Armchair Adventures: Cave of the Glowworms

Armchair Adventures Glowworm Cave

By Evelyn Kelly, PhD

I stepped gingerly into the small, rickety boat along with my daughter and six others. We have been at the village of Waitomo about two hours south of Auckland, New Zealand. We are now descending on an underground river into the dark bowels of the earth into the Cave of the Glowworms. I have no idea what to expect. Are we going to be able to grab fireflies? 

I remember summer nights in Tennessee when we chased fireflies or lightning bugs and put them in a jar. We watched them twinkle and shine and wondered how they did it. A popular 1950’s song had a lilting melody and words to match: “Shine, little glow worm, glimmer, glimmer.” 

Related: Armchair Adventures: Bolivian Salt Flats

As we descend into the dark depths, it is church-mouse quiet, except for the paddle shoosh-shooshing against the water. It is cold, very cold, and water is dripping from somewhere onto our heads. 

“Look up!” In blackness, a myriad of stars appeared before our eyes! It looks like those that shine and twinkle on the Milky Way. Tiny beings are showing off for us. They are letting their little blue-green lights shine, shine, shine from the limestone roof of the cave. 

We paddle on for an hour, “oohing” and “ahhing.” These little cave glowworms are not fireflies; they are insects called Arachnocampa luminous. They emit a glow to attract mates and to entice prey, which they capture with sticky threads that hang down from their bodies. The light is a chemical reaction takes place in cells called photocytes. The enzyme luciferase excites a pigment luciferin, producing light, like the process used by lighting bugs. 

Related: Armchair Adventures: Banff, Ice Fields, & a $20 Cup of Chili

Females use the pulsing bioluminescence to entice the attention of male glowworms to fly up and mate with them. The product of the mating is larvae stuck to the roof that also glow and attract mosquitoes and other insects in their sticky threads.  

As we emerge from the Cave of the Glowworms, we blink and warm up a little. What an experience! But is there a lesson from the twinkling lights of the cave? We saw small insects living a happy life as nature intended. Maybe, we can relate to a simple children’s song: This little light of mine, I’m going to let it shine…