Te Anau Glowworm Caves

The glowworm cave we visited is located on the ewestern shores of Lake Te Anau. The cave itself is part of a 6.7km, four-level limestone labyrinth known as the Aurora Caves system. The caves are about 12,000 years old, which is quite young in geological terms, but the limestone they carve through is ancient - up to 35 million years old.
Unlike many dry cave systems, the Te Anau glowworm caves are still increasing in size. The "Tunnel Burn" river that flows through the caves is mildly acidic, which helps the water dissolve the rock and create passages. This acidity is produced from carbon dioxide which originates from the forest floor high above the caves. Because the Te Anau glowworm caves are young and still have a river running through them, stalactittes and stalagmites are only just starting to form. Speleothems are more common in what seemed to be the older, and drier, upper passages of the caves.
The entrance to the cave was quite low, having to basically duck walk in order to get through, but this quickly opened up into a secton known as the Cathedral. This section is roughly 20m high - the highest known point in the Aurora Caves. At the far end of the Cathedral, close to a waterfall, there are fossilized shell fragments that were noticeable in the limestone walls. These would have to date back to when the limestone formed under the sea millions of years ago... a breathtaking site.
Past the waterfall, a whirlpool and natural sandstone bridge are good examples of how the water wears and cuts is way through the limestone. At the end of the walkway, we boarded a small boat and drifted into a section known as glowworm grotto, which seemed to be a small lake-like section of water accumulation (it was pitch black in order to see the glowworms so it is hard to tell for sure.)
Adult Fly (1-5 days) - The adult fungus gnat's only purpose is to breed and disperse. The female usually dies immediately after laying eggs. The males live up to five days. They are born without functioning mouthparts.
Eggs (20-24 days) - Each adult lays approximately 130 tiny sticky eggs. They hatch about three weeks later. Hatching occurs in all seasons but is most common in December.
Larva (9 months) - As soon as it hatches, the glowing larva builds a nest and begins catching food. Once it reaches 30-40mm, it covers itself in a protective skin, much like a cacoon, and becomes a pupa.
Pupa (12-13 days) - Suspended on a long thread, the larva begins turning into an adult fly. Both males and females emit light but the female becomes much brighter before she hatches, attracting adult males.
Glowworms "fish" for food by dangleing as many as 70 "fishing lines" which are 20-150mm long and covered with thick sticky droplets of mucus. The glowworm's light attracts insects which then become trapped and paralysed by chemicals in the lines. When the glowworm feels vibrations on a line, it quickly hauls in its victim, kills it, and feeds. The glowworm's light is produced as a by-product of excretion. A reaction takes place in small tubes near the tail between an enzyme called cuviferase and other chemicals, producing a blue-green light.
The glowworm's main predator in the caves is the harvestman, similar to a spider. If food is scarce, and glowworms live too closely together, they have been known to cannibalize eachother. Glowwroms need high humidity, close to saturation point, or else they dry out and die. Many other creatures live in the cave system including weta, earthworms, spiders, millipedes, beetles, isopods, amphipods, as well as the aforementioned harvestman. The water supports native long-finned eel, which can grow up to 1.7m long and weigh up to 25 kg, as well as small native fiash called kaoro. Some creatures, such as cave beetles and harvestmen, live their entire lives in the caves and cannot survive outside. After living in the dark so long, many have lost pigmentation and developed highly sensitive sensory organs to detect prey. Others, such as glowworms, can survive equally well oustide caves, as long as they may find cool, dark habitats reminiscent of the cave environment.