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Giant wētā
Giant wētā are several species of wētā in the genus Deinacrida of the family Anostostomatidae. Giant wētā are endemic to New Zealand and all but one species are protected by law because they are considered at risk of extinction.
There are eleven species of giant wētā, most of which are larger than other wētā, despite the latter also being large by insect standards. Large species can be up to 7 cm (3 in), not inclusive of legs and antennae, with body mass usually no more than 35 g (1.2 oz). One gravid captive female reached a mass of about 70 g (2.47 oz), making it one of the heaviest insects in the world and heavier than a sparrow. This is, however, abnormal, as this individual was unmated and retained an abnormal number of eggs. The largest species of giant wētā is the Little Barrier Island giant wētā, also known as the wētāpunga.
Giant wētā tend to be less social and more passive than other wētā. Their genus name, Deinacrida, means "terrible grasshopper", from the Greek word δεινός (deinos, meaning "terrible", "potent", or "fearfully great"). They are found primarily on New Zealand offshore islands, having been almost exterminated on the mainland islands by introduced mammalian pests.
Most populations of giant wētā have been in decline since humans began modifying the New Zealand environment. All but one giant wētā species is protected by law because they are considered at risk of extinction. Three arboreal giant wētā species are found in the north of New Zealand and now restricted to mammal-free habitats. This is because the declining abundance of most wētā species, particularly giant wētā, can be attributed to the introduction of mammalian predators, habitat destruction, and habitat modification by introduced mammalian browsers. New populations of some wētā have been established in locations, particularly on islands, where these threats have been eliminated or severely reduced in order to reduce the risk of extinction. Deinacrida heteracantha, and D. fallai are found only on near-shore islands that have no introduced predators (Te Hauturu-o-Toi and Poor Knights Island). The closely related species D. mahoenui is restricted to habitat fragments in North Island.
Two closely related giant wētā species are less arboreal. Deinacrida rugosa is restricted to mammal-free reserves and D. parva is found near Kaikōura in the South Island of New Zealand.
Many giant wētā species are alpine specialists. Five species are only found at high elevation in South Island. The scree wētā D. connectens lives about 1,200 m (3,900 ft) above sea level and freezes solid when temperatures drop below −5 °C (23 °F). Though the alpine species tend to be smaller on average than those other ground dwelling species.
Giant wētā are observed to be a largely solitary genus, with little aggregation seen in mature individuals. Most species within the Deinacrida genus exhibit scramble competition polygyny, where male wētā travel to find mature females within an area. Males of species such as the alpine Scree Wētā (Deinacrida connectens) aim to detect as many females as possible to mate with, increasing their reproductive success. Strong phenotypic selection for movement ability benefits reproductive success of the males, as individuals who can cover greater distances are likely to gain more access to a greater quantity of females.
Research suggests a correlation between body size of the female Cook Strait giant wētā (Deinacrida rugosa) and quantities of sperm deposited by their male mates. Male wētā produce spermatophores (small packets containing sperm) which are transferred to the female wētā during the process of copulation. However, it has been established that males are transferring a higher quantity of spermatophores to the lighter females, when compared to their heavier counterparts, suggesting an intentional allocation of reproductive effort. Due to the scramble competition polygyny being prevalent in giant wētā populations, and larger females participating in more mating behaviours, there is an increased competition between the males mating with larger females. This is because the larger female wētā presumably mate more frequently, increasing competition between individual males for paternity. Previously, it was thought that male wētā would allocate more of their reproductive energy to larger females, as a lot of larger female invertebrates are more fertile/can produce a higher quantity of offspring at one time. However, this study indicates males may choose to supply the smaller females with more spermatophores as a way to ensure paternity and decrease the risk of sperm competition, which may also be true of other giant wētā species.
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Giant wētā
Giant wētā are several species of wētā in the genus Deinacrida of the family Anostostomatidae. Giant wētā are endemic to New Zealand and all but one species are protected by law because they are considered at risk of extinction.
There are eleven species of giant wētā, most of which are larger than other wētā, despite the latter also being large by insect standards. Large species can be up to 7 cm (3 in), not inclusive of legs and antennae, with body mass usually no more than 35 g (1.2 oz). One gravid captive female reached a mass of about 70 g (2.47 oz), making it one of the heaviest insects in the world and heavier than a sparrow. This is, however, abnormal, as this individual was unmated and retained an abnormal number of eggs. The largest species of giant wētā is the Little Barrier Island giant wētā, also known as the wētāpunga.
Giant wētā tend to be less social and more passive than other wētā. Their genus name, Deinacrida, means "terrible grasshopper", from the Greek word δεινός (deinos, meaning "terrible", "potent", or "fearfully great"). They are found primarily on New Zealand offshore islands, having been almost exterminated on the mainland islands by introduced mammalian pests.
Most populations of giant wētā have been in decline since humans began modifying the New Zealand environment. All but one giant wētā species is protected by law because they are considered at risk of extinction. Three arboreal giant wētā species are found in the north of New Zealand and now restricted to mammal-free habitats. This is because the declining abundance of most wētā species, particularly giant wētā, can be attributed to the introduction of mammalian predators, habitat destruction, and habitat modification by introduced mammalian browsers. New populations of some wētā have been established in locations, particularly on islands, where these threats have been eliminated or severely reduced in order to reduce the risk of extinction. Deinacrida heteracantha, and D. fallai are found only on near-shore islands that have no introduced predators (Te Hauturu-o-Toi and Poor Knights Island). The closely related species D. mahoenui is restricted to habitat fragments in North Island.
Two closely related giant wētā species are less arboreal. Deinacrida rugosa is restricted to mammal-free reserves and D. parva is found near Kaikōura in the South Island of New Zealand.
Many giant wētā species are alpine specialists. Five species are only found at high elevation in South Island. The scree wētā D. connectens lives about 1,200 m (3,900 ft) above sea level and freezes solid when temperatures drop below −5 °C (23 °F). Though the alpine species tend to be smaller on average than those other ground dwelling species.
Giant wētā are observed to be a largely solitary genus, with little aggregation seen in mature individuals. Most species within the Deinacrida genus exhibit scramble competition polygyny, where male wētā travel to find mature females within an area. Males of species such as the alpine Scree Wētā (Deinacrida connectens) aim to detect as many females as possible to mate with, increasing their reproductive success. Strong phenotypic selection for movement ability benefits reproductive success of the males, as individuals who can cover greater distances are likely to gain more access to a greater quantity of females.
Research suggests a correlation between body size of the female Cook Strait giant wētā (Deinacrida rugosa) and quantities of sperm deposited by their male mates. Male wētā produce spermatophores (small packets containing sperm) which are transferred to the female wētā during the process of copulation. However, it has been established that males are transferring a higher quantity of spermatophores to the lighter females, when compared to their heavier counterparts, suggesting an intentional allocation of reproductive effort. Due to the scramble competition polygyny being prevalent in giant wētā populations, and larger females participating in more mating behaviours, there is an increased competition between the males mating with larger females. This is because the larger female wētā presumably mate more frequently, increasing competition between individual males for paternity. Previously, it was thought that male wētā would allocate more of their reproductive energy to larger females, as a lot of larger female invertebrates are more fertile/can produce a higher quantity of offspring at one time. However, this study indicates males may choose to supply the smaller females with more spermatophores as a way to ensure paternity and decrease the risk of sperm competition, which may also be true of other giant wētā species.