Biology

The incredible cave with lights of unexpected origin

In Waitomo, New Zealand, there is an incredible place. A limestone cave full of bright lights with an unexpected origin: glowing worms thanks to the phosphorescence that gives it a very special appearance.

The worm responsible for this luminous appearance is Arachnocampa luminosa , the larva of a fly known as titiwai among the Maori (which projects on the water) or fungus gnat in Spanish.

This cave has been wonderfully photographed by Shaun Jeffers in these wonderful photographs. (At the end of the article we explain much more about this amazing worm).

The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave
The incredible cave

It was first observed in New Zealand, in a gold mine in the Thames region, giving it the name  Bolitiphila luminosa . At present, the name of the species is the one we have named before.

Arachnocampa luminosa life cycle

The larvae of this mosquito are carnivorous and use bioluminescence to attract prey to their nests. The eggs are deposited directly on the walls of the cave. When the larva hatches, it immediately begins to glow. The larva is cylindrical and usually measures between 3 and 5 millimeters long when they hatch. During its larval stage it will reach between 3 and 4 centimeters in several months.

The incredible cave
The incredible cave

The larvae can move around the surface of the cave before finding the ideal area to build their silk cocoon. Most of the larvae emerge during the spring.

The larva makes a silk nest on the ceiling of the cave and leaves 30 threads of silk that contain small sticky droplets . Their prey, which normally include other diptera such as mosquitoes but also when they live in groups, can trap spiders and other flightless invertebrates. When the prey is trapped, the larvae ingest it alive.

After five larval stages, the larva will be suspended on a long thread and will remain for 24 hours. The pupal phase lasts approximately two weeks. During this time, the pupa continues to glow, although the males eventually lose their shine.

The adults that eventually emerge are bad fliers and generally do so during the winter. They usually live up to 76 hours in the case of females and up to 96 hours in the case of males. Females generally lay more than 100 eggs and the eggs hatch after about 20 days. 

Sources of glowworm mortality include predation by opilions (including short-legged opilions, Hendea myersi cavernicola and long-legged, Megalopsalis tumida ), parasitic fungi ( Tolypocladium sp.), And possibly cannibalism when adults entangle in other larval silk threads.

Bioluminescence that gives beauty to the caves

The larvae of this species glow to attract prey to their silk threads . The shine is produced thanks to the Lucifer enzyme that acts on a small molecule of Luciferin, as it happens in other species. The luciferin of this species has similarities to that of fireflies, but the enzyme is quite different.

Luminescence occurs in the excretory organs known as Malpighi’s tubes in the abdomen.  

Both the pupa and the adult also have bioluminescence although its purpose is not very clear, it could be to attract a mate but it could also be that it simply occurs because the metamorphosis does not alter the Malpighi tubes.

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