Look up.

What do you see?

Orion?

The Seven Sisters?

The Milky Way?

Look again.

You're not outside.

And these aren't stars...They're alive.

These are glow worms.

The spectacular larvae of a rather un-spectacular gnat, called Arachnocampa luminosa.

Deep inside the Waitomo caves on New Zealand's North Island, these bioluminescent worms hang from the ceiling in hammocks of their own silk.

Their huge colonies turn these dark recesses into a natural planetarium.

You've heard of mimicry in nature?

This is more like astro-mimicry.

Fireflies generate light the same way-with chemicals-to find mates.

But these worms use their light to hunt.

See the delicate threads hanging around each worm?

The light is the bait.

These threads are the snares.

The worm drops them, bit by bit like a string of mardi gras beads.

Together, they form glittering chandeliers.

For moths, fluttering through the dark cave, it's dazzling.

Moths aren't drawn to light, like you might think.

Rather, they navigate by it.

They use the moon and stars like a compass, to fly in a straight line.

But with imposter stars all around, they become disoriented...and fly into the light.

That's when the worm springs its trap.

Caught in the slimy threads, the moth quickly becomes exhausted.

And the worm reels in its catch.

Even a daytime flyer, like this mayfly, can get lost in the cave.

It struggles to escape, but only coats itself in more goo.

Slime seeps into its breathing holes.

And it's still alive when the worm begins to feed.

Scientists have noticed that these glow worm colonies brighten and dim on 24 hour cycles.

In other words... they have a circadian rhythm.

Which is... odd, for a worm that lives its whole life half a mile deep in a cave.

It's never experienced day and night.

What's more...each colony in the cave follows its own rhythm.

They're offset... almost like they're taking turns feeding on the moths.

The result: the endless starry night inside the Waitomo Caves... A bright, glittering mantle cloaking a much darker purpose.

Hi it's Amy.

If you like stuff that glows, go toward the light... We have some other stories you might like - - like this one, about the incredible ways that squid make themselves invisible, or the surreal nano-powered blue of the morpho butterfly.

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