Quiz: how many hearts does an octopus have?

Who will win Naked Scientists' big brain of the week? Our teams are tech guru Peter Cowley and food security expert Nadia Radzman, facing off against neuroscientist Duncan Astle and engineer Lívia Ribeiro de Souza...

Peter and Nadia, you’re team 1. Duncan and Livia, you’re team 2. You’re competing for the honour of the naked scientists’ big brain of the week. Ready?

ROUND 1

There are three rounds - the first one is sci-fi or sci fact? And for this, we’re going under the sea...

So Peter and Nadia...

Q: Octopuses have 8 hearts, 1 that powers each tentacle. Science fact, or sci-fiction?

Nadia - I am not sure…

Peter - I’m sort of towards no.

Nadia - … I would say yes.

Peter - Okay, so we disagree. Is there a coin we can toss?

[Laughter in studio]

Chris - What are you going to go for, science fact with 8-hearts?

Peter - Nadia is going to answer it.

Nadia - It’s too many hearts on one organism, I would think.

Chris - So you think science fiction?

[Correct buzzer sounds]

It is indeed science fiction! They do actually have three hearts.

Peter - Per leg?

Chris - Ha ha, no that would be 18… Wait, 24! You’re testing my maths. Two of the hearts move blood through the animal’s gills, while the third keeps the organs perfused. The interesting thing is that the third organ perfusing heart actually stops beating when the animal swims, which is why they tend to slink around and crawl about. It's more efficient in terms of their circulatory demands.

So plus one to you two. Right, Duncan and Livia. You're up next.

Q: American explorer Victor Vescovo, during his descent to the bottom of the Mariana Trench, the deepest ever dive, found what?

A species of 12-eyed fish, since named decem-oculus pisces.
A cannonball fired from a military naval vessel thought to have participated in the Battle of the Java Sea.
A Tin of spam.

Or, all of the above?

Duncan - Naval History is not really my thing. The cannon ball seems plausible but…

Lívia - I feel like saying “all of the above” just to cover all of the options.
Duncan - I can imagine all of the above is true.

Chris - You’re going all of the above. Is that true or is it false? Well I'm afraid to say....

[Incorrect buzzer sounds]

No it's not true. The fish we made up. The cannonball? No idea but there might be one of those down there but he certainly didn't find it. He found a tin of spam.

You can look at the picture, it's really quite staggering. At five kilometres down, on the slope, on the way down into the Mariana Trench. Even deeper down he did find plastic bags, some sweet wrappers and some other angular metal objects, which we'll assume were human made. But no twelve-eyed fish or cannonballs I'm afraid, Duncan and Lívia.

So no points for you so far. Right round two, you're in the lead Peter and Nadia.

Q: Which is taller?  The Empire State Building in New York or the Shard in London.

Peter - The Empire State Building is about a thousand feet and I think the Shard slightly higher. My guess is it's probably about 10 to 30 metres higher.

Nadia - I’ll go with your answer.

Peter - I would say the Shard.

Chris - And the answer is....

[Incorrect buzzer sounds]

...No. New York has clinched it. The Empire State Building 381 meters the Shard is 310.

Peter - That's including the mast on the top though, isn't it?

Chris - Well I didn't say that! You're just getting desperate now, Peter. Okay, so zero for that round, Peter and Nadia are still on one.

Duncan and Lívia your chance to claw back the victory..

Q - Which has the fastest acceleration -  that’s nought to sixty… Or one hundred kilometres an hour for people on new money - a cheetah or a Ford Fiesta ST, that's a sports turbo Ford Fiesta? So what can accelerate nought to sixty the fastest, a cheetah or a Ford Fiesta ST?

Duncan - I used to have a Ford Fiesta…

Chris - Was it an ST though?

Duncan - No it wasn’t!

Chris - Hmmm, that's the difference. See I had a Ford Fiesta and it definitely was an ST.

Duncan - I know cheetahs are really quick.

Lívia - Yeah, I would guess cheetahs

Duncan - Nought to sixty… Sixty is quite fast for a cheetah to go.

Lívia - Cheetah.

Duncan - Yeah, we’re gonna go cheetah.

Chris - And the answer is…

[Correct buzzer sounds]

Yes, you’re plus now so it’s level pegging now so well done.

The cheetah is faster by far. The Ford Fiesta ST, the 2012 to 2017 model, is quoted to do 0 to 60 in 6.7 seconds, the cheetah achieves that in three.

Everyone - Wow.

Chris - It's elastic energy in tendons and muscles, it’s an explosive burst of speed. The acceleration, the rate of speed, changes very fast, much faster in the car. What the cheetah can't do is to keep it up for any duration. It can do that for a matter of seconds. The Ford Fiesta hopefully manages a little bit better than that.

Level pegging on round three… It’s all on this one. Otherwise, we go to tiebreaker. Back to you Peter and Nadia.

Now this round is called “The shoe’s on the other foot” because we ask you a question that the other team are experts on. They get to laugh when you get it wrong but don't worry the shoe will be on the other foot once we get to the second part and it’s their turn.

Peter and Nadia, a brainy neuroscience question for you. So Duncan, Lívia, no chipping in here.

Q: The human brain accounts for about 2% of your body weight. To the nearest 10%, how much energy does it use, as a percentage of the total energy used by the body?

Peter - So how much energy does the body use? The rest is probably 300 watts, 400 watts?

Nadia - I know that the brain requires a lot of glucose and oxygen. So when you are oxygen deprived, you can get brain damage.

Peter - So it’s to the nearest 10 percent?

Chris - I just need a number in percentage terms. I'll give you plus or minus 10 percent of how much of your total energy burn in a day your brain, which makes up two percent of your body weight, uses.

Peter - 30? 20? Not 50.

Nadia - 30 or slightly more?

Peter - Fourty?

[Incorrect buzzer sounds]

Chris - Unfortunately no, it's about 20 percent. About 20 percent of your cardiac output goes to your brain and your cardiac output, the amount of blood your heart pumps, is delivering oxygen and therefore that's a good index for how much of your metabolism a certain tissue accounts for. The brain is your most metabolically hungry organ so about 20 percent of the calories you burn in a day will go up there. If your brains the size of the one that Duncan has in front of him, the model, then maybe not.

But yes a good 400 to 500 calories a day in an adult. So no points for that. Okay.

If you get this one wrong, it's the tiebreaker. If you get this one right, you can clinch it. Duncan and Lívia.

This is tech-yes or tech-no. In other words does it exist or not. Peter, you have to keep quiet.

Q: Does this exist. A talking and listening toilet?

Duncan - I think that probably exists. If not then we should make one. It sounds like a great idea.

Lívia - I just came back from Japan, it sounds like a great idea. Yes.

Duncan - We’re going to say that that exists.

[Correct buzzer sounds]

[Duncan & Lívia Cheering]

Chris - This has been showcased at the Consumer Electronics Conference. Apparently you can converse with the toilet via a smart assistant while you're doing whatever comes naturally to you on the toilet.

Peter - My question is, what is listening to apart from your voice? Do I get a medical diagnosis?

Chris -  I tell you what, though… I've just come back from Western Australia where a lab there are working on a smart toilet. And the idea is that where we used to talk about Farm to Fork, where you look at the food cycle of what's it comes off the farm, it goes down your throat. Now we're talking about paddock to porcelain. They're going to build a smart toilet which will analyse what you dump into it.

And that puts a whole new spin, as I put it to them, of logging onto the Internet. This thing's going to be online and it's going to track exactly what you put down the loo and therefore it can inform your smart fridge in terms of how to manipulate your diet to improve your overall health.

So we have a winner. Give yourselves a round of applause. Duncan and Lívia, you are this week's naked scientist big brain of the Week award winners. Well done. Your score of two out of the three. And you are our losers this week, Peter and Nadia, but don't let that bother you!