Giant hawker facts for kids
Quick facts for kids Giant hawker |
|
|---|---|
 |
|
| Artist's rendition of a female Tetracanthagyna plagiata | |
| Conservation status | |
| Scientific classification | |
| Synonyms | |
|
Gynacantha plagiata Waterhouse, 1877 |
The giant hawker (Tetracanthagyna plagiata), also known as the gigantic riverhawker, is a very large type of dragonfly. It belongs to the Aeshnidae family, which includes many well-known hawker dragonflies. You can find this amazing insect in parts of Southeast Asia, especially in a region called Sundaland. This includes countries like Thailand, Malaysia, Singapore, Sumatra, and Borneo.
The giant hawker is special because it's the heaviest of all living Odonata (which includes both dragonflies and damselflies). It's also the second largest Odonate by wingspan, only a little smaller than the damselfly Megaloprepus caerulatus. In fact, it's the biggest living dragonfly! Its wings can spread up to 163 millimeters wide. That's almost as long as a standard ruler!
Contents
What Does the Giant Hawker Look Like?
The giant hawker is a big dragonfly with a black body and large, clear wings. Its main body part, called the thorax, is black. On the sides of its thorax, there are two light yellowish stripes. These stripes help tell it apart from a similar dragonfly, Tetracanthagyna brunnea, which has reddish-brown stripes.
The giant hawker's belly, or abdomen, is reddish-brown and shaped like a tube. It can be about 100 millimeters (about 4 inches) long. The abdomen gets narrower towards the end. The wings of the giant hawker can have different patterns. Males and some females have dark streaks along the front edge of their wings. Only a few of these dragonflies don't have these dark bands.
Differences Between Males and Females
Male and female giant hawkers look quite similar, but there are a few key differences. Females are usually bigger than males. For example, a female's hindwings can be 80-84 millimeters long, while a male's hindwings are about 76 millimeters long. Also, female giant hawkers often have dark brown patches near the tips of their wings, which males usually don't have.
The Largest Dragonfly
The giant hawker is known for its impressive size. It is the heaviest living Odonate. It is also the largest living dragonfly (a group called Anisoptera). Only one other Odonate, the damselfly Megaloprepus caerulatus, has a larger wingspan.
Giant hawkers can have a wingspan of up to 163 millimeters. Their body length can reach 100 millimeters. This makes T. plagiata the largest living dragonfly, even bigger than Petalura ingentissima, which has a wingspan of 162 millimeters. Scientists generally agree that female giant hawkers are the heaviest living Odonates.
Some studies have measured the wingspan of giant hawkers in museums. Specimens at the Lee Kong Chian Natural History Museum had wingspans between 134 and 144 millimeters. Another report mentioned a wingspan of 160 millimeters. This confirms that the giant hawker is indeed the largest dragonfly in Southeast Asia.
Giant Hawker Life Cycle
Dragonflies go through different stages in their lives, from egg to adult. The giant hawker has a fascinating life cycle.
Laying Eggs
Female giant hawkers lay their eggs in rotting logs or other soft, moss-covered places near streams. They use a special tool called an ovipositor to insert their eggs into the wood. Before laying, the female might scrape the surface of the log for a minute. She will also arch her abdomen. One female was seen doing this at the MacRitchie Reservoir in Singapore, laying her eggs about 150 centimeters above the water.
Larva Stage
For a long time, scientists didn't know what the larvae (young stage) of the giant hawker looked like. But in 2010, researchers found and studied them. They found the larvae in slow-moving forest streams in Singapore's Central Catchment Nature Reserve.
Giant hawker larvae are large and have a unique look. Their heads have a distinct, bumpy shape. Their legs are short and strong, good for grabbing things. Unlike some other dragonfly larvae that actively hunt, giant hawker larvae are ambush predators. This means they hide and wait for their prey. They often look like a stick to blend in with their surroundings.
In captivity, these larvae ate live shrimp, small fish, and worms. In the wild, they likely eat different types of shrimp, small fish like catfish, and tadpoles. The shape of their mouthparts suggests they are good at catching larger prey.
Adult Behavior
Adult giant hawkers are most active during dawn and dusk. This is called a crepuscular lifestyle. Like other hawker dragonflies, they are often drawn to lights at night.
Where Do Giant Hawkers Live?
The giant hawker lives in the Oriental region of Southeast Asia, specifically in the area known as Sundaland. You can find them in:
They have been recorded on the islands of Sumatra and Borneo. They are also found in Singapore, where they are the only type of Tetracanthagyna dragonfly on the island. They have also been seen in the state of Johor in Peninsular Malaysia.
Giant Hawker Habitat
Giant hawker larvae live in slow-moving streams within secondary forests. These streams are usually about 1 meter wide and 0.6 meters deep. Their bottoms are a mix of sand and mud. The streams also have lots of organic material, like tree branches and fallen leaves. Female larvae are found in similar places, often with plants like sedges and ferns in the water, and trees providing shade.
Adult giant hawkers live in both primary (old growth) and secondary (regrowing) lowland forests.
Protecting the Giant Hawker
In 2010, the IUCN Red List looked at the giant hawker's conservation status. They decided it was of "Least Concern". This means it's not currently in great danger of disappearing. However, the report also mentioned some possible threats. These include:
- Logging in their forest homes
- Damage to their environment from mining
- Plantations for wood and paper pulp
In Singapore, the giant hawker was once thought to be very rare. An older report listed it as "rare" in the Nee Soon Swamp Forest. However, more recent observations show that the giant hawker has been seen in other parts of Singapore's Central Catchment Nature Reserve. In 2016, its status in Singapore was updated to "Restricted & Uncommon," and it was listed as a "Vulnerable" species. This means it needs careful watching to ensure its survival.
See also
- Meganeuropsis permiana and Meganeura monyi, very old, giant prehistoric dragonflies
- Megaloprepus caerulatus, the largest Odonate by wingspan (191 millimeters)
- Petalura ingentissima, the second largest dragonfly by wingspan (162 millimeters) and longest by body length (125 millimeters)
- Mecistogaster lucretia, the longest Odonate by body length (150 millimeters)
- Chlorogomphus papilio, a dragonfly with very wide wings
