#41 - Steamship and Glow Worms

There’s a lot to do around Queenstown.  So after our helicopter ride (the highlight of this area for us), we took a little cruise on Lake Wakatipu over to Walter Peak on a 106 year old coal fired steamship.  It was launched in the same year as the Titanic in 1912.  Fortunately, there are no icebergs on this lake. 

Jeff descended into the boiler room and watched them shovel coal.  The stoker was very busy, as the ship burns one ton of coal every hour!  I’m thinking this guy needs a good long shower when he gets home at night.  

The next day we ventured down to Te Anau where we went to the Glow Worm caves.

As I kid, I remember the song, “Glow little glow worm, glimmer, glimmer”.  We used to catch fireflies in jars in the summer and were mesmerized by the on again, off again, blinking lights they emitted.  So when I had an opportunity to see the glow worms in their natural habitat, I thought, let’s find out what makes them glow.

The glow worms in NZ are found only in caves and they are not like the ones I captured in a jar.  And tourists flock by the thousands to see them. They like dark, very damp places (the glow worms, not the tourists).  Unless they are happy they won’t glow.  They attach themselves to horizontal places like ceilings of the caves and their bluish-white lights give the appearance of twinkling stars in a night sky.  It’s really quite a beautiful site as you travel through the cave on a small boat, gazing at thousands of these little twinkling lights.  

So here’s what’s really going on.  

The lifecycle of a Glowworm is in 4 stages and takes about 11 months.  Eggs are laid in clutches of 30-40 on walls and ceilings.  Immediately upon hatching from the egg, the larvae (aka maggots) emit a light, build a nest, put down lines, and feed.  About the length of a matchstick, they put out strings of a sticky substance that traps insects on which they feed.  

Starting to sound a little less glamorous, huh?  Keep reading.  

The glow is the result of bioluminescence, which is a reaction between the chemicals given off by the glowworm and oxygen in the air.  This reaction produces light.  Insects fly towards the light and get stuck in the sticky lines they’ve put out.  

So how are these lines created?  The larva construct a tube of mucus up to a foot long.  Then it coughs up dozens of silk strings, about a sixth the width of a human hair, and up to nearly two feet long, and dangles them from the bottom of the tube.  It regurgitates mucus onto the silk, which collect in tiny droplets.  

Insects fly toward the beckoning light and get stuck in this glue-like mucus.  The glow worm pulls up the strings, eating them and pulling them up until it comes to the prey.  Dinner is served.  

Typically the glow worm gets along well with its thousands of neighbors, but if it feels attacked it will kill and eat a threatening fellow glow worm.  

Once a glow worm larva becomes an adult, things look pretty grim.  The glow has worn off, so to speak.  The adult, which looks like a large mosquito, has no digestive system so it can’t eat.  They have no mouth and their only function is to reproduce.  Usually a male is waiting for the female to emerge from the pupa and mating takes place immediately.  The female only lives a few days. Okay, so we’re looking at wild sex for a couple days, but starvation and then death.  Glad I wasn’t born a glowworm.  

We had a great guide who took us through the caves.  At the end, he said lots of people come for this tour because they read about how enchanting the glow worms are.  

He asked, “How many of you would have paid to come to see this if we told you you’d be seeing bunch of maggots who cough up mucus, eat their own poop, and cannibalize their neighboring glow worms?”

Point well taken.  

As a bonus on this trip, we also experienced the beauty of the caves themselves.  This underground world is astonishingly beautiful.  By geological standards the caves are very young, only 12,000 years old.  A foreceful river flows through them carving out passages filled with limestone rocks, whirlpools and a roaring underground waterfall.  The glow worms don’t like all this noise.  So they hide out in a silent hidden grotto which is accessible only by boat.

P.S.  In case you were wondering, it has been established that the glow worm does not make a good pet.

Photography is not allowed in the caves as any light makes the glow worms shut down their glowers.  I got these photos off the internet just to give you an idea of what it looks like. 

     This is pretty much what it looked like except the lights were more blue than green.                                                          

Below are sticky strings that capture “food” 

The adult glowworm looks like a large mosquito. They have no mouth and their only function

Sticky strings that capture “food”