Let's imagine for a moment there was such a thing as the underwater animal Olympics.

Which creatures of the deep do you think would dominate the metal leaderboards?

If we're talking about the competition for speed, you'd of course go with one of the world's

best known fast fish for gold.

How about a Marlin that can cut through water at speeds of up to 100 kilometers an hour?

Or maybe it's cousin, the swordfish?

Or perhaps even the super fast Mako shark?

But when it comes to the metal for swimming efficiency, would you still pick the same contenders?

Well, if you did, you'd probably come plumb last in the race, because although these fish

are super speedy, they're not exactly the best at using their power efficiently.

To find out who would take the top spot, we need to turn our attention to another rather

unlikely animal.

Poised on the starting blocks in the Olympic gold medal race for swimming efficiency, the

top contender is the soft and rather formless body of a jellyfish.

In this case, I'm talking specifically about the round translucent blob that is the moon

jellyfish, because for its mass, this jellyfish spends less energy travelling than any other

swimming animal, or in fact any animal at all.

So how does this unassuming lump of jelly win gold?

Well the answer comes down to how the moon jellyfish moves.

It's a technique that's so clever and so energy efficient, it's being copied by scientists

to develop a new type of underwater robot.

Did you know that jellyfish are amongst the oldest and simplest organisms that live in

...