What makes glowworms glow?

If you were to gaze upon a cave full of New Zealand glow worms, you may think you’re looking at a star-lit night sky. Using a small organ at the end of their bodies, these tiny gnat larvae illuminate surfaces of the caves and ravine walls they call home. In this segment, we meet biochemists on a mission to discover the molecular basis for the glow worm’s bioluminescence.

TRANSCRIPT

If you were to gaze upon a cave full of New Zealand glowworms, you may think you're looking at a star-lit night sky.

Using a small organ at the end of their bodies, this tiny gnat larvae illuminate surfaces of the caves and ravine walls they call home.

In this segment, we meet biochemists on a mission to discuss the molecular basis for the glowworm's bioluminescence.

Our partner 'Science Friday' has the story.

They're found right across New Zealand.

They like caves and they like the banks of steams and rivers.

They're carnivorous.

They use their light to attract their prey.

It's the larva of a kind of fungus net.

So, technically, a glowworm is actually a glowing maggot.

[ Laughs ] But that doesn't sound as romantic.

[ Laughs ] Doctors Kurt Krause and Miriam Sharpe are biochemists at the University of Otago.

Their goal is to shed some light on the New Zealand glowworm's particular method of illumination.

Before we started our work, no one knew exactly what makes the glowworm glow.

Possibly the best-studied, the most well-known of those systems is the firefly.

That system's really well-understood.

But, for some reason, no one had gone into that with the New Zealand glowworm.

And answered the basic question...

Are the glowworms going to have a unique mechanism of bioluminescence.

And, at first glance, you would say, 'Well, no, probably not, because glowworms and fireflies are sort of alike,' right?

But it turns out that fireflies are beetles, not flies, so they're quite different.

And because New Zealand has been isolated for more than 85 million years...

Creatures have had the opportunity to evolve systems, including bioluminescence, which are entirely independent from anywhere else.

Luckily for doctors Sharpe and Krause, they don't have to travel far to acquire specimens.

Nichols Creek -- it's just down the road, and that's where the New Zealand glowworm was initially described in a Royal Society publication, where this was like the big tourist attraction.

You walked up Nichols Creek and you saw the glowworms.

We go out at night.

They're very hard to find during the day.

What we do is -- we scan the area for a space with light coming out of it.

And I take a pointy stick -- A kebab stick works quite well.

You basically just touch the stick to the glowworm, and it comes off.

Oh, he's escaping.

Ah, got him.

And you put it into your tube and look for the next one.

Once they've got enough, they bring them back to their lab.

I lay them out on pieces of foil placed on dry ice and freeze them until I'm ready to use them.

When I want to carry out an experiment, I have to cut off their light organ on the end of their tail -- sac of those light organs -- and mush them up, then start doing a bit of biochemistry on them.

We separate out the proteins according to size.

And then test each protein for its ability to produce light.

We have a machine that can measure where the light is coming out of the samples.

Once they determine which molecules help to produce the light, they can get clues about the chemical processes at work.

There's chemical substrates...

Known as luciferin...

...that always reacts with oxygen.

But they won't react together very easily without a little bit of help.

A protein called an enzyme will hold the two molecules together in exactly the right way so that they will react together.

And it causes this small molecule to assume an excited state, where it then decays to a ground state and emits a photon.

So it's essentially like a little, tiny power plant, but on a molecular level.

Looking closer at the components of the glowworm substrate, its potential becomes brighter.

It's made out of chemicals which are different to the ones that the firefly uses.

And, so, their hypothesis is that the unique chemical components of the glowworm's glow could yield new tools.

People use bioluminescence as a tool all the time in biomedical research.

But the thing is -- with every different bioluminescence system, it has its own characteristics, and with different characteristics, you can come up with different uses for that particular system.

But that's not what keeps Dr. Krause and Dr. Sharpe interested in the glowworms.

If there are practical applications, that's great.

That's awesome.

But once you get into bioluminescence, you know, it kind of grabs you.

Whoa!

Animals making light.

How do they do that?