Bioluminescence: The World of Gollum and Glow-Worms

Ever since discovering glow-worms one night while out for a walk at a New Zealand campsite and then seeing them highlighted in our Creatures of Light exhibition, I’ve wanted to visit the Waitomo Caves. This is where glow-worms live in abundance, hanging their sticky feeding lines above the cave’s river and catching insects that emerge from the river, attracted to the glow-worms’ self-produced light.

"Curtains" of silver strands hang from a cave ceiling.

The New Zealand glow-worm, Arachnocampa luminosa, spends most of its life in the larval stage, eating insects entangled in its gluey strings or other glow-worms if they get too close. The adult looks like a mosquito, has no mouth, and lives for only a few days—long enough to mate, disperse and lay eggs. Image: Courtesy of Waitomo Glowworm Caves

The Māori name for the Waitomo caves derives from wai, meaning “water”, and tomo, meaning “entrance” or “hole”. The caves were discovered in 1887 by local Māori Chief Tane Tinorau and English surveyor Fred Mace, when they floated along the river and into the cave on a flax raft, using candles for light.

A waterway leads into a cave.

Explorers adventured down this channel and discovered the hidden world of the glow-worms. Image: Courtesy of Waitomo Glowworm Caves

The cave ceiling is covered with small dots of silver blue light emitted by the glow-worms. Beautiful but deadly (for their prey) threads are suspended below the worms and look like beaded necklaces.

A boatload of visitors in the cave.

Glow-worms produce their own light to attract unsuspecting prey, making the ceiling look like it is covered in fairy lights. Image: Courtesy of Waitomo Glowworm Caves

The atmosphere in the cave is surreal because of the thousands of soft lights above and the cave seeps dripping in irregular plops into the river. Movie director Peter Jackson recorded the cave’s sounds to give that same eeriness to Gollum’s cave in The Hobbit.

An irregular cave ceiling with glow-worm threads hanging down.

Dark and mysterious, the caves inspired the refuge of the monstrous Gollum. Image: Courtesy of Waitomo Glowworm Caves

Visiting the cave after attending a conference in Auckland, I learned that more than glow-worms are there. Chief Tane Tinorau had also discovered an upper level, full of chambers and catacombs decorated with cascades of gold stalactites. “The Cathedral” chamber has such good acoustics that it is used for underground concerts.

Interior of The Cathedral.

“The Cathedral” is a dry cave above the glow-worm grotto. It got its limestone coat 30 million years ago when it was under water. Geological and volcanic activity uplifted the cave network. Rainwater seeps through the cracks to cause stalactites to form. A stalactite grows 1 cubic centimetre every 100 years, on average. Image: Courtesy of Waitomo Glowworm Caves

In 1990, the New Zealand government returned the caves and the surrounding lands to Tane Tinorau’s descendants, many of whom now lead the tours.

A view down a shaft in the rock.

A 16 metre-deep limestone shaft carved by a waterfall, showing layers of limestone formed from an ancient seabed. Image: Courtesy of Waitomo Glowworm Caves

When you visit the Creatures of Light exhibition at the museum, immerse yourself in its replica glow-worm grotto and imagine yourself drifting slowly below with the only sound being the slow drip of cave water. Could that be Gollum who is peering at you from the end of the tunnel?

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6 Responses to Bioluminescence: The World of Gollum and Glow-Worms

  1. Peggy Leger says:

    great article! Are there glow worms around Ottawa?

    • Robert Anderson says:

      Thanks for your question Peggy.
      The glow-worms referred to in New Zealand are fly larvae and unfortunately are found only in New Zealand and Australia. In Ontario the closest things we have to the glow-worms are fireflies of the beetle family Lampyridae. Most larval forms of fireflies are unknown, but all are thought to be bioluminescent. Among adult fireflies, bioluminescence occurs in some genera but not in others. Each bioluminescent species has a unique flash pattern that allows for species-specific recognition.

      A good reference is The Fireflies of Ontario at

  2. Wendy Hampson says:

    Thank you Kathleen for a truly informative visit to the Glowworm caves. By your description I feel as though I have now been there myself. I loved how you wrote the blog incorporating such interesting factoids as Peter Jackson and Gollum that allowed me to relate more to a fascinating place in a faraway land. Your last line gave me the shivers to think that Gollum might be watching!

    • Kathleen Conlan says:

      Wendy, thanks for your kind words. Glad you enjoyed my article!
      The thought of seeing Gollum at the end of the tunnel would give anyone the shivers 🙂

  3. Claudette David says:

    Fascinating! Kathy, many thanks for including me in the distribution.

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