Bluff weta facts for kids
Quick facts for kids Bluff wētā |
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| Conservation status | |
 Sparse (NZ TCS) |
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| Scientific classification | |
| Genus: |
Deinacrida
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| Species: |
elegans
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The Deinacrida elegans, also known as the Bluff wētā, is a special type of wētā. It belongs to the Anostostomatidae family. This amazing insect is found only in New Zealand, meaning it is endemic to the country.
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What Does the Bluff Wētā Look Like?
The Bluff wētā is one of New Zealand's biggest land insects. It's part of a group of 11 different wētā species called Deinacrida. Seven of these species, including the Bluff wētā, live in the South Island. They are known for their size and unique looks.
This wētā is quite large and has a striking appearance. Its Latin name, elegans, means "neat and elegant," which suits it well! It has long legs and is a steel-grey color. Its legs have cool red, black, and white stripes. Male Bluff wētā weigh about 80 grams. Females are much bigger, weighing between 114 and 165 grams.
The wētā's body has a brown, mirror-like pattern on its middle section (thorax). It has smooth, rounded, pale grey edges. Its black antennae are very long, about 2.5 times the length of its whole body. These stick out from its striped grey-brown head.
Young wētā, called juveniles, look a bit different from adults. They are mostly black with white spines and leg joints. As they grow up, they change to their adult colors of dark brown, red, and grey.
How to Identify a Bluff Wētā
The Bluff wētā is a moderately large, steel-grey insect. It has a long body shape. You can spot it by the distinctive red and black stripes on its upper legs (femora). Its lower hind legs (tibiae) are slender. They have 7 or 8 fixed spines, plus one movable spine on the inner row.
- Weight: Males weigh around 80 grams. Females are heavier, from 114 to 165 grams.
- Head: The antennae are black. The head, including the mouthparts, is one solid piece.
- Body: The middle part of the body (thorax) is wide. The main body sections (tergites) are smooth and a bit shiny. They are tan-brown in the middle with pale grey edges.
The wētā's body is made of repeating cylinder-like parts. These are divided into three main sections:
- Head: This section gathers information about its surroundings. It helps the wētā feel, see, taste, and smell.
- Thorax: This section is for moving around.
- Abdomen: This section is used for reproduction.
The Head of a Wētā
The head is very important for an insect. It's the first part to find food, sense danger, or spot a possible mate. It holds the wētā's sense organs for touch, sight, taste, and smell. Even though the head looks like it has six parts, they are all joined together into one strong "head capsule." This capsule holds the antennae, eyes, and mouthparts. Because the head is rigid, the wētā's "face" always looks the same!
The Thorax of a Wētā
A short neck connects the head to the thorax. The thorax in all insects has three parts. You can clearly see these parts along the wētā's back. Each part of the thorax has a pair of legs. Bluff wētā do not have wings on their thorax.
The Abdomen of a Wētā
The wētā's abdomen is the largest and simplest part of its body. It is round and smooth. It doesn't have any extra parts except at its very end. Its main jobs are internal, holding the wētā's reproductive organs and digestive system. It can also expand, like a container.
Where Do Bluff Wētā Live?
Global Range
Bluff wētā are found only in New Zealand. They are endemic, meaning they naturally live nowhere else in the world.
New Zealand Range
You can find Bluff wētā in two main areas in New Zealand. One area is the Kaikōura region, including both the coastal and inland mountain ranges. The other area is at Mount Somers in South Canterbury. Wētā found at Mount Somers are sometimes called "Mt Somers wētā," but they are the same species, Deinacrida elegans.
They can also be found in places like Middlehurst Station, the Inland Kaikoura Range, the Hapuku River, and the Seaward Kaikoura Range. In the Kaikoura Ranges, wētā have not been found below 1100 meters. It seems they prefer to live in high mountain areas.
Habitat Preferences
The Deinacrida elegans is an excellent rock climber, thanks to its long legs. It lives on tall, rocky cliffs. You can find them deep inside dark, narrow cracks in the rocks. Sometimes, they are also found under thick, overhanging plants.
They prefer clean, dry, horizontal spaces between 800 and 1800 meters above sea level. These spaces allow the wētā to hide as far away from light as possible.
Life Cycle of the Bluff Wētā
Giant wētā, including the Bluff wētā, live for about two years. They become old enough to have babies (sexually mature) after one year.
During winter and colder months, Bluff wētā stay deep inside their rock dens. They do this to keep warm, especially when it snows. As the weather gets warmer, they move closer to the outside. They become more active in the summer months, from late December to February. This shows they are more active when temperatures are higher. This active period is also when they breed, so they need to move around more to find partners.
Mating
Wētā find partners using a method called 'scramble competition polygyny'. This means that when a female is ready to mate, she wanders around. A male will then be attracted to her. A chase might happen until the female chooses the male she wants to mate with. This is a peaceful way for them to find a partner. Other than mating, wētā usually don't show much social behavior. Even if you find more than one in the same crack, they usually keep to themselves.
Wētā don't form lasting pairs. So, adults spend a lot of effort finding partners. Giant wētā, which live mostly alone, need to find each other. They do this mainly when they are active at night. When a female is ready to mate, she releases a special smell called a pheromone. Males will then follow this scent trail to find her. The wētā's long antennae are very important for this.
Egg Laying
Wētā eggs can be laid in almost any month. April and May are often preferred. This is because the hard summer soil is softened by the autumn rains, making it easier to lay eggs. The eggs are about 6mm long and 1.5mm thick. They are dark brown and look a bit like small sausages.
The eggs stay in the soil over the winter. They hatch in October or November. The soil conditions are important during this long incubation time, but scientists don't fully understand them yet.
When the tiny young wētā hatches, it breaks out of the eggshell. Then, it struggles its way up to the soil surface. The hatchlings look just like miniature adult wētā. They have very long antennae and excellent jumping legs.
Moulting
Moulting, also called ecdysis, is when the wētā sheds its old outer skin (exoskeleton). The old skin opens along the back. The wētā then comes out with a new, soft exoskeleton. This whole process takes about 2 to 3 hours.
After moulting, when the wētā is in its nymph stage, it looks for a dark place. It needs time for its new, white-rose colored exoskeleton to become hard and get its adult color. This hardening process takes about 24 hours.
What Do Bluff Wētā Eat?
The Deinacrida elegans, like other wētā species in the South Island, mainly eats plants. This means they are herbivores. They mostly feed on the leaves of trees and shrubs. How they developed this eating habit is not fully understood. In the wild, wētā are mostly plant-eaters, but they are also known to eat insects sometimes. All types of giant wētā mainly eat leaves.
Wētā can be kept well in captivity. They can eat a diet of fresh carrots and leaves. However, if you give them a freshly killed grasshopper or even another wētā, they will happily switch from plants to eating these insects. In the wild, they don't get many chances to eat living insects. This is because they are not great hunters. Most of their animal diet comes from finding insects that are dying, dead, or not moving much.
Who Hunts the Bluff Wētā?
The Bluff wētā is currently considered "naturally uncommon" and "at risk." This means their numbers are not very high. If their population starts to drop, action needs to be taken right away. Rodents are the biggest threat to them right now.
Even though wētā have many places to hide in shrubs and steep, rocky cliffs, they are not completely safe. If the number of rodents increases quickly, people might need to control the rodent population.
Before humans arrived in New Zealand, wētā were hunted by native animals like tuatara, lizards, short-tailed bats, and birds. Even today, scientists have seen tuatara eating Deinacrida wētā. Wētā remains are often found in tuatara droppings.
After people settled in New Zealand, new mammal predators were brought in. These animals quickly became good at hunting wētā. Hedgehogs are one example of an introduced predator. These predators have learned how to quickly kill wētā. They can avoid or stop the wētā's defense moves. For example, a hedgehog can hold the wētā with its front paws. This stops the wētā from raising its hind legs to defend itself. Then, the hedgehog bites the wētā with its strong jaws.
Another way wētā try to avoid being eaten or escape bad conditions is by leaping away with their legs. Then, they roll up with their legs tucked in.
The morepork, a native owl, is the main native predator that hunts wētā at night. It can spot them sitting on tree trunks. The size of the wētā is not a problem for the morepork. Even parts of very large wētā have been found in morepork nests on Little Barrier Island.
New Zealand's Unique Ecosystem
New Zealand doesn't have many native mammals, except for native bats. This makes New Zealand's ecosystem very special. The wētā plays a big role in this unique environment. It acts like a small mammal, such as a mouse, on the forest floor.
Because of this, wētā have become very large, a process called gigantism. This happens when a group of animals living in an isolated place grows bigger than its relatives. This is often because there are fewer predators or a lot of food. So, the wētā is thought to be like a mouse in New Zealand's ecosystems. This is clear when you look at how wētā and mice are hunted and what they eat. Even though mice might not directly hunt wētā, the number of wētā goes down when mouse numbers are high. This is because they compete for food.
Interesting Fact
The Bluff wētā often has a slightly twisted abdomen. This seems to be related to its habitat, where it often squeezes itself into tight cracks. It has also been seen that Bluff wētā sometimes come out of their hiding places during the day to sunbathe!
Cultural Uses of the Wētā
Since wētā are found only in New Zealand, they have become a kind of local symbol. The wētā symbol is used in advertising and as a business tool. For example, Weta Digital is a famous special effects company started by Peter Jackson.
