Arachnocampa

Arachnocampa

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Arachnocampa is a genus of four fungus gnat
Fungus gnat
Fungus gnats are small, dark, short-lived flies, of the families Sciaridae, Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae and Mycetophilidae , sometimes placed in the superfamily Mycetophiloidea, whose larvae feed on plant roots or fungi and aid in the decomposition of organic matter...

 species which are, in their larval stage, glowworm
Glowworm
Glowworm, or glow worm, is the common name for various groups of insect larvae and adult larviform females that glow through bioluminescence. They may sometimes resemble worms, but all are insects .-Classification:Major families are:* Lampyridae , found around the world...

s. They are found mostly in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 in caves and grottos, or sheltered places in forests.

The genus was called Bolitiphila, meaning mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

 lover, in the past. The name was changed in 1924 to Arachnocampa, meaning spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

-grub, for the way the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e hang silk threads to trap prey. The genus Arachnocampa belongs in the family Keroplatidae.

Common features


Arachnocampa species go through a life cycle of eggs hatching to larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

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. In some species, the droplets of mucus on the silk threads are poisonous enhancing the trap's ability to subdue prey quickly.

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. Prey include midge
Midge (insect)
Midges comprise many kinds of very small two-winged flies found world-wide. The term does not encapsulate a well-defined taxonomic group, but includes animals in several families of Nematoceran Diptera. While some midges are vectors for disease, many others play useful roles as prey items for...

s, mayflies, caddis flies, mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

s, moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

s, or even small snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s or millipede
Millipede
Millipedes are arthropods that have two pairs of legs per segment . Each segment that has two pairs of legs is a result of two single segments fused together as one...

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
Cannibalism (zoology)
In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species...

, eating other larvae, pupae or adult flies.

The glow is the result of a chemical reaction that involves luciferin
Luciferin
Luciferins are a class of light-emitting biological pigments found in organisms that cause bioluminescence...

, a waste product; luciferase
Luciferase
Luciferase is a generic term for the class of oxidative enzymes used in bioluminescence and is distinct from a photoprotein. One famous example is the firefly luciferase from the firefly Photinus pyralis. "Firefly luciferase" as a laboratory reagent usually refers to P...

, the enzyme that acts upon luciferin; adenosine triphosphate
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

, the energy molecule; and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

. It occurs in modified excretory organs known as Malpighian tubules in the abdomen.

The body of the larva is soft while the head capsule is hard. When it outgrows the head capsule it moults
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

, shedding its skin. This happens four times through its life.

At the end of the larva stage it becomes a pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

, 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
    New Zealand
    New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

    , on both the North
    North Island
    The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

     and South
    South Island
    The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

     islands. Its Māori
    Maori language
    Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...

     name is titiwai, meaning "projected over water". The Waitomo Caves
    Waitomo Caves
    The Waitomo Caves are a village and cave system forming a major tourist attraction in the southern Waikato region of the North Island of New Zealand, 12 kilometres northwest of Te Kuiti. The community of Waitomo Caves itself is very small, though the village has many temporary service workers...

     on the North Island near Pirongia
    Pirongia
    Pirongia is a small town in the Waipa District of the Waikato region of New Zealand's North Island.It is 12 kilometres to the west of Te Awamutu, on the banks of the Waipa River, close to the foot of the 962 metre Mount Pirongia, which lies in a forest park to the west of the town.Pirongia was...

     is one well-known habitat, the caves having become a popular tourist attraction. It was first known to science in 1871 when collected from a gold mine in the Thames
    Thames, New Zealand
    Thames is a town at the southwestern end of the Coromandel Peninsula in New Zealand's North Island. It is located on the Firth of Thames close to the mouth of the Waihou River. The town is the seat of the Thames-Coromandel District Council....

     region. At first it was thought to be related to the European glowworm beetle, but in 1886 a Christchurch
    Christchurch
    Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...

     teacher showed it was a larva of a gnat
    Gnat
    A gnat is any of many species of tiny flying insects in the Dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae.In British English the term applies particularly to Nematocerans of the family Culicidae...

    , not a beetle. The species was called Bolitiphila luminosa in 1891, before being renamed Arachnocampa in 1924. A species of harvestman preys on the luminosa eggs, larvae and pupae, and even the adult flies. A fungus
    Fungus
    A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

     also affects A. luminosa; it gradually kills the larva. Fungus spore
    Spore
    In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

    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.

  • Arachnocampa richardsae is found in New South Wales
    New South Wales
    New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

    . The Newnes glow worm tunnel
    Newnes Glow Worm Tunnel
    The Newnes glow worm tunnel is a disused railway tunnel in the Wolgan Valley, New South Wales, Australia, that is famous for its resident glow worms, the bioluminescent larvae of Arachnocampa richardsae, a type of fungus gnat.-Description and history:...

     in the Blue Mountains is one well-known habitat.

  • Arachnocampa tasmaniensis is found in Tasmania
    Tasmania
    Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

     (as the name suggests). One habitat is the Marakoopa Cave, Mole Creek
    Mole Creek, Tasmania
    Mole Creek is a town in the upper Mersey Valley, in the central north of Tasmania, Australia. At the 2006 census, Mole Creek had a population of 223. The town primary school also services the surrounding districts including Chudleigh and Caveside. The nearest high school and regional centre is...

     near Cradle Mountain
    Cradle Mountain
    Cradle Mountain is a mountain in the Cradle Mountain-Lake St Clair National Park, Tasmania, Australia. Rising to 1,545 metres above sea level it is one of the principal tourist sites in Tasmania, owing to its natural beauty...

    .

  • Arachnocampa flava is found in Queensland
    Queensland
    Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

    . The Natural Bridge in the Gold Coast
    Gold Coast, Queensland
    Gold Coast is a coastal city of Australia located in South East Queensland, 94km south of the state capital Brisbane. With a population approximately 540,000 in 2010, it is the second most populous city in the state, the sixth most populous city in the country, and also the most populous...

     hinterland is one well-known habitat.

  • Arachnocampa Sp.Mount Buffalo. A colony of Arachnocampa has been found in an alpine cave on Mount Buffalo in Victoria
    Victoria (Australia)
    Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

    . Early research suggests it is a new species, but related to the tasmaniensis and the New Zealand luminosa. Its presence suggests rainforest
    Rainforest
    Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...

     may have extended up the mountain in the past. The Victorian Government
    Government of Victoria
    The Government of Victoria, under the Constitution of Australia, ceded certain legislative and judicial powers to the Commonwealth, but retained complete independence in all other areas...

    presently has it listed (called the Mount Buffalo Glow-Worm) as a threatened species.

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