Redback spider facts for kids
Quick facts for kids Redback spider |
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| An adult female redback spider. | |
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| An adult male, which is much smaller than the female. | |
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The redback spider (Latrodectus hasselti), also known as the Australian black widow, is a highly venomous spider. It is believed to have come from Australia but now lives in Southeast Asia and New Zealand. It has even been found in other countries after being accidentally shipped in crates.
The redback is part of the Latrodectus genus, which includes all widow spiders. The adult female is easy to spot. She has a round, black body with a bright red stripe on her back. On her belly, she has a red or orange mark shaped like an hourglass. Females are about 10 millimeters long. The male is much smaller, only about 3 to 4 millimeters long.
Redback spiders are mostly active at night. The female builds a messy-looking web in warm, sheltered places, often near or inside houses. She eats insects, other spiders, and even small animals like lizards that get caught in her web.
To kill her prey, she bites it with her two fangs, injecting a powerful venom. She then wraps the prey in silk and sucks out the liquefied insides. Sometimes, she first squirts a type of "superglue" from her spinnerets to trap the prey before wrapping it in silk.
The redback is one of the few spiders in Australia that can be seriously harmful to humans. Because it likes to live near people, it is responsible for many serious spider bites. An antivenom was created in 1956 to treat these bites.
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Naming and Classification
The spider gets its common name "redback" from the red stripe on its back. It is closely related to other widow spiders, like the famous black widow of North America and the katipō of New Zealand.
Swedish scientist Tamerlan Thorell first described the redback spider in 1870. For a long time, scientists debated whether the redback was its own species or a subspecies of the black widow. However, modern DNA studies have confirmed that the redback is a distinct species.
What Do Redback Spiders Look Like?
The adult female redback has a body about 1 centimeter long. Her abdomen is a shiny black with the famous red stripe on top and an hourglass shape underneath. Sometimes, a female might have brownish coloring or no stripe at all. Her head and fang area, called the cephalothorax, is much smaller than her abdomen.
Young redback spiders are grey with dark spots. They get darker each time they shed their skin as they grow. Young females also have extra white markings on their abdomens. These bright colors may act as a warning to predators.
The male redback is tiny compared to the female. He is light brown with white markings on his back and a pale hourglass shape on his belly.
How Redback Spiders Behave
The redback spider is nocturnal, meaning it is active at night. The female usually stays hidden during the day and builds her web at night. She will often live in the same spot for most of her life.
The Web
A redback's web is a messy tangle of strong silk. The web might look random, but it is cleverly designed to catch prey. The back of the web has a funnel-shaped area where the spider hides with her egg sacs.
From this funnel, sticky threads run down to the ground. These threads act like tripwires. When an insect or small animal touches a thread, it gets stuck. The thread breaks from the ground and pulls the prey into the air, where the spider can attack it.
What They Eat
Redbacks mostly eat insects, but their strong webs can trap larger animals like small lizards and even, on rare occasions, snakes. They are often found near homes because lights and garbage attract insects, which are the spiders' main food source.
When prey is caught, the redback approaches and squirts a sticky liquid silk to immobilize it. Then, she bites the victim many times and wraps it in more silk. The venom liquefies the prey's insides, which the spider then sucks out.
Male spiders and young spiderlings sometimes live near the female's web and eat her leftovers.
The Life Cycle of a Redback Spider
After mating, the female can store the male's sperm for up to two years. She can use it to fertilize several batches of eggs. She lays her eggs in a white, round, silken sac. Each sac contains about 250 eggs.
Spiderlings hatch after about 8 days. They stay inside the egg sac for about a week, then emerge. Male spiders become adults in about 45 to 90 days. Females take longer, about 75 to 120 days. Females can live for two to three years, while males only live for about six or seven months.
Young spiders leave their mother's web by a process called "ballooning." They climb to a high point, release a long thread of silk, and let the wind carry them away to a new home.
Reproduction
When a male spider finds a female, he performs a strange courtship dance. During mating, the male does a "somersault" and places his abdomen over the female's fangs. In most cases, the female eats the male while they are mating.
This sacrifice helps the male in two ways. First, it allows him to mate for a longer time, which means he can fertilize more of her eggs. Second, a female who has eaten a male is less likely to mate with another male. This ensures that the first male's genes are passed on.
Where Do Redback Spiders Live?
The redback spider is found all over Australia, except in the hottest deserts and coldest mountains. It originally lived in the dry parts of South and Western Australia. However, it has spread with human help.
Redbacks love living in and around human homes. They build their webs in dry, dark, and sheltered places. Common spots include sheds, under toilet seats, in empty cans, inside old tires, and in piles of wood or bricks. They are also found in mailboxes and children's toys left outside.
Because they travel well in cargo, redbacks have spread to other countries. They have established colonies in New Zealand, Japan, and the United Arab Emirates. They have also been found in greenhouses in Belgium.
Bites and Treatment
The redback spider is one of Australia's most well-known venomous creatures. The larger female is responsible for nearly all bites to humans. The male is much smaller, and his bite usually causes only mild, short-lived pain.
Most bites happen during the warmer months. They often occur when someone accidentally puts their hand or foot near a spider's web, like when gardening or cleaning up clutter.
Venom and Symptoms
A redback's venom contains a powerful toxin that affects the nervous system. This is called a neurotoxin. A bite from a redback can cause a condition called latrodectism.
The bite itself might feel like a small pinprick. Within an hour, severe pain can develop at the bite site. The area might also start to sweat. Pain, redness, and swelling can spread up the limb. Other symptoms can include nausea, vomiting, headache, and high blood pressure. Severe pain can last for more than 24 hours.
While very painful, redback bites are not usually life-threatening for healthy adults. Children and the elderly are at a higher risk of severe symptoms.
How Bites Are Treated
For most bites, simple first aid is enough. Applying an ice pack to the area and taking pain-relief medicine like paracetamol can help. You should not apply a pressure bandage, as this can make the pain worse.
If the pain is severe or if systemic symptoms (symptoms affecting the whole body) develop, you should go to a hospital. Doctors may use stronger pain medicine to help.
An antivenom for redback bites has been available since 1956. In the past, it was given to anyone with severe symptoms. Today, doctors are more likely to manage the pain with other medicines first. Studies have shown that the antivenom may not work much better than a placebo (a dummy treatment) for pain relief.
No deaths from redback bites have been confirmed in Australia since the antivenom was introduced.
Redback Spiders in Popular Culture
The redback spider is a well-known symbol in Australia.
- The country singer Slim Newton had a hit song in 1973 called "The Redback on the Toilet Seat."
- A giant sculpture of a redback spider is one of Australia's big things and can be found in Queensland.
- The spider has been used as a logo for sports teams, a brand of beer, and a company that makes work boots.
Images for kids
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Redback Spider
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Redback spider - Latrodectus hasselti
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Female in its web
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The distinctive red stripe of the adult female
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See also
In Spanish: Araña de lomo rojo para niños
- List of common spiders of Australia
- Spiders of Australia
