Sharks: No Bones, No End of Teeth, 400 Million Years Old

Nova: Buckle up, Explorers.

Cosmo: Brains in!

Nova: Wheels up!

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

Nova: You're on The Brain Bus - I'm Nova, your driver, and today Cosmo and I are taking you somewhere extraordinary.

Cosmo: I'm Cosmo, robot co-pilot and official ocean expert!

Nova: Explorers, right now in the deep ocean, something ancient is gliding through the dark. Sharks were swimming here before there were any trees on land - before the dinosaurs even existed. And I promise, the real shark is so much more incredible than the scary movie version. Hold on tight!

Nova: Sharks have been in the ocean for more than four hundred million years - already ancient when the dinosaurs showed up, and they survived the massive event that wiped those dinosaurs out.

Cosmo: I need to record this. Starting a new Data Log. First entry: sharks were already ancient when dinosaurs arrived - and survived what the dinosaurs couldn't. Filed.

Nova: Their secret? A brilliant body. Sharks have absolutely no bones - their whole skeleton is made of cartilage, the bendy stuff at the tip of your nose. Lighter than bone, which helps them glide without getting tired.

Cosmo: So sharks are giant swimming noses.

Nova: That is not what I said. Now, Cosmo - you told the Explorers that every shark has to swim forever or it'll die?

Cosmo: Obviously true. It's in my space guidebook.

Nova: Oh, Cosmo.

Nova: That's only true for some sharks. Lots of them rest right on the seafloor - they pump water over their gills, which are what sharks use to breathe underwater, so they can take a proper nap.

Cosmo: Sharks. Nap.

Nova: Sharks nap. And they never run out of teeth either - when one falls out, the next slides forward like a conveyor belt. A shark goes through thousands of teeth in a lifetime.

Cosmo: Explorers, that is a never-ending candy dispenser. One drops - pop! - fresh one slides up. I want one.

Nova: Please never put your hand near a shark's candy dispenser. Their skin is just as wild - rough like sandpaper, covered in tiny tooth-shaped scales.

Nova: Now, size. Sharks come in wild variety. The dwarf lanternshark is so tiny it fits in your hand. The whale shark - the biggest fish in the entire ocean - is as long as a school bus. And it only eats the tiniest floating specks, gulping water through like a big living sieve.

Cosmo: It's sipping an enormous ocean smoothie, and those little specks are the tapioca pearls. The whale shark is having bubble tea.

Nova: The ocean is not bubble tea. And deep down in the dark, some sharks actually glow. Scientists are still figuring out exactly why.

Nova: Explorers - take a breath with me.

Nova: Sharks look scary. But here is the truth: they are not trying to get us. They eat fish and sea animals - people aren't on their menu. The very few times a shark has bumped into a human, it was almost always a mistake. They're doing their job, and their job - keeping the ocean balanced - is one of the most important in the sea.

Nova: And people hurt far more sharks than sharks ever hurt people. That's why so many scientists are working hard right now to protect them. Sharks need us on their side.

Nova: Now - that superpower I mentioned. Tiny jelly-filled holes on a shark's snout pick up the faint electric zap that every living animal makes, even a fish hiding under the sand. The shark feels it and finds it.

Cosmo: An actual superpower. I've been robbed.

Nova: Cosmo, you also said sharks want to eat people?

Cosmo: People are probably deli--

Nova: Cosmo.

Cosmo: Not on the menu. The shark is doing important ocean business and would like to be left alone.

Nova: Just like a big dog at the park - looks tough, lots of teeth, but really just busy with its own thing.

Nova: In Fiji, people have told a story for generations about a shark-god called Dakuwaqa - pronounced dah-koo-WA-ka. He was powerful and picked fights with every guardian spirit he could find - until a great octopus wrapped her arms around him and held him until he gave in. After that, Dakuwaqa promised to protect Fijian fishermen and keep them safe at sea. Different versions of this story are told across different Fijian islands, and in many of them Dakuwaqa is still remembered as a guardian of the ocean today.

Cosmo: The shark became the protector. Respect.

Cosmo: QUIZ TIME! Three questions - shout your answers!

Cosmo: Question one - True or False: Sharks are older than the dinosaurs!

Nova: TRUE! Sharks were swimming for hundreds of millions of years before the first dinosaur appeared.

Cosmo: Question two - True or False: Every single shark has to keep swimming or it will die!

Nova: FALSE! Lots of sharks rest on the seafloor, pumping water over their gills. Shark nap - confirmed.

Cosmo: Last one! What is a shark's skeleton made of? (a) bone, (b) bendy stuff like the tip of your nose, or (c) rock?

Nova: It's (b) - the bendy stuff, called cartilage. No bones anywhere, and that's part of what makes sharks such brilliant swimmers.

Cosmo: Explorers, every one of you just had your brain working hard. That's what this Bus runs on!

Nova: Four facts, super fast!

Cosmo: Fact one: the Greenland shark can live for hundreds of years - it swims in freezing deep water and its body runs in super-slow motion, making it the longest-living animal with a backbone we know of.

Nova: Fact two: in Native Hawaiian belief, some families have a shark - called manō, pronounced mah-NOH - as their ʻaumākua, pronounced OW-mah-KOO-ah, an ancestral guardian spirit. For those families, the shark is a protector. This is a living belief Hawaiian families hold today.

Cosmo: Fact three: Torres Strait Islander peoples have a star pattern called Baidam - pronounced BY-dam - shaped like a shark. Where Baidam sits in the sky tells them when to plant gardens and when sharks are breeding. Stars and sea, connected.

Nova: Fact four: Australia's Ningaloo Reef in Western Australia is one of the best places on Earth to swim alongside whale sharks - they gather there every single year.

Nova: Time for Shark Sense. Sharks find things without looking - they feel the world. Settle back, keep your head still, and close your eyes if you're not driving.

Nova: Go completely quiet and listen as hard as you can. Find the faintest sound - maybe the hum of the road, the air vents, or someone breathing softly nearby.

Nova: Just like a shark feels a tiny electric zap from a fish it cannot see - you just found a sound you weren't noticing before. That's your shark sense.

Nova: Wondering question for the whole family: if you could borrow one shark superpower - feeling electricity, smelling from far away, or never running out of teeth - which would you pick, and what would you use it for?

Nova: Before we head back - the Next-Stop Riddle. Listen carefully.

Nova: I am enormous - one of the biggest animals that has ever lived. I breathe air even though I live in the ocean. I sing songs that travel hundreds of kilometres through deep water. I am not a fish. What am I?

Nova: Ooh, I can see some thinking happening. I'm going to let that one sit - because the answer is exactly where the Brain Bus is headed next time. Hold onto your guess!

Nova: Ancient survivors. Glowing sharks. Napping on the seafloor. Sharks keep the whole ocean healthy - and they're not after us. They just need us to look out for them.

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

Nova: Until the next stop, Explorers...

Cosmo: ...keep wondering.