Redback spider

The redback is a black spider.

The female has a red stripe on her back. She also has a red shape on her belly.

The male is much smaller than the female. She lives in a messy web. This web is often near our homes.

The spider catches bugs in her web. She uses a sticky silk to hold them. Then she eats the bugs for food. She can live for a long time.

The redback spider is a famous spider from Australia.

It is also called the Australian black widow. Female redbacks are easy to spot. They have a round, black body. A bright red stripe runs along their back.

They also have a red hourglass shape on their belly. The males are much smaller than the females.

Females build messy webs in warm, sheltered spots. These webs are often near human homes. The web is a tangle of strong silk.

It has sticky threads to catch prey. The spider eats insects and even small lizards.

When a bug hits the web, the spider uses silk to stick it down. It then bites the prey with its fangs. The venom turns the insides of the bug into liquid. The spider sucks up this liquid for food.

Redback spiders can be harmful to humans. Their venom can cause a lot of pain. Doctors have an antivenom to help people.

This map shows where they live around the world.

The redback spider is a famous and venomous arachnid.

People often call it the Australian black widow. It belongs to a group of spiders named Latrodectus. Most redbacks come from Australia. However, they are now found in many other places. They live in Southeast Asia, Japan, and New Zealand. They have even traveled in packing crates to the United States.

This spider is important to study because its bite can be serious for humans.

Female redbacks have a very distinct look. They have a round, black body. A bright red stripe runs along the top of their abdomen.

On their underside, they have a red or orange hourglass shape. The males look very different from the females. They are much smaller and are light brown.

Females usually live in a messy web in warm, sheltered spots. These webs are often found near or inside human homes. The female stays in her web mostly at night.

Catching food is a very interesting way for this spider to work. The female builds a tangle of strong silk.

Some threads act like trip wires to alert her to movement. When a bug hits the web, the spider squirts a sticky liquid. This liquid acts like superglue to hold the prey still.

The spider then bites the victim with its fangs. It injects venom that turns the insides of the prey into liquid. Finally, the spider sucks out the liquid for food.

Scientists have studied these spiders for a long time. A Swedish scientist named Tamerlan Thorell first described the redback in 1870. He found his specimens in central Queensland, Australia. He named the species Latrodectus hasselti to honor his colleague. Later, other scientists like Herbert Walter Levi studied how they are related to other spiders. In 1956, doctors made an antivenom to help people bitten by these spiders. This helps treat the pain caused by the venom.

Redback spiders have a busy life cycle. Females can live for two to three years. Males live for a shorter time, usually six or seven months.

After mating, a female can store sperm for up to two years. She uses it to lay several clutches of eggs. Each clutch has about 250 eggs inside a white silk sac. Baby spiders hatch after about eight days. They often stay in the egg sac for a week to feed.

Small spiderlings can even be quite hungry and may eat their siblings.

The redback spider, known scientifically as Latrodectus hasselti, is a highly venomous arachnid.

It is a member of the cosmopolitan genus Latrodectus, which includes the widow spiders. While it is believed to have originated in Australia, it has spread to many other regions. You can now find these spiders in Southeast Asia, Japan, and New Zealand. They have even been found in packing crates in the United States.

Because they often live in warm, sheltered spots near human homes, they are a significant species for medical study.

An adult female redback is very easy to recognize by her physical features. She has a spherical, deep black abdomen that may sometimes appear brownish. A prominent red or orange stripe runs along the dorsal aspect, which is the upper side of her body. On her underside, she displays a bright red or orange hourglass-shaped streak.

The male is much smaller than the female and looks quite different. He is light brown with white markings on the upper side of his abdomen. Female bodies are typically around 10 millimeters long, while males are significantly smaller.

The female builds a specific type of web called a gum-footed tangle web. This web is an irregular tangle of fine, strong silk threads. Some threads are placed strategically to act as trip wires to alert the spider to prey. These vertical strands run to ground attachments and snare animals. If a victim thrashes, weaker horizontal strands called guy lines may break. This action can actually haul the prey into the air. The spider usually stays in a funnel-like retreat area at the back of the web.

Catching prey involves a very specific, step-by-step biological process. First, the spider advances to about one leg's length from the target. She squirts a liquid, glutinous silk from her spinnerets to immobilize the victim. This substance acts much like superglue, sticking the prey's limbs to its own body. The redback then bites the victim repeatedly on the head, body, and leg segments. She injects a complex venom through her two fangs. This venom liquefies the insides of the prey. Finally, the spider hauls the victim to her retreat and sucks out the liquefied contents.

This process can take anywhere from 5 to 20 minutes.

Redback spiders have a complex life cycle and unique reproductive habits. After mating, the female stores sperm in specialized organs called spermathecae. She can use this stored sperm to fertilize several clutches of eggs up to two years later. Each clutch contains an average of 250 eggs housed in a round, white silken sac. Spiderlings hatch about 8 days after the eggs are laid. They may stay inside the sac for a week to feed on yolk. Females can live for two to three years, while males live only six to seven months.

The history of studying the redback involves many different scientists. Swedish arachnologist Tamerlan Thorell first described the species in 1870. He collected specimens from Rockhampton and Bowen in central Queensland. He named the species Latrodectus hasseltii to honor his colleague, A.W.M. van Hasselt. In 1959, arachnologist Herbert Walter Levi revised how we classify these spiders. He focused on the morphology, or physical shape, of female sexual organs. He originally reclassified the redback as a subspecies of the North American black widow. However, modern genetic studies have since confirmed the redback as a distinct species.

Redback venom is primarily neurotoxic to vertebrates, meaning it affects the nervous system. In humans, this can cause a condition called latrodectism. This syndrome often begins with severe pain around the bite site. The pain typically progresses up the bitten limb and can last for over 24 hours. Some people may experience localized sweating, nausea, vomiting, headache, or agitation. Because of the medical importance of these bites, an antivenom has been available since 1956. This makes the redback one of the few spider species that can be seriously harmful to humans.