Deinacrida heteracantha
Deinacrida heteracantha | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Orthoptera |
Suborder: | Ensifera |
Family: | Anostostomatidae |
Genus: | Deinacrida |
Species: | D. heteracantha
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Binomial name | |
Deinacrida heteracantha White, 1842
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Deinacrida heteracantha, also known as the Little Barrier giant wētā or wētāpunga (Māori: wētāpunga),
Description
D. heteracantha can weigh up to 70 g, but on average weighs between 9–35 g. Average body length is around 75 mm (3 inches).[3][4][5] It is a sexually dimorphic species, with the females being much larger than the males. These large wētā have a broad body and a round head, along with short mandibles.[4] Compared to other cricket species wētā have relatively short antennae, but can deliver a strong kick with their hind legs. They are generally wingless.[3] The species is mainly herbivorous and feeds on forest foliage.[4]
Habitat
D. heteracantha are arboreal forest insect dwellers found on Little Barrier Island which lies off the coast of New Zealand. This island is only 3,083 hectares (7,620 acres) in size.
Behaviour
As adults these giant wētā live a nomadic lifestyle.
Life cycle and reproduction
The life cycle of D. heteracantha is not tied to the seasons. They can live for up to two years. Eggs are laid in the summer months from October to December. The eggs will then hatch in March and April of the following year. D. heteracantha mate most months out of the year except for the winter months from June–August. Copulation will start in the morning and continue throughout the day. During copulation the spermatophore from the male is inserted into the female's subgenital plate. Females lay their eggs at night into moist soil. Each egg is laid singly or in groups of five in area that is about 15 cm2 and about 2–3 cm deep. Females produce an indefinite amount of eggs. Females lay eggs for the rest of their lives, but only a limited number of them are fertilised during each copulation. The eggs incubate on average for 125 days and only 36% of the eggs survive to hatch.[7]
After the eggs hatch there are ten
D. heteracantha show no courtship rituals. No
Sound generation
D. heteracantha possesses a
Threats
While D. heteracantha were commonly seen on Little Barrier Island in the 1950s, numbers have declined strongly since then. Predation rather than habitat destruction is regarded as the main cause for this.[10] Feral cats were present on the island until they were completely eradicated in the 1980s,[4] and may have fed on vulnerable juvenile D. heteracantha.[7]
Polynesian rats (Rattus exulans), or "kiore" in the Māori language, are one of the top predators of D. heteracantha, preying mostly on juveniles wētās which they kill during the night. An increase of the Polynesian rat population occurred after feral cats were eradicated. As saddlebacks prey on the wētā during the day, D. heteracantha are thus under constant predation pressure.[10] There is evidence suggesting that these rats have a negative impact on the population of these wētā, as is commonly the case with invasive rodents.[11] The removal of the kiore in 2004 was a success. The population size grew back each year and a four-fold increase was reported six years after the removal.[12]
Other predators include
Captive breeding and release
D. heteracantha is currently classified as
See also
References
- ^ . Retrieved 17 November 2021.
- ^ "Giant Wētā/Wētāpunga". New Zealand Department of Conservation. Retrieved 17 Jan 2019.
- ^ a b c Nasrecki, P. 2013. Grasshoppers and their relatives. Elsevier Inc. 3: 247-264.
- ^ a b c d e f g h Field, L.H. 2001. The Biology of Wetas, King Crickets and their Allies. New York: CABI Publishing.
- ^ ISSN 1082-6467.
- ^ Encyclopædia Britannica. 2015. Nomadism. Accessed November 20, 2015 from Link text
- ^ a b c d e Richards, A.O. 1973. A comparative study of the biology of the giant wetas Deinacrida heteracantha and D. fallai (Orthoptera: Henicidae) from New Zealand. Journal of Zoology 169: 195-236
- ^ Field, L.H. 1993. Structure and evolution of stridulatory mechanisms in New Zealand Wetas (Orthoptera: Stenopelmatidae). International Journal of Insect Morphology and Embryology (22): 163-183.
- ^ Field, L.H. 1981. Stridulatory structures and acoustic spectra of seven species of New Zealand wetas (Orthoptera: Stenopelmatidae). International Journal of Insect Morphology and Embryology (11): 39-51.
- ^ ISBN 0-478-018967.
- ^ St. Clair, J.J.H. 2011. The impacts of invasive rodents on island invertebrates. Biological Conservation (144): 68-81.
- ^ Green, C. J, G.W, Gibbs, and P.A, Barrett. (2011). Wetapunga (Deinacrida heteracantha) population changes following Pacific rat (Rattus exulans) eradication on Little barrier Island. IUCN, Gland, Switzerland: 305-308.
- ISSN 1171-8595. Archived from the original(PDF) on 29 January 2021. Retrieved 14 December 2015.
- ISSN 1171-8595.
- ^ Saxton, Amanda (2018-09-07). "The island life for hundreds of giant wētāpunga". Stuff. Archived from the original on 2018-12-01. Retrieved 2021-08-31.
- ^ "'A real homecoming': Wētāpunga, predating dinosaurs, return to NZ islands". RNZ. 2023-08-21. Retrieved 2023-08-31.
Further reading
- Colenso, W. 1881: On some new and undescribed species of New Zealand insects of the orders Orthoptera and Coleoptera. Transactions and Proceedings of the New Zealand Institute, 14: 277–280. [publication date: 1882?] BUGZ
- Gibbs, G.W. 1999: Four new species of giant weta, Deinacrida (Orthoptera: Anostostomatidae: Deinacridinae) from New Zealand. Journal of the Royal Society of New Zealand, 29(4): 307–324.
- Trewick, S.A.; Morgan-Richards, M. 2004: Phylogenetics of New Zealand's tree, giant and tusked weta (Orthoptera: Anostostomatidae): evidence from mitochondrial DNA. Journal of Orthoptera research, 13(2): 185–196.
- Watt, J.C. 1963: The rediscovery of a giant weta, Deinacrida heteracantha, on the North Island mainland. Archived 2011-09-29 at the
External links
- Deinacrida heteracantha discussed on RNZ Critter of the Week, 30 August 2022