it changes the way you think about the world,” Busch said.

There are a few ways evolution happens. These include mutation, gene flow, genetic drift and natural selection.

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Do ants hibernate in the winter? – Garrett, 10, Illinois

Dear Garrett,

When most people think about hibernation, they picture bears snoozing away the cold winter in their dens. You’re right that other animals do that, too.

I talked about your question with my friend Laurel Hansen. She’s an entomology professor at Washington State University. Her specialty is carpenter ants.

“We think most ants in our temperate climate will have diapausing larvae and what I would call overwintering adults,” Hansen said.

Diapausing and overwintering are like hibernating but not quite the same. There are a few things to know about ants to understand what these terms mean.

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How many beetles are there in the world? – Tu, 12, Utah

Dear Tu,

If beetles seem to be everywhere, that’s because they are. Some beetles stand out because they’re colorful. Think about jewel beetles and ladybugs. Others play useful and weird roles in the ecosystem—like the poop-rolling dung beetle. Their ancestors probably even ate dinosaur poop.

Nobody knows exactly how many beetles there are, but scientists have some ideas. I talked about it with my friend Joel Gardner. He’s the collection manager for the insect museum at Washington State University.

When scientists find a new species, they describe what it looks like. They give it a name. They publish that information so other people know about it. That’s called describing a species. Scientists describe new insect species all the time.

Gardner told me scientists have described about 400,000 species of beetles so far. There are many more beetles we don’t know about yet. Altogether, there are probably between 1 million and 2 million beetle species.

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Did dinosaurs eat humans? – Brileigh, 10, North Carolina

Dear Brileigh,

If you looked inside a T. rex mouth, you’d see some 12-inch teeth. That’s longer than my tail!

I asked my friend Aaron Blackwell if dinosaurs used those big chompers on humans. He’s an anthropologist who studies human biology at Washington State University. He told me dinosaurs and humans didn’t live at the same time.

“Dinosaurs died out 65 million years ago—before there were even primates,” Blackwell said. “So, they could never have eaten a human or even a monkey.”

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What if there were no predators to eat the birds? – Katy, 10, Hawaii

Dear Katy,

Don’t let the lab coat fool you. I enjoy chattering at birds as much as the next cat. Staring out the window and vibrating my mouth to “chirp” helps me relax after a long day.

My wild cousins do take things a bit further—namely, predation. It’s not pretty, but it’s an important part of keeping life in balance.

I talked about predators with my friend Travis King. He’s a Ph.D. student at Washington State University. He studies big cats like lynx and jaguars.

“It's a balancing act between predators, disease, food and space,” King said. “If you take away predators, you lose one of the factors keeping an ecosystem in balance.”

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Is it true that seven human years equals one dog year? – Cameren, 12, Kentucky

Dear Cameren,

Humans have kept dogs as pets for more than 14,000 years. That close friendship inspires scientists to explore questions like yours.

I talked about how dogs age with my friend Ryan Baumwart. He’s a heart doctor for dogs. He teaches in the veterinary hospital at Washington State University.

I asked Baumwart if a dog year is equal to seven human years.

“I think it's a good general rule,” he said. “But some larger breed dogs like bullmastiffs and Great Danes have a shorter lifespan of 6 to 8 years. So if you do the math, they get shorted. Then some small breed dogs like Chihuahuas seem to live forever.”

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How do animals teach their kids how to survive if animals can't talk? — Riley, 11, Texas

Dear Riley,

There’s really nothing cuter than baby animals. Many animal parents invest lots of time into caring for their young and teaching them to survive.

I talked about your question with my friend Amber Adams-Progar. She’s an animal sciences professor at Washington State University. She’s also an expert in dairy cow behavior. She told me that non-human animals learn in ways that are like how humans learn.

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If an animal has poison inside them, how are they not affected by their own poison? – Jad, 10, Georgia

Dear Jad,

From jellyfish to snakes to spiders, lots of animals use poison or venom. It helps them catch prey and defend themselves. Even the platypus and one very spicy primate called the slow loris use venom.

I talked about your question with my friend Blair Perry. He’s a biologist at Washington State University. He’s also a snake expert.

Perry told me the difference between poison and venom. They’re both toxic mixes of mostly proteins. But they get into your body in different ways. Poison is eaten, breathed in or absorbed through the skin. Venom is injected through a bite or sting.

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Do animals have religion like humans? – Anna, 12, Hong Kong

Dear Anna,

When I read your question, I thought about elephants. There’s evidence that elephants have complex emotions—like grief when their relatives die or affection for humans who help them. Whales, dolphins, non-human primates and even dogs sometimes seem like they have complex emotions, too.

It makes us wonder if animals seek comfort and meaning the same ways humans do—like through religion. We truly don’t know the answer to your question. It’s something people have wondered about for a long time.

Exploring deep questions is the work of my friend Joe Campbell. He’s a philosopher at Washington State University.

We often think of religion as beliefs and behaviors. They relate to the supernatural—something beyond us and what we see in the natural world.

Campbell told me that underneath many religious beliefs and behaviors is a feeling: awe. It’s a proto-religious attitude. Proto means first.

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How do starfish eat? – Hailey, 7, Maryland

Dear Hailey,

Starfish might have the coolest—and strangest—way of gobbling up a snack.

I learned all about it from my friend Cori Kane. She studied coral reefs when she was a biology Ph.D. student at Washington State University. Now she works for the National Oceanic and Atmospheric Administration. She writes policies to help protect the ocean and the animals that live there.

“Sea stars are probably one of the weirdest creatures. I don't know any other organism that basically barfs out its stomach to eat,” Kane said.

Yes, you heard that right. She said sea stars barf out their stomachs.

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Do animals feel home-like in wildlife sanctuaries? – Haniya, 8, Pakistan

Dear Haniya,

There are lots of things that make a place feel like home. Your home is probably full of sights, sounds and smells that feel familiar and cozy. Those things are important for animals in captivity, too.

To find out more, I talked with Charles Robbins, a wildlife biologist at Washington State University. He started the WSU Bear Center. It’s the only grizzly bear research center in the United States.

“The most important thing to bears and probably most animals is a feeling of safety—that they’re not being hurt, and the food is good,” Robbins said. “Probably all the same things that … » More …

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When was the first bee made? – Henry, 7, Illinois

Dear Henry,

It’s easy to love bees. They’re furry and buzzy. Along with other insects, birds and bats, they pollinate about one-third of the plants we eat.

I talked about how long bees have been buzzing around Earth with my friend Silas Bossert. He’s an evolutionary biologist in the Department of Entomology at Washington State University.

“The oldest bee fossil that is really without doubt a bee is between 65 and 70 million years old,” Bossert said.

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How does honey last forever? Gillian, 7, Illinois

Dear Gillian,

Archaeologists exploring ancient Egyptian tombs sometimes find honey. It’s thousands of years old, but you could still safely spread it on your toast!

I talked to my friend Brandon Hopkins, professor in the WSU department of entomology, about why honey lasts so long. He told me honey is one of the only foods that never spoils.

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What is octopus ink? – Henry, 6, Maryland

Dear Henry,

An octopus has three hearts and long arms with suction cups. It probably seems very different from you. But you have the main ingredients of octopus ink in your body, too!

I talked about octopus ink with my friend Gretchen Rollwagen-Bollens, associate professor in WSU’s School of the Environment. She told me that ink isn’t just an octopus thing. Most animals called cephalopods (sef-uh-luh-pods) make it. These include octopus, squid and cuttlefish.

Cephalopods including octopuses use color a lot. They have sacs of colored pigments all over their bodies. They use those sacs to change their body color. That helps them blend into their environment.

They also make and store a dark pigment in special ink sacs.

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Dr. Universe: Do spiders sleep? - Peter, 10, South Dakota

Dear Peter,

At the end of the day, you probably curl up in a cozy bed for a little shut eye. Unlike you, most spiders have eight eyes, and they never shut any of them. They don’t even have eyelids!

I talked about spider sleep with my friend Richard Zack, an entomologist and professor in WSU’s College of Agricultural, Human, and Natural Resource Sciences. He also runs the biggest insect museum in the state of Washington at WSU. He told me that spiders and insects do rest. They nestle into a safe spot and enter a “stupor,” which means they’re very still.

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Dr. Universe: How are sea animals affected by water pollution? - Natalia, 10, Florida

If you ever visit the beach, take a look at all the animals: crabs scuttling across the sand, seals bobbing on the waves and sea stars tucked into tide pools. Maybe there are even whales spouting on the horizon. Earth’s oceans are home to thousands of creatures. But, as you know, human pollution reaches our waterways and all the animals that live in them. To learn more, I talked to my friend Erica Crespi, an associate professor in the Washington State University School of Biological Sciences. Crespi studies how animals that live in water respond to all kinds of stresses, including pollution. Read More ...

Dr. Universe: When would a clam open its shell? Why do the shells open? As far as I know, it opens when boiled for food. - Teng, 5, China

Dear Teng, There are a lot of different reasons why a clam might open its shell. My friend Jonathan Robinson, a marine ecologist at Washington State University, told me all about it. If we spent some time where the ocean meets the shore, or the intertidal zone, we might observe how clams open their shells when they need to eat, breathe or move around. Read More ...

Dr. Universe: Why do trees grow so slow? – Ana, 7, Covert, MI

When you eat food, you get a lot of important nutrients that help you grow. The trees that live on our planet also need some nutrients to grow. Trees use their leaves to help capture energy from the sun to make their own food. But as you may have noticed, a lot of trees lose their leaves during certain times of the year. Without leaves, they can’t make nearly as much food, and without those important nutrients, they can’t grow very fast. That’s what I found out from my friend Tim Kohlhauff, a certified arborist and urban horticulture coordinator at Washington State University. He is very curious about the lives of trees. Read More ...

Dr. Universe: How do worms help protect the dirt? -Fisher, 7, Palouse, WA

Dear Fisher,

Worms can help the soil in a few different ways. One helpful thing worms do is move around different materials, such as leaves and grasses, and make holes in the soil. That’s what I found out from my friend Lynne Carpenter-Boggs, a soil scientist at Washington State University, who was happy to help with your question. Lynne Carpenter-Boggs “Worms are actually very strong,” Carpenter-Boggs said. “They can break through soil and make holes that allow air, water and plant roots to follow those channels.” Read More ...

Dr. Universe: How do horses sense how you feel? –Taylor, 11, New Zealand

When I got your question, I called up my friend and veterinarian Dr. Macarena Sanz who had just finished checking up on the horses at the Washington State University Teaching Hospital. She was happy to help. “It’s a hard question to assess scientifically,” Sanz said. “But I think everybody who has worked with horses can tell you that horses really do have a certain sense about humans.” Read More ...

Dr. Universe: How do trees give us air to breathe? – Jamar, 11, Vineland, New Jersey

Our planet is home to all kinds of different plants, and they help make a lot of the oxygen we breathe. To find out how plants make oxygen, I asked my friend Balasaheb Sonawane. Sonawane is a scientist at Washington State University who researches photosynthesis, or the ways plants use energy from the sun and make oxygen. He said that in a way, plants breathe, too. “They don’t have a nose or mouth,” Sonawane said. “They have tiny microscopic organs on their leaves called stomata.” Read More ...

Dr. Universe: Do flying squirrels really fly? - Gwendolyn, 9

Flying squirrels may not really fly, but they do have flaps of skin on their bodies that act like parachutes and help them glide through the air. My friend Todd Wilson told me all about it. He’s a wildlife biologist with the U.S. Forest Service in Oregon and graduate of Washington State University who researches Pacific Northwest ecosystems and the animals that call them home— including flying squirrels. Read More ...

Dr. Universe: Why do trees have sap? -Aliyah, 8, Kirkland, WA  

Just as blood moves important stuff around the human body, sugary sap moves important things around a tree. My friend Nadia Valverdi told me all about it. She’s a researcher at Washington State University who studies how apple and cherry trees survive in different environments. When we eat food, like a delicious apple or a handful of cherries, we get important nutrients. Read More ...

Dr. Universe: Why do mushrooms grow in rings? We have a lot of giant ones in our yard right now! - Layne, 8, Spokane 

When you see a ring of mushrooms, it’s likely they are exploring for food under the ground. Giant mushrooms in your backyard are not animals or plants. They are part of another class of living organisms called fungi. But like you and me, they do need food to survive. That’s what I found out from my friend David Wheeler, an assistant professor at Washington State University, who knows a lot about fungi. He said the mushrooms are just one part of fungi. The other part that explores the soil for food actually lives under the soil. Read More ...

Dr. Universe: Why do apes walk on their knuckles? - Sam, 10, Benton, Arkansas

Dear Sam, A lot of apes walk on their knuckles. Gorillas, chimpanzees and bonobos use their knuckles for stability and balance. That’s what I found out from my friend Nanda Grow, an anthropologist and wildlife biologist at Washington State University who studies primates. “Gorillas and chimpanzees both do knuckle walking, but they do different kinds,” she said. Read More ...

Dr. Universe: What are bees’ wings made of? -Natalia, 13, Kennewick, WA

Dear Natalia, Bee wings may be small, but they are really strong. I learned all about bee wings from my friend Melanie Kirby, a honey bee researcher at Washington State University. Kirby said you can think about bee wings as if they were a kite. If you make a kite out of thin tissue, it might rip. But if you make it out of a strong plastic film it will be stronger. Bee wings are made of a material called chitin (KITE-IN) and it’s a lot like keratin, the material that makes up your fingernails. Chitin is what makes up the wings on each side of the bee’s body. Read More ...

Dear Dr. Universe: I am wondering if birds can smell because I have chickens and have seen their nostrils! –Lila, 9, Philadelphia, PA

Birds have nostrils, or nares, on their beaks that can help them smell all kinds of things. That’s what I found out from my friend Dave Oleyar, a scientist with HawkWatch who recently taught a course on ornithology at Washington State University. He said that when an animal breathes air, they can also breathe in different scents or combinations of molecules. The nose has receptors that pick up on scents and send information to the brain, including a part called an olfactory bulb. It’s all part of the olfactory system. You have an olfactory system, too. This system can help animals navigate the world through a sense of smell. Read More ...

Dr. Universe: Why do some birds cheep loudly while other birds cheep quietly? -Traver, 4, Indiana 

That’s a great observation. Birds make all kinds of sounds and for lots of different reasons. When I got your question, I called up my friend Jessica Tir, a graduate student at Washington State University who studies songbirds. She said one of the main reasons a bird will make a loud sound is to attract a mate. When the birds find each other, they can make a nest for their eggs and wait for babies to hatch. Read More ...

Dr. Universe: What gives leaves their shapes? Please reply back. Thanks a ton! -Pronoy, 9, San Jose, CA, USA

We can find all kinds of leaves on our planet. Just think of tiny pine needles, fern fronds, ivy vines, or a big banana leaf. My friend Eric Roalson is a professor at Washington State University who is very curious about plants. He said there are a few things that give leaves their shapes. The shape of a leaf can depend on the family history of a plant, the group it belongs to, and the environment where it grows up. Read More ...

Dr. Universe: What is inside a blade of grass and why is it green? Green is my favorite color. We really like reading your articles in our newspaper. – Luke, 5, Ogden, Utah

Dear Luke,

I’ve been wondering the same thing lately.  Every time I go on walks, I notice new splashes of color. Watching bugs in the grass, I pretend they’re crawling through a jungle. Everything is bright and bursting with green.

When I saw your question, I knew Michael Neff would know the answer. Green is his favorite color, too. (In fact, when we talked over video, he wore a green Hawaiian shirt.) Neff researches plants at Washington State University, and he is especially curious about grasses.

If you chopped a piece of grass and looked at it with your eyes alone, you might not see much. But if you looked at it under a microscope, you’d see tiny structures containing even tinier parts.

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Why are carrots orange? - Caden, 11, N.C.

Dear Caden,

When you picture the carrot section at a grocery store in the United States, you probably imagine rows of orange. But carrots can come in a rainbow of other colors: purple, yellow, red, and more.

And the first carrots weren’t orange at all. They were stark white.

That’s what I learned from Tim Waters, a Vegetable Specialist at Washington State University-Extension. He studies how to grow different kinds of vegetables, and helps others learn how to grow them too.

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Dr. Universe: how do sleeping darts work? (e.g. for elephants) - Jonathan, 7, Pullman, Wash.

Dear Jonathan,

Some people get nervous when they go to the doctor. Maybe you’re one of them. You may not enjoy all of the visit, but you understand the doctor wants to help you. (And that a treat might await you at the end.)

But if an elephant gets sick, they can’t understand a doctor’s words. They may get confused and scared, until it’s too dangerous to help them.

That’s why sleeping darts—also known as tranquilizer darts—help so much.

“It’s safer for both the humans and the elephant because the humans aren’t right next to a wild animal, and the animal isn’t being chased to try to catch it,” Dr. Tamara Grubb said. She is a veterinarian at Washington State University who specializes in anesthesiology, drugs that make animals calm, sleepy, or unable to feel pain.

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How are seashells formed? And why are they different colors? Can seashells live or die? - Caroline, 9, Crestwood, Ky.

Dear Caroline,

Seashells come in an astounding variety. Some are curved and round, others long and tube-like. Some are smooth, others bumpy. Some are large, others small. Plus, they come in a rainbow of colors: red, green, brown, purple, pink, and more.

All that variety comes from the same source: little animals called mollusks, with a mighty muscle called a mantle.

I found out all about them from my friend Richelle Tanner, a scientist at Washington State University. She is very curious about the ocean and knows a lot about mollusks, a type of animal with a soft, moist body.

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Why won’t a female sea turtle lay her eggs in the ocean? How do baby turtles know where the ocean is when they hatch from their eggs? - Jasmine and Shereen, 8, Gainesville, Fla.

Dear Jasmine and Shereen,

Sea turtles spend almost their entire lives in the ocean. Even as babies, sea turtles’ bodies have special traits for living at sea, helping them glide and paddle through the water. After emerging from their eggs, baby sea turtles (called “hatchlings”) scramble to the ocean to live the rest of their lives. Only female sea turtles return to land as adults, to lay eggs and begin the cycle again.

I talked with my friend Frank Paladino to learn more about sea turtles. He completed his Ph.D. at Washington State University. Today he is a professor at Purdue University-Fort Wayne and former president of the International Sea Turtle Society. He is especially interested in leatherbacks, the largest living turtle.

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Dr. Universe: Do trees still create oxygen and clean the air after their leaves fall off? – Nova, 8, Palouse, Wash.

Dear Nova,

The trees that lose their leaves in fall, such as chestnuts, oaks, aspens, and maples, are called deciduous trees. Once they lose their leaves, most aren’t able to take in carbon dioxide gas from the air or produce any oxygen.

That’s what I found out from my friend Kevin Zobrist, a professor of forestry at Washington State University.

“Don’t fret, though,” Zobrist said. “For they more than make up for it in the summer.”

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Dr. Universe: Why are evergreen trees green all year? – Emily, 10, Silverdale, Wash.

Whenever I go for a hike in the woods, I can’t help but admire the tall evergreen trees. No matter what time of year it is, the pines, hemlocks, cedars, and spruces are usually all green. My friend Bert Cregg is also very curious about the lives of trees. He graduated from Washington State University and is a professor at Michigan State University. Read More ...

Dr. Universe: If snakes smell with their tongues, what do they do with their noses? – A.J., 5, Kennewick, WA

You’re right, snakes have an amazing sense of smell. They can use their tongues to pick up on all kinds of scents in the air. Whenever we smell something in the air, we are actually sniffing tiny building blocks called molecules. These molecules are what make up the scents of everything around us—things like baked bread, fresh-cut grass, and warm cookies. If you were a snake, you might sniff out the scent of a slug or mouse. You’d use your tongue to pull the molecules from the air into your mouth. Read More ...

Dr. Universe: How did the first horse change into the horses of today? -Ava, 7, Kennewick, Wash.

We can learn a lot about animals of the past from fossils, the imprints or remains we find in rocks. One fossil found in the Bighorn Basin, Wyoming helped us learn about the oldest known horses. These horses are called Sifrhippus (siff-RIP-us). They had four toes on each foot and were very small. Believe it or not, these tiny horses weighed only about ten pounds. That’s just a bit heavier than your average house cat. According to the fossil records, Sifrhippus lived somewhere between 54 and 30 million years ago. When I went to visit my friend Lane Wallett, she told me all about the history of horses. As a veterinarian and a paleontologist at Washington State University, she is very curious about both horses and fossils. Read More ...

Dr. Universe: How do trees help the air? – Ella, 12

Take a big, deep breath. As you inhale and exhale, you can probably feel the air taking up space in your lungs. The air we breathe is made up of a few different things. It includes gases such as nitrogen, oxygen, and carbon dioxide—just to name a few. Animals breathe in oxygen and breathe out carbon dioxide. But in the plant world, it’s the opposite. Trees, plants, and even algae in the ocean, take in carbon dioxide from the air and, using the energy of the sun, transform it into the oxygen we all breathe. Read More ...

Dr. Universe: Why are dogs important to humans? Stephani R., 9, Washington State

Dear Stephani, Dogs are important to humans in all kinds of ways. The connection between the two goes back thousands of years. A long time ago, wolves would trail along after humans on hunting trips and eat any scraps they could find. Eventually these wolves evolved into dogs that helped protect the hunters and gatherers. Read More ...

Dr. Universe: What can I do to help stop ocean pollution? -Hailey, 10

It’s great to hear you want to help our oceans. After all, they do a lot for us. Life in the ocean provides much of the oxygen we breathe and is also a source of food for many animals, including humans. One of the most important things we can do to prevent more pollution is to keep our garbage, especially plastic, out of the ocean. That’s what I found out from my friend Richelle Tanner, a marine biologist and researcher at Washington State University. While a lot of plastic ends up in the ocean, it actually started under the Earth’s surface in the form of oil, leftovers of plants and animals that died long ago. Read More ...

Dear Dr. Universe: Why do flowers smell so nice? – Miles, 5

Flowers not only smell nice to humans, but also to many insects and birds who help the flowers do a really important job. Let’s imagine that you are a bee or a butterfly. You don’t have a nose on your face, but instead use your two antennae to smell things. As you fly around, you catch a whiff of chemicals floating in the air. Down below, you see a field of daisies. The flowers are releasing some chemicals, which are the building blocks of a smell. Read More ...

Dear Dr. Universe: How many different types of plankton are there? Are there freshwater plankton? – Arielle, 11

We can find millions and millions of plankton in bodies of water all over the world—from oceans, rivers, and lakes to ponds and mud puddles. That’s what I found out from my friend Julie Zimmerman, a scientist with the Aquatic Ecology Lab at Washington State University. In the lab, researchers can use powerful microscopes to get an up-close look at these tiny creatures. Read More ...

Dr. Universe: What is the most smelliest fruit in the world? -Tiana, 9

Our world is full of fruits that have all kinds of delightful smells. Maybe you’ve smelled the sweetness of watermelon, pineapple, peach, papaya, or mango. But you might also be wondering about the most stinky fruit in the world. When I got your question, I asked my friend Lydia Tymon, a plant scientist at Washington State University. The first stinky fruit she thought of was the durian, a large, round fruit that grows mostly in Southeast Asia. The fruit is about a foot wide with a greenish-brown husk that has lots of spikes on the outside. Read More ...

Dr. Universe: How fast does a bunny hop? How long does a bunny live? Can a bunny swim? How many babies does a bunny have? -Rueben, 7, Pennsylvania

Bunnies are hopping all over our planet. Some hop through snow and deserts while others hop through wetlands and woods. There are lots of different kinds of rabbits and they are all a little different. For the most part, a bunny hops, or actually runs, anywhere between 25 and 45 mph That’s even faster than most house cats can run. Rabbits are related to another group of animals called hares. Actually, rabbits and hares are in the same family, Leporidae. Hares look a lot like rabbits, but they have much bigger ears and bigger feet. Read More ...

Why do lizards lose their tails? -Bailey, Inwood, Iowa

Dear Bailey,

Our planet is home to all kinds of lizards. Maybe you’ve seen one climbing up the wall, scurrying through the grass, or at the pet store. Just the other day I saw a big green iguana when I visited the Washington State University Veterinary Teaching Hospital in search of an answer to your question.

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Dear Dr. Universe: I have a question for you about ants. From what I searched on Google, an ant has a nervous system, blood, open circular system, muscles, and a brain. So, Dr. Universe, the question is, do ants or other insects get headaches? Cause they work hard. –Joseph, 14, Singapore

Dear Joseph,

If you’ve ever had a headache, it might have felt like pain was radiating right out of your brain.

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