Moving our focus a couple hemispheres away, the country of New Zealand is composed of a collection of islands southwest of Australia, in between the Tasman Sea and the South Pacific Ocean. This island country is home to some of the world’s most pristine landscapes (as attested to in The Lord of the Rings series) and a bountiful collection of unique endemic island species. Islands are probably one of the most fascinating places to observe the processes of evolution because their isolated nature yields some rare adaptations as species become genetically isolated and fill the niches of their island homes usually without many predators. An ancient group of insects descended from grasshoppers and crickets, called wētā, are a perfect example of this explicit island evolution, as they speciated into more than 70 different species, which are all endemic to the islands of New Zealand. Wētā are relatives of the species that once inhabited Gondwana. Referred to by scientists as living fossils, they made their way to New Zealand, before New Zealand formed the group of isolated islands it is today.
The giant wētā is just one of 5 different groups of wētā that can be found in New Zealand. There are eleven species of giant wētā, all of which are in the genus Deinacrida (deinos, greek meaning: terrible or devil, similar to dinosaur meaning terrible lizard probably because they look like something out of the movie, Infestation!). We are going to focus in on the giant wētā with arguably the coolest name, wētāpunga (Maori meaning: god of ugly things) or the Little Barrier Island giant wētā, because it is the largest wētā in existence and its conservation issues are reflective of the giant wētā group as a whole.
wētāpunga / Little Barrier Island giant wētā
Coming in at 71 grams, heftier than a sparrow, one of the heaviest documented insects in the world was a female wētāpunga found on Little Barrier Island. Even though this wētāpunga is probably an extreme example, the average weight of this species is still massive in contrast to the insects you are probably accustom to. With an average weight of 9-35 grams, it is similar in size to a mouse. The species is usually about 75 mm in length, but thankfully wētāpunga are awfully gentle in comparison to their smaller wētā family members. Additionally, wētāpunga are sexually dimorphic, meaning the males and females have different appearances with the females being much larger than the males. Wētā share the characteristics of most crickets and grasshoppers in that it obtains oxygen through holes in its exoskeleton because it doesn’t have lungs. The holes connect to tubes that pump oxygen throughout their body.
Weta chirping. www.youtube.com
And they produce sounds the same way that other crickets do: by rubbing appendages together.
Likewise to the whole wētā lineage, the Little Barrier Island giant wētā is extremely old. Fossil records from the Triassic period indicate that wētā have changed little in their 19 million years of existence. It is well understood that they filled the role of rodents before land mammals were introduced to New Zealand, but changing behaviors/diets adapted with the changing environment over time.
Wētāpunga is mainly herbivorous and feeds on forest foliage, however, one study on captive wētā observed a wētāpunga feeding on other arthropods and on other wētāpunga that were molting and mating, but this has never been witnessed outside of captivity. In the wild, they show a preference for native island plants with large leaves such as karaka, karamu, māmāngi, māhoe, and kohekohe. As arboreal forest dwellers, they rely on second growth forests and mid-level forests for habitat. They often occupy cavities and the spaces created by loosened bark on Mahoe and Pohutubawa trees. Most behaviors have been observed at night, making this arthropod primarily nocturnal. In the cover of darkness, the wētāpunga can hide from tuatara, kiwi, saddleback, and laughing owls, who are their native predators. During the day, the wētāpunga tries hide its gigantic body in dead foliage in the bottom canopy of the forest. Wētāpunga commonly migrate throughout their lifetime with males traveling up to 16 meters per night and females averaging about 8 meters.
Not only is this insect large, but it also lives a remarkably long life. They can live up to 2 years, yet they only live in adulthood for about 6-9 months. Wētāpunga undergo 11 “instars” before reaching adulthood, meaning they molt their exoskeleton 11 times in order for them to grow to their massive size (probably why people named them the God of ugly). About 1-2 months after maturity, wētāpunga will mate frequently and females will lay many groups of cigar-shaped eggs in soft organic soil on the forest floor. Copulation occurs subsequently after a night of stalking where the male follows behind the female at a distance of about 25 cm while waving his antennae erratically. Then, if he can stay on her trail, they pair up and in the morning they perform the one act they are known for doing in the light of day, mating.
Up next we will discuss the environmental issues that the wētāpunga faces: wētāpunga: the God of ugly things is in need of its beautiful land — The Environmental Issue
If you would like to check out more animals on the Endangered Species List on your own, please visit the U.S. Fish and Wildlife Service’s list of Threaten/Endangered Species in the U.S. and Foreign Countries.
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