Arachnocampa
2881462
225582686
2008-07-14T12:26:13Z
Mark-mitchell-aldershot
3401544
{{Taxobox
| name = ''Arachnocampa''
| image = Arachnocampa luminosa larvae.jpg
| image_caption = ''Arachnocampa luminosa'' larvae
| regnum = [[Animal]]ia
| phylum = [[Arthropod]]a
| subphylum = [[Hexapoda]]
| classis = [[Insect]]a
| subclassis = [[Pterygota]]
| infraclassis = [[Neoptera]]
| superordo = [[Endopterygota]]|
| ordo = [[Fly|Diptera]]
| subordo = [[Nematocera]]
| infraordo = [[Bibionomorpha]]
| familia = [[Mycetophilidae]]
| genus = '''''Arachnocampa'''''
| subdivision_ranks = Species
| subdivision = <center>Various - see text<center/>
}}
'''''Arachnocampa''''' is a genus of four [[fungus gnat]] species which are, in their [[larval]] stage, [[glowworm]]s. They are found in [[New Zealand]] and [[Australia]] in caves and grottos, or sheltered places in forests.
The genus was called '''''Bolitiphila''''', meaning [[mushroom]] lover, in the past. The name was changed in [[1924]] to ''Arachnocampa'', meaning [[spider]]-grub, for the way the [[larva]]e hang silk threads to trap prey. The genus ''Arachnocampa'' belongs in the family [[Mycetophilidae]].
== Common features ==
''Arachnocampa'' species go through a life cycle of eggs hatching to [[larva]]e then pupating to an adult fly. They spend most of their life as larvae.
The larval stage lasts about 6 to 12 months, depending on food. The larva emerges from the egg only about 3 to 5 millimetres long, and through its life grows to about 3 centimeters.
The larva spins a nest out of silk on the ceiling of the cave and then hangs down as many as 70 threads of silk (called snares) from around the nest, each up to 30 or 40 cm long and holding droplets of mucus. The larvae can only live in a place out of the wind, to stop their lines being tangled, hence caves, overhangs or deep rainforest.
The larva glows to attract prey into its threads, perhaps luring them into believing they are outdoors, for the roof of a cave covered with larva can look remarkably like a starry sky at night. A hungry larva glows brighter than one which has just eaten.<ref>[http://springbrook.info/glow_worms/index.htm Springbrook Glow Worms Research Centre]</ref> Prey include [[midge (insect)|midge]]s, [[mayflies]], [[caddis flies]], [[mosquito]]s, [[moth]]s, or even small [[snail]]s or [[millipede]]s. When prey is caught by a line the larva pulls it up (at up to about 2 millimetres a second) and feeds. If prey is scarce the larvae will turn to [[cannibalism]], eating other larvae, pupae or adult flies.
The glow is the result of a chemical reaction that involves [[luciferin]], a waste product; [[luciferase]], the enzyme that acts upon luciferin; [[adenosine triphosphate]], the energy molecule; and [[oxygen]]. It occurs in modified excretory organs known as [[Malpighian tubules]] in the abdomen.<ref name="Green">'''Green''', L.B.S. (1979) The fine structure of the light organ of the New Zealand glow-worm Arachnocampa luminosa (Diptera: Mycetophilidae). ''Tissue and Cell'' '''11''': 457-465. </ref>
The body of the larva is soft while the head capsule is hard. When it outgrows the head capsule it [[ecdysis|moults]], shedding its skin. This happens four times through its life.
At the end of the larva stage it becomes a [[pupa]], hanging down from the roof of the cave. The pupa stage lasts about 1 or 2 weeks and it glows intermittently. The male stops glowing a few days before emerging, the female's glow increases. The glow from the female is believed to be to attract a mate, and males may be waiting there when she emerges.
The adults (of both sexes) cannot feed and live only a short time. They glow, but only intermittently. Their sole purpose is to mate, and for the female to lay eggs. Adult insects are poor fliers and so will often remain in the same area, building a colony of glowworms. The female lays a total of about 130 eggs, in clumps of 40 or 50, and dies soon after laying. The eggs hatch after about 20 days and the cycle repeats.
The larvae are sensitive to light and disturbance and will retreat into their nests and stop glowing if they or their snares are touched. Generally they have few predators. Their greatest danger is from human interference.
==Species==
* '''''Arachnocampa luminosa''''' is found in [[New Zealand]], on both the [[North Island|North]] and [[South Island|South]] islands. Its [[Māori]] name is '''titiwai''', meaning "projected over water". The [[Waitomo Caves]] on the North Island near [[Pirongia]] is one well-known habitat. It was first known to science in [[1871]] when collected from a [[gold mine]] in the [[Thames, New Zealand|Thames]] region. At first it was thought to be related to the European glowworm beetle, but in [[1886]] a [[Christchurch]] teacher showed it was a larva of a [[gnat]], not a beetle. The species was called ''Bolitiphila luminosa'' in [[1891]], before being renamed ''Arachnocampa'' in [[1924]]. The [[harvestman]] spider preys on the luminosa eggs, larvae and pupae, and even the adult flies. Small orange harvestman spiders live in the same caves as the luminosa; larger spiders will come into the caves for food and shelter. A [[fungus]] also affects the luminosa; it gradually kills the larva. Fungus [[spore]]s are spread by air movement, but since the larvae live out of the wind the spread of spores is limited. ''Arachnocampa luminosa'' is found only in New Zealand. In the United States, the bioluminescent fly larva found at [[Dismals Canyon]] is a distant relative, called ''Orfelia fultoni''. It doesn't make the hanging silk lines of ''Arachnocampa'' and produces light from a different part of its body.
* '''''Arachnocampa richardsae''''' is found in [[New South Wales]]. The [[Newnes Glow Worm Tunnel]] in the [[Blue Mountains (Australia)|Blue Mountains]] is one well-known habitat.
* '''''Arachnocampa tasmaniensis''''' is found in [[Tasmania]] (as the name suggests). One habitat is the [[Marakoopa Cave]], [[Mole Creek, Tasmania|Mole Creek]] near [[Cradle Mountain]].
* '''''Arachnocampa flava''''' is found in [[Queensland]]. The [[Natural Bridge, Queensland|Natural Bridge]] in the [[Gold Coast, Queensland|Gold Coast]] hinterland is one well-known habitat.
* '''''Arachnocampa Sp.Mt Buffalo'''''. A colony of ''Arachnocampa'' has been found in an alpine cave on [[Mt Buffalo]] in [[Victoria (Australia)|Victoria]]. Early research suggests it is a new species, but related to the ''tasmaniensis'' and the New Zealand ''luminosa''. Its presence suggests [[rainforest]] may have extended up the mountain in the past.<ref>
[http://www.abc.net.au/science/slab/glowworm/default.htm ''The Lure of Glow Worms''], science feature at the [[Australian Broadcasting Commission]]</ref> The [[Government of Victoria|Victorian Government]] presently has it listed (called the Mt Buffalo Glow-Worm) as a threatened species.<ref>[http://www.dse.vic.gov.au/CA256F310024B628/0/ECBE4FF8F1BE1B5BCA2571460020CC9A/$File/FFG+threatened+list+april+2006.pdf Threatened List April 2006], at the Victorian Department of Sustainability and Environment</ref>
* '''''Orfelia fultoni''''' can be found in the [[Appalachia]] area of the United States. A [[National Natural Landmark]], named "[[Dismals Canyon]]", is home to this variety of larva.
The larvae of Keroplatidae also evidence blue luminescence and is found in almost all european countries, from Portugal in the southwest to Scandinavia in the Northeast.
== References ==
<references/>
* ''The New Zealand Glowworm'' by V.B. Meyer-Rochow, 1990, Published by Waitomo Caves Museum Society. 60 pages (ISBN 0-908683-09) [The book can be obtained from: Waitomo Caves Museum, P.O.Box 12, WAITOMO CAVES, NEW ZEALAND]
* ''The Glow-Worm'', Ormiston Walker and Judy Kerdel, MacMillan New Zealand, 1990, ISBN 0-7329-0121-9. (A children's book.)
* ''Glowworm'' article, [[Encyclopædia Britannica]], 15th edition
== External links ==
* [http://soilbugs.massey.ac.nz/insecta.php Soil Bugs - An illustrated guide to the New Zealand invertebrates]
* [http://www.waitomocaves.co.nz/glowworm-caves-boat-ride/361/Glowworm+Lifecycle.aspx The Glowworm Lifecycle]
* [http://www.teara.govt.nz/1966/G/Glow-worm/Glow-worm/en Glowworm article in the ''Encyclopaedia of New Zealand 1966'']
* [http://www.geocities.com/orchidsnz/wbgglow.htm Glowworms page]
* [http://www.uq.edu.au/~uqdmerri/Pages/GWglow-worm%20home.html Australian glow-worms]
[[Category:Flies]]
[[Category:Insects of New Zealand]]
[[Category:Insects of Australia]]
[[Category:Bioluminescent organisms]]
[[Category:Cave biology]]
[[simple:Arachnocampa]]