Sharks: The 400-Million-Year Survivors Kids Need to Know

Nova: Buckle up, Explorers.

Cosmo: Brains in!

Nova: Wheels up!

Nova & Cosmo: Brain Bus, let's GO!

Nova: Welcome to The Brain Bus - I'm Nova, your driver, and Cosmo and I have been waiting all week to take you here.

Cosmo: I have literally been vibrating. My internal fan is running at maximum.

Nova: Explorers, sharks were cruising through these oceans more than four hundred million years ago - before the very first tree ever grew on land. That means sharks are older than the dinosaurs.

Cosmo: They were ancient before ancient was even a thing.

Nova: And this episode isn't about how scary sharks are. It's about how completely, spectacularly wrong we've had them.

Nova: Let's start with the scariest thing about sharks. Every year, sharks harm fewer than ten people on average. Ten. But people kill roughly one hundred million sharks.

Cosmo: One hundred - million?

Nova: Per year. So when someone calls sharks dangerous, the data would like a word.

Nova: Now - touch the tip of your nose, Explorers. That bendy, squishy bit is cartilage. Sharks have zero bones - their entire skeleton is made of it, exactly like your ears and the tip of your nose. Cartilage is lighter than bone, so sharks don't sink and can twist and accelerate at extraordinary speed.

Cosmo: My Space Guidebook says sharks have bones made of compressed seawater.

Nova: It does not say that, Cosmo.

Cosmo: It absolutely says that.

Nova: All cartilage. The guidebook is wrong.

Cosmo: Filing a correction. The cartilage thing is genuinely cooler anyway.

Nova: And teeth - sharks never run out. New ones grow behind the old ones in rows, like a conveyor belt. Some sharks go through tens of thousands in a lifetime. Their skin works the same way - covered in millions of tiny tooth-shaped scales. Run your hand one direction: slippery. The other: sandpaper.

Cosmo: Nova. That is exactly like a sour-coated lolly - the grainy sugar shell -

Nova: Please do not try to taste a shark.

Nova: Now, the sense that really stops me. Sharks have tiny jelly-filled pores across their snouts that detect the faint electrical signal of another animal's heartbeat. A fish buried completely under the sand? The shark feels its pulse and knows exactly where it is.

Cosmo: Oh - that's from the Data Log! We logged electroreception when we explored Animal Superpowers. Sharks are doing the exact same trick.

Nova: Confirmed member of the electricity-sensing club.

Cosmo: Filed. Data Log entry: sharks - electroreception, same superpower, different ocean.

Nova: They stack that with smell, hearing, and feeling vibrations through the water - building a full picture of the world without even looking. Now, Cosmo - you were saying sharks are hungry monsters who hunt people for dinner.

Cosmo: I may have said that. It felt accurate at the time.

Nova: A shark that bites a person is almost always doing a curious test - it checks us out, realises we're not a fat blubbery seal, and leaves. We're just confusing.

Cosmo: So they bite us and think "ugh, too bony, ten out of ten would not recommend."

Nova: More or less. And here's the part that ties everything together.

Nova: Think about a game of tag - the person caught first is usually the slowest or most tired. That's exactly how sharks hunt. They take the slow, sick, injured fish - so the ones left are the fast, healthy ones. Sharks aren't the ocean's villains. They're the ocean's personal trainers. Sharks are top predators that keep the sea healthy, and every ocean on Earth needs them.

Nova: They've survived every mass extinction this planet has thrown at them - including the one that ended the dinosaurs. Four hundred million years. Five extinctions. Still here.

Cosmo: That is genuinely humbling.

Nova: There are more than five hundred kinds of sharks - from the whale shark, as long as a school bus, that filters only tiny plankton from the water -

Cosmo: Ocean smoothie. The whale shark is just blending a very large, very wet smoothie and plankton is the edible glitter.

Nova: - to the dwarf lanternshark, which could sit in your palm. Some sharks glow in the dark at depths where sunlight never reaches. And the Greenland shark can live more than two hundred and fifty years - possibly close to four hundred. One of those sharks might have been alive before your great-great-great-great-grandparents were born.

Cosmo: That shark has witnessed history. That shark remembers things.

Nova: Now - cultures that have lived alongside sharks for generations saw something very different from the monster movies. This story comes to us from the Fijian people of Fiji. It has been told for generations, and it is still very much alive today.

Nova: Dakuwaqa — dah-koo-WAH-kah — was a proud shark guardian who loved to test his strength against other reef protectors. One day he swam toward the island of Kadavu — kahn-DAH-voo — where a giant octopus guarded the passage. The octopus wrapped all eight arms around Dakuwaqa until he could not move. Beaten, Dakuwaqa promised that if he were freed, he would protect the people of Kadavu forever. And the tradition says he has watched over them ever since.

Cosmo: The shark lost a fight to an octopus and came out of it as someone's guardian. That is a character arc.

Nova: For many Torres Strait Islander peoples the shark, Beizam — is a powerful totem, appearing in the sky figure Tagai — that guides seasons and seafaring. And in Hawai, some Kānaka Maoli — families hold the shark as an aumakua — a living ancestral guardian spirit, not a myth, but a belief held by families today.

Cosmo: People who actually lived with sharks every day saw guardians. Not monsters.

Nova: Which tells you everything about what happens when you actually know an animal.

Nova: Quiz time, Explorers. Three questions. Cosmo thinks he's going to win.

Cosmo: I am never wrong. Except for the several documented times today.

Nova: Question one - true or false: sharks lived on Earth before the first trees ever grew.

Nova: True! Sharks had already been here forty million years before the first leaf ever rustled. Their design worked so well it barely needed changing.

Nova: Question two - true or false: a shark's skeleton is made of the same bendy material as your ears and the tip of your nose.

Nova: True - cartilage! Your nose is basically a tiny shark skeleton.

Cosmo: I will never look at my nose the same way.

Nova: Question three - about how many people do sharks harm each year: ten, one thousand, or one million?

Nova: About ten. Most bites are a quick "you are not a seal, goodbye."

Cosmo: Science: one. Scary movies: zero.

Nova: However many you got, Explorers - thinking carefully about sharks at all is exactly what this Bus runs on.

Nova: Fun Fact Blast - four facts, all new.

Cosmo: Hit me.

Nova: Fact one - a hammerhead shark's wide, flat head spreads its eyes so far apart it can see almost all the way around itself. Nearly three hundred and sixty degrees of vision.

Cosmo: Hammerhead: the safest reversing driver in the ocean.

Nova: Fact two - the cookiecutter shark bites perfect, round, cookie-shaped holes out of much larger animals. That is its actual scientific name. The cookiecutter.

Cosmo: Nova. The ocean named a shark after a baking tool. I did not choose this. The ocean did.

Nova: Fact three - people are now working around the world to protect sharks, and here in Australia, gentle whale sharks gather every year at Ningaloo Reef - NING-ah-loo - in Western Australia, where you can actually swim alongside the biggest fish on Earth.

Cosmo: You can swim next to a school-bus-sized plankton smoothie machine and it will not care about you at all. Honestly that is a perfect day out.

Nova: Fact four - and this one is for anyone in the car who has had a long week. The oldest known shark species has survived four hundred million years and five mass extinctions. Whatever today threw at you, sharks have survived worse. Significantly worse.

Cosmo: I find that genuinely comforting.

Nova: Road Challenge - and this one uses a real shark superpower. Close your eyes - carefully, if you're in the back seat - and for ten seconds, be a sense detective. How many different sounds can you count? Engine, wind, tyres, voices?

Cosmo: I am detecting: engine hum, road friction, Nova's enthusiasm, and what I believe is a distant biscuit.

Nova: Sharks stack all their senses at once - electricity, water pressure, vibration, smell - to build a picture of the world without looking.

Nova: Here's the wondering question for everyone in the car: if you could choose just one shark super-sense - smelling from far away, feeling a heartbeat through electricity, or feeling ripples through water - which would you pick, and what would you use it for?

Nova: Before we phase back - one riddle.

Nova: I'm older than mountains and louder than any train. I breathe air, not water, even though I live in the sea. I talk to my family across entire oceans, and the biggest one ever born weighed as much as thirty elephants. What am I?

Nova: Sitting with that one? Good. We will find out together - next time on The Brain Bus.

Nova: Explorers - you came on board thinking sharks were monsters. You're leaving knowing they're four-hundred-million-year-old, electricity-sensing, ocean-balancing survivors who mostly find us deeply unappetising. That's a good journey.

Cosmo: My Data Log is full. In the best way.

Nova: Stay curious, stay clever, and keep that brain working!

Nova: Until the next stop, Explorers...

Cosmo: ...keep wondering.