Twinkle Twinkle little star, how i wonder what you are....

When stepping into a cave that’s fully enclosed, cold, damp and you are not allowed to use torches or talk can be quiet discouraging of why you have been dragged into this in the first place (most likely by your weird adventurer or ecological friend…Cough). But once you get a chance to look around once you have stopped the toe stubbing walk down and your eyes have adjusted to the darkness; you see them.There are little stars everwhere. All over the roof, way up the banks and even all over the wall right next to you on the track. Just like little blue/green LEDs that take your breath away, who ever knew bugs could be so pretty? (=

The research paper i chose to discuss talks in an overall review of all of the aspects of the New Zealand species of Glowworm, Arachnocampa luminosa. As the method of prey capture interests me most as it is so unique and its main feature, I will talk in depth more about this and the general habitat and life cycles.

Glowworms are found to prefer the dark and damp habitats found commonly in caves, but they are able to survive on damp covered banks in dense forests areas. They are able to tolerate a wide range of temperature ranges and are only really affected by a change in relative humidity. It is estimated that the Glowworms and the mucus covered threads will dry out at a relative humidity of bellow 90-95%.

As the larvae stage is the longest lived stage of the Glowworm, lasting up to a year, it needs to gain a continuous sufficient amount of prey for its nutrients. The larva lives in a small transperant tube nest  that is suspendd from the roof of the cave and is roughly 2.5 times the length of its own body. New Zealand Glowworms are unlike most other species found overseas, the New Zealand/Australia species is strictly carnivorous feeding on mostly flying insects such as Diptra species and other aquatic insects.

There are considerable differences in the species consumed between the glowworms that live in the forest banks and in the caves, it also varies between summer and winter seasons. It catches its prey by producing numerous long silk “fishing line like” structures that dangle from its nest, covered in its own sticky mucus as glue. It creates these by using its mucus gland which is located in its mouth. The thread is made up of a continuous strand of droplets and the length is gauged not only by the age of the larvae, but the amount of air movement present. Extreme lengths of strands in quiet places can be from 1-50cm. The light that shins out the back end of the larvae through a chemical reaction produces an in vivo blue-green light that attracts insects which then get caught up in the lines. Insects naturally fly upwards towards a light source as it indicates an open space i.e. the night sky. Once caught, the movement of the live insect on the line triggers the Glowworm to move to the thread and retrieve its food. Both touch and chemoreceptors aid in the detection of its prey. As the prey moves more they are caught up in the line and the glow worm slims its way down the thread and pulls it up to feed on the insect. As it now has successfully caught it prey, it turns off its “light to save energy”.

 Once the larva has reached a length of 30-40mm in length it will crawl to find a free dark area to pupate, sometimes travailing up to several meters at a time. The trigger to move into the next stage of life from a larva to become a breeding adult is its body weight and/or size, not being influenced by a change in season or environmental condition.

 Once an adult, they have degenerate mouth parts and do not feed but instead only live for a couple days. In this time they have to find a mate and reproduce if they want to insure their genes are passed onto the next generation. As the adults are very poor fliers, they sometimes by misfortune get caught up in the larva fishing lines, thus getting then eaten by the other larva becoming cannibals.

 

The Male (left) and female (right) New Zealand A. luminosa adults.

 The eye sight of the larvae and the adults are functional on a green UV base line and have very large eyes.

An interesting fact is that Glowworms are found to be more tolerant of high CO2 emissions. With this in mind, and there ability to not be controlled by seasons, they would not have an inital effect on the current climate change issues.

And if you would like to check out the report yourself, here's the direct link:

http://onlinelibrary.wiley.com.ezproxy.lincoln.ac.nz/doi/10.1002/bio.955/pdf

Cheers for reading!!!!!!!!!

I hope you enjoyed my blog!!!

(=