Share

Why Though? with Dr. Matt Agnew
Do Fish Get Thirsty?
Fish spend their whole life in water. But do they actually drink it? Turns out the answer depends entirely on which fish you ask.
In this episode of Why Though?, Dr Matt Agnew dives into what thirst really is, why saltwater and freshwater fish handle water in completely opposite ways, and why sharks are the cleverest rule-breakers in the ocean. Plus a kid in a shark costume makes an appearance. Obviously.
What you'll learn:
- Thirst is your body's alert system... and your body is about 60% water
- Saltwater fish live in super salty water, so water leaks out of their bodies... they drink seawater to survive and their gills filter the extra salt out
- Freshwater fish have the opposite problem... water rushes into their bodies, so they barely drink at all and pee constantly to stay balanced
- Sharks keep a chemical called urea in their bodies that helps water flow in naturally through their skin and gills... no drinking required
- Sharks have been in the ocean for over 400 million years... longer than trees have existed on land
Key Science Ideas:
- Salinity: How salty water is
- Osmosis: Water moving from a less salty area to a more salty area through a membrane like skin or gills
- Homeostasis: Keeping the body's internal conditions just right so everything works properly
- Urea: The chemical sharks use to stay hydrated without drinking seawater
- Gills: A fish's built-in filter system for managing salt and water
Fun Experiment: The Gummy Bear Grow-Off Grab three cups and label them Fresh, Salty, and Super Salty. Add plain water to the first, two teaspoons of salt to the second, and four teaspoons to the third. Drop a gummy bear into each cup, make a prediction, then check back after two hours and again the next morning.
The fresh water gummy swells up the most as water rushes in. The salty one grows a little. The super salty one barely changes at all... the saltier the water outside, the less water moves in. That's osmosis... the exact same process fish use to manage water in their bodies every single day.
Treat the gummies as science props and wash hands after handling.
Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.
Follow Dr Matt Agnew:
Instagram: instagram.com/drmattagnew
TikTok: tiktok.com/@drmattagnew
YouTube: youtube.com/@whythoughpod
Website: drmattagnew.com
Find Why Though? podcast across the internet and share with your friends!
Instagram: instagram.com/whythoughpod
TikTok: tiktok.com/@whythoughpod
Facebook: facebook.com/whythoughpod
More episodes
View all episodes

5. Why Do My Dog's Paws Smell Like Doritos?
03:45||Season 1, Ep. 5Have you ever sniffed your dog's paws and noticed they smell kind of like Doritos? Not because your dog is secretly snacking on chips... because of something much more microscopic.In this episode of Why Though?, Dr Matt Agnew investigates the tiny living world on your dog's paws. What are bacteria and yeast? Why are dog paws such a perfect home for microbes? And what are they actually doing in there that smells exactly like corn chips?What you'll learn:Dog paws smell like Doritos because of tiny living things called bacteria and yeastDog paws are a perfect microbe home... warm, slightly moist, and picking up dirt and crumbs on every walkTwo bacteria called Proteus and Pseudomonas are usually responsible for that cheesy corn chip smellThe scientific word for this tiny community is the microbiome... and your dog has one living right on their pawsYour own body has trillions of bacteria... even more than human cellsThe Dorito smell is usually totally normal... but red, itchy or sore paws mean a trip to the vetKey Science Ideas:Bacteria: Single-celled organisms found almost everywhere, including on your dog's pawsYeast: A type of fungus... the same kind that helps bread riseMicrobiome: The community of tiny living things on and inside a bodyMicrobes: The scientific word for tiny living things like bacteria and yeastPseudomonas and Proteus: The two bacteria most responsible for that corn chip smellFun Experiment: The Microbe Hotel Take a small piece of bread and leave it in a warm, slightly damp spot for a few days. Watch what grows on it. That fuzzy stuff is mould... a close relative of the yeast living on your dog's paws. Warmth plus moisture plus a tiny bit of food equals microbes moving in. Sound familiar? That's exactly the same recipe as a dog's paw. Once you've had a good look, wrap it up carefully and pop it in the bin... don't open it indoors once the mould gets going.Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.Follow Dr Matt Agnew: Instagram: instagram.com/drmattagnew TikTok: tiktok.com/@drmattagnew YouTube: youtube.com/@whythoughpod Website: drmattagnew.comFind Why Though? podcast across the internet and share with your friends!Instagram: instagram.com/whythoughpodTikTok: tiktok.com/@whythoughpodFacebook: facebook.com/whythoughpod
3. Why Is Pluto No Longer a Planet?
04:24||Season 1, Ep. 3Pluto used to be the ninth planet in our Solar System. Then in 2006 everything changed. Dr Matt Agnew explains why... and it's a better story than you think.In this episode of Why Though?, we travel back to 1930 when astronomer Clyde Tombaugh spotted a tiny moving dot in the night sky and made one of the biggest discoveries in space history. We find out what happened when scientists discovered Eris... a Pluto-like world that was even heavier than Pluto. And we learn the three-rule checklist that decides what actually counts as a planet.Of course Matt's dog Pluto makes a cameo.What you'll learn:- Pluto was discovered in 1930 and taught as the ninth planet for over 70 years- Better telescopes revealed a whole region of icy worlds beyond Neptune called the Kuiper Belt- Scientists found Eris... similar to Pluto but even heavier, which forced a big question- To be a planet, a world must orbit the Sun, be round, and clear its neighbourhood- Pluto does two out of three... but it hasn't cleared its neighbourhood- Pluto became a dwarf planet in 2006... and it's still completely incredibleKey Science Ideas:- Kuiper Belt: A region beyond Neptune full of icy objects- Planet definition: The three-rule checklist astronomers use to classify worlds- Clear its neighbourhood: Being the gravitational boss of your part of space- Dwarf planet: Orbits the Sun, is round, but hasn't cleared its neighbourhood- Scientific change: Science updates its ideas when new evidence appearsFun Experiment: The Planet Checklist ChallengeScientists use a three-rule checklist to decide what counts as a planet. Now it's your turn to be the astronomer.Grab five objects from around the house... a footy, a mandarin, a marble, a 50 cent coin, and a tin of baked beans. These are your space objects. For each one, ask the three planet questions:- Does it orbit a star? Walk it around a lamp- Is it round? Check its shape- Is it the boss of its space? Could it push everything else out of its way, or does it have to share?Only objects that pass all three rules get to be a planet. Then here's the twist... change one rule and see what happens. That's exactly what scientists did in 2006. They didn't move Pluto. They just got clearer about the rules. And Pluto couldn't pass the third test.Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.Follow Dr Matt Agnew:Instagram: instagram.com/drmattagnewTikTok: tiktok.com/@drmattagnewYouTube: youtube.com/@whythoughpodWebsite: drmattagnew.comFind Why Though? podcast across the internet and share with your friends!Instagram: instagram.com/whythoughpodTikTok: tiktok.com/@whythoughpodFacebook: facebook.com/whythoughpod
2. Why Does Helium Make Our Voice Sound Funny?
04:32||Season 1, Ep. 2Ever heard someone talk after a helium balloon and suddenly sound like a tiny squeaky mouse? There's real science behind it... and it's weirder than you think.In this episode of Why Though?, Dr Matt Agnew investigates the helium voice mystery. Why do balloons float? Why does sound travel faster through helium? And how does all of that flip a normal voice into instant chipmunk mode? Plus we find out about a super-heavy gas that does the exact opposite... making voices go deep and booming. What you'll learn:Helium is less dense than air... that's why balloons floatYour vocal cords and throat work together to shape soundSound travels faster through helium, which shifts the way your voice soundsYour brain hears those shifted sounds as higher and squeakierScientists call the frequencies that shape your voice formants... helium scrambles themKey Science Ideas: states of matter, density, vocal cords, resonance, formants.Fun Experiment: Hum "mmmm" with your mouth closed then slowly open it wider. Hear the change? That's resonance in action... same science, no gas required.Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.Follow Dr Matt Agnew:Instagram: instagram.com/drmattagnewTikTok: tiktok.com/@drmattagnewYouTube: youtube.com/@whythoughpodWebsite: drmattagnew.comFind Why Though? podcast across the internet and share with your friends!Instagram: instagram.com/whythoughpodTikTok: tiktok.com/@whythoughpodFacebook: facebook.com/whythoughpod
1. Why Does Eating Ice Cream Too Fast Give Me a Headache?
03:54||Season 1, Ep. 1Ever bitten into ice cream too fast and felt a sudden sharp pain in your forehead? That's brain freeze... and there's real science behind it.In this episode of Why Though?, Dr Matt Agnew breaks down exactly what's happening inside your mouth and your brain when ice cream hits too hard and too fast. Why do your blood vessels squeeze and then suddenly open again? And why does your brain sometimes "feel" the pain in your forehead when the cold started on the roof of your mouth?What you'll learn:Brain freeze starts when something super cold touches the roof of your mouth, called the palateCold causes tiny blood vessels to squeeze tight... then open quickly as things warm upThat fast squeeze-and-open triggers pain sensorsYour brain can get tricked into feeling that pain in your forehead, even though the cold never got anywhere near itKey Science Ideas:Palate: The roof of your mouthBlood vessels: Tiny tubes that carry blood around your bodyVasoconstriction: Blood vessels narrowing when coldVasodilation: Blood vessels widening again as things warm upReferred pain: When your brain feels pain somewhere different from where it startedFun Experiment: The Brain Map Glitch Cross your index and middle fingers into an X. Close your eyes. Use your crossed fingertips to gently touch a grape or a pea. It'll often feel like two objects, not one. That's your brain's body map getting confused... just like brain freeze.Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.Follow Dr Matt Agnew: Instagram: instagram.com/drmattagnew TikTok: tiktok.com/@drmattagnew YouTube: youtube.com/@whythoughpod Website: drmattagnew.comFind Why Though? podcast across the internet and share with your friends!Instagram: instagram.com/whythoughpodTikTok: tiktok.com/@whythoughpodFacebook: facebook.com/whythoughpod
Why Though? is Coming Soon
01:44||Season 1, Ep. 0Hey! I'm Dr Matt Agnew and I've got a brand new podcast coming your way very soon.Why Though? is the show for kids who can't stop asking questions. And I mean the really good ones... why do dog paws smell like Doritos? Why are farts smelly? Do fish actually get thirsty?Every episode we take one big question and turn it into a science adventure. Weird facts, real answers, and stuff that'll make you see the world completely differently.Why Though? The show for little scientists who love asking big questions.Hit follow or subscribe now so you're first in line when Episode One drops.Follow Dr Matt Agnew:Instagram: @drmattagnewTikTok: tiktok.com/@drmattagnewYouTube: youtube.com/@whythoughpodWebsite: drmattagnew.com