Hemideina crassidens
| Hemideina crassidens | ||||||||||||
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Hemideina crassidens , male |
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| Hemideina crassidens | ||||||||||||
| ( Blanchard , 1851) |
Hemideina crassidens is an endemic endemic to New Zealand found long- antennae shrimp (Ensifera) from the family of Weta (Anostostomatidae). Since itcan be found in large numbers in the area of the capital Wellington and prefers to live on trees, it is called Wellington Tree Weta in English usage.
features
The adults of Hemideina crassidens reach a body length of 40 to 60 millimeters and weigh 3.0 to 6.0 grams. Both sexes are wingless. The tergum is armored. The abdomen is alternately dark brown and yellow-gray stripes. The legs are provided with thorns, which are particularly strong on the rearmost pair of legs. The antennae are very long. The long, slightly curved ovipositor in females is striking . In the males, the head and mandibles are particularly strong.
Distribution and occurrence
The species occurs in the south of the North Island and the northern and northwestern part of the South Island of New Zealand. It lives there on trees and sometimes also populates gardens.
Way of life
The nocturnal weta feed on small insects and plant matter. They form polygynous communities, with one male living together with up to ten females. A tree hole is usually used as a place to stay. Here, the males with the strong mandibles further develop broken or slightly rotten fractures that were previously damaged by beetle larvae. Sometimes up to ten young animals of both sexes live in these caves. The animals communicate with one another through stridulation . If a foreign male intrudes into an occupied territory, the territory owner first tries to drive away the intruder by threatening with his thorny hind legs. If this is unsuccessful, the powerful mandibles are used, which can sometimes lead to serious injuries to the limbs. However, deaths are rare as the weaker animal usually withdraws in time.
development
The females lay the black, 5.0 to 6.5 millimeter long eggs in April and May by means of the ovipositor under the earth's surface. The larvae hatching in New Zealand's spring (September to November) molt up to ten times before they are fully grown. This development extends over one to two years.
Cold resistance
A special feature of Hemideina crassidens is its resistance to cold ( thermoregulation # Poikilotherm in cold surroundings ). Like the species Hemideina maori that lives in the highlands and the Hemideina thoracica that lives in the lowlands, it is able to form ice crystals inside during severe frost without damaging the body tissue or organs. It can be assumed that ice nucleating agents are contained in the hemolymph . The ice crystals thaw again when the temperature rises and the animals continue to live as before.
Danger
Hemideina crassidens is not yet officially recorded by the World Conservation Organization ( IUCN) , but many populations of these flightless terrors are threatened by deforestation measures and introduced mammal species.
Individual evidence
- ↑ Steven A. Trewick & Mary Morgan-Richards: On the distribution of tree weta in the North Island, New Zealand , Journal of the Royal Society of New Zealand, 25 (4), 1995, pp. 485-493
- ↑ Hemideina crassidens, The Wellington Tree Weta
- ↑ Laurence H. Field & FC Rind: Stridulatory behavior in a New Zealand weta, Hemideina crassidens , Journal of Zoology, London, 1992, 228 (3), pp. 371-394
- ^ RG Ordish: Aggregation and communication of the Wellington weta Hemideina crassidens (Blanchard) (Orthoptera: Stenopelmatidae) , New Zealand Entomologist, 1992, 15, pp. 1-8
- ^ Taranaki Educational Resource
- ↑ Ice nucleation and freezing tolerance
Web links
- gbif.org - Global Biodiversity Information Facility
- teara.govt.nz - Tree Weta in The Encyclopedia of New Zealand