Weta
From Wikipedia, the free encyclopedia
- This article is about the insect. For other uses, see Weta (disambiguation).
| iWeta | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Poor Knights giant weta (Deinacrida fallai) - this specimen has an overall length of 20cm (8")
|
||||||||||||||||||||
| Scientific classification | ||||||||||||||||||||
|
The weta family comprises around 70 insect species endemic to the New Zealand archipelago. They are large by insect standards, some species among the largest and heaviest in the world. Their physical appearance is that of a cross between a cockroach and a cricket with the addition of large legs. Their name (strictly, wētā) comes from the Māori language, but has been incorporated into New Zealand English, so the plural "wetas" may appear.
Contents |
[edit] General characteristics
By virtue of their ability to cope with variations in temperature, weta can be found in a variety of environments including alpine, forests, grasslands, caves, shrub lands and urban gardens. They are nocturnal and flightless, with a diet consisting of leaves, other insects, fungi, dead animals and fruit.
Weta are capable of biting. In fact, tree weta bites are particularly common. They can also inflict painful scratches with the potential of infection. Weta are known to arc their hind legs into the air in warning to foes.
New Zealand had no native land mammals apart from native bats prior to the arrival of humans. Ecological niches that were filled by mammals in other parts of the world were filled by native fauna in New Zealand. The weta’s place in the ecosystem is comparable to that held by mice and other rodents elsewhere in the world. For example, like their foreign mouse equivalents, they are hunted by an owl: in this case the Morepork, New Zealand’s only surviving native owl. Weta also pass seeds of some plant species through their digestive tracts unharmed, thus acting as seed dispersers. It is yet to be seen how decreases in weta populations are affecting native plant species that rely on the weta's help.
[edit] Taxonomy and evolution
Weta have survived virtually unchanged since the Mesozoic era, possibly because they had few native predators. In this respect, they can be compared with the tuatara. Fossilized weta have been found in Australia, although they do not exist there now. This proves they were present in ancient Gondwanaland, prior to the separation of New Zealand from that ancient landmass.
Giant, tree, ground and tusked weta are all members of the family Anostostomatidae (traditionally in the Stenopelmatidae, but recently separated). Cave weta are members of the family Rhaphidophoridae, in a different Ensiferan superfamily.
[edit] Giant weta
There are 12 species of giant weta (Deinacrida spp.), most of which are significantly larger than other weta, despite already being large by insect standards. They are heavy insects with a body length of up to 10 centimetres (3 in) not inclusive of its lengthy legs and antennae, and weigh more than 70 grams (2.5 oz), making it the heaviest documented insect in the world[1] and heavier than a sparrow. The largest species of giant weta is the Little Barrier Island weta also known as the wetapunga (god of ugly things). Giant weta tend to be less social and more passive than other weta. They are classified in the genus Deinacrida, which is Greek for terrible grasshopper. They are found primarily on small islands off the coast of the main islands.
[edit] Tree weta
Tree weta (Hemideina) are those most commonly encountered in suburban settings. They are up to 40 mm long and most commonly live in holes in trees formed by beetle larvae. Each hole, called a gallery, will house up to ten females and one male. Tree weta are nocturnal. Their diet consists of plants and small insects. The males, which have much larger jaws than the females, hiss and bite when threatened.
There are seven species of tree weta. The Auckland tree weta Hemideina thoracica (also called tokoriro) can be found throughout the North Island apart from the Wellington-Wairarapa region. The Wellington tree weta H. crassidens occupies Wellington, the Wairarapa, the northern portions of the South Island, and the West Coast. There is a tree weta H. trewicki in Hawke's Bay, H. femorata in Canterbury, and a rare H. ricta species in Banks Peninsula. The West Coast bush weta H. broughi largely overlaps with the Wellington tree weta on the West Coast. H. crassidens crassicruris was described from Stephens Island but is now recognized as H. crassidens. H. maori, the mountain stone weta, lives in the drier areas of the central South Island High Country. It abandoned life in trees millions of years ago in favour of crevices and cavities under rocks.
Mountain stone weta can survive being frozen for months at a time in a state of suspended animation down to temperatures of -10°C. This is because their haemolymph (the insect equivalent of blood) contains special proteins which prevent ice from forming in their cells.
When the territories of species overlap, they may interbreed, although offspring are sterile.
[edit] Tusked weta
Tusked weta are distinctive because of the males having long curved tusks projecting forward from their jaws. The tusks are used to push an opponent; they are not used for biting. The females are similar to ground weta. Tusked weta are mainly carnivorous, eating worms and insects. They consist of three species: the Northland tusked weta Hemiandrus monstrosus, the Middle Island tusked weta Motuweta isolata, and a newly-discovered species called the Raukumara tusked weta, Motuweta riparia. The Northland tusked weta lives in tree holes similar to tree weta. The Middle Island tusked weta, also called the Mercury Island tusked weta after the islands on which it lives, was only discovered in 1970. It is a ground-dwelling weta, covering its shallow burrows with leaves. The Middle Island weta is the most endangered weta species and a Department of Conservation breeding program is establishing new colonies on other islands of the Mercury Island group. The Raukumara was discovered even more recently, in 1996, in the Raukumara Range near the Bay of Plenty. There are probably more species still to be identified.
[edit] Ground weta
Ground weta are classified in the genus Hemiandrus along with some tusked weta.
[edit] Cave weta
The sixty species of cave weta have extra-long antennae, longer legs, a passive demeanour and deafness. Cave weta may be active within the confines of their caves during the daytime. They are classified in the genus Pachyrhamma (syn. Gymnoplectron) of the family Rhaphidophoridae, thus making them distant cousins of the other types of weta.
[edit] Conservation
Although the weta had native predators in the form of birds, reptiles and bats before the arrival of humans, introduced species such as cats, hedgehogs, rats (including kiore) and mustelids have caused a sharp increase in the rate of predation. They are also vulnerable to habitat destruction caused by humans and modification of their habitat caused by introduced browsers. New Zealand’s Department of Conservation considers that 16 of the 70 species of weta are now at risk. Programmes to prevent extinctions have been implemented since the 1970s.
[edit] Human ideas about weta
Māori considered weta flesh to be a delicacy. They also prized the carapaces of the larger species, which could be softened to a leathery consistency by boiling them in the acidic water of volcanic springs and used for food storage when journeying[citation needed].
For many New Zealanders today, the weta represents the revulsion of creatures that creep and crawl in the dark.
[edit] Cultural references
- Peter Jackson's workshop is named Weta Workshop and his digital studio is named Weta Digital; his 2005 remake of King Kong features creatures bearing a strong physical resemblance to wetas, called Weta-Rexes.
- Weta is also the name of a now-disbanded rock group from the late 1990s, early 2000s.
- The Wetas is also the name of a now-disbanded rock group, from 1980.
[edit] References
- Johns, P. M. (1997). "The Gondwanaland weta: family Anostostomatidae (formerly in Stenopelmatidae, Henicidae or Mimnermidae): nomenclatural problems, world checklist, new genera and species". Journal of Orthoptera Research 6: 125-138.
- Steve Trewick; Mary Morgan-Richards. New Zealand Invertebrate Speciation. Retrieved on 2006-05-08.
- Greg H Sherley (1998). Threatened Weta Recovery Plan. Department of Conservation. Retrieved on 2006-05-09.
