Red Back Spiders Profile (With Facts and Pictures)

The redback spider has a small body that is pea-shaped and black in color. On the top, it has a red stripe and it is considered one of the most lethal spiders in the world. It ranks on position number 2 as a dangerous spider. The female redback spider is extremely poisonous, on the other hand, the male is not really dangerous. 

Fast Facts: Redback Spider

  • Scientific Name: Latrodectus hasseltii
  • Other Names: Redback spider, red-striped spider, or Australian black widow
  • Lifespan: 2-3 years for the female; 6-7 months (male)
  • Basic Animal Group: Invertebrate
  • Population: Abundant
  • Female Size: 0.4 inches for the female,
  • Male Size: 0.12-0.16 inches 
  • Diet: Carnivore
  • Habitat: Australia, Southeast Asia, and New Zealand,
  • Conservation Status: Not Evaluated

The Profile

The poisonous redback spider, Latrodectus hasseltii, is native to Australia. It belongs to the widow spider genus Latrodectus, which is found all over the world.

The female has a body that measures around 10mm in length. the female also has an hourglass-shaped pattern on the bottom of her body, in addition to the prominent orange or red stripes on top of her body.

The male has a slender, light brown body with comparable but lighter patterns than that of the female, and at 4 mm in length, he is roughly 60% smaller as compared to the female. The male may weigh about 1% of the female.

In comparison to female redback spiders, male redback spiders are rather modest. They are not poisonous to humans, however, they may be venomous during the mating season although this is rare. The redback spider also displays sexual cannibalism during mating. 

The mature female redback has a spherical body and long, thin legs, measuring approximately 1 cm (0.4 in) in length. The body is dark black (often brownish), with a crimson (often orange) longitudinal line running down the abdominal area.

An hourglass-shaped red/orange stripe runs along the bottom of the abdomen. Redback spiderlings are gray with dark markings, and with each molt, they get darker.

The female red stripe follows the same pattern, beginning as a single red spot and then merging into numerous spots. On the thorax of juvenile females, there are extra white markings.

In 45–90 days, male spiders grow through 5 stages. In around 75–120 days, females grow through 7 to 8 instars.

Males may survive for up to 6 months, while females can survive for up to 3 years. Spiders can live for 100 days without food on average, and up to 300 days in extreme cases. Redbacks can withstand temperatures ranging from below zero to 40 degrees Celsius.

The wind carries the baby redback spiders away from their mother’s web. A droplet of silk is produced as the spider stretches its stomach high into the air. The spider is carried away on a lengthy gossamer string made from liquid silk. The silky thread will finally cling to something, and the baby spider will spin its own web.

So because gonads and palp are not directly linked, a young male develops a tiny sperm web prior to actually leaving its mother’s web.

Female redback spiders that have not yet been mated release pheromones, along with a serine derivative, into their web. This is considered to be the only way for males to determine a female’s reproductive state, and their courting destroys most of the pheromone-marked web.

Only two species have been discovered where the male actively assists the female in sexual cannibalism: the redback spider and the black widow spider. A much tiny male does a flip to put his abdomen over the female’s mouthparts during the mating procedure.

In roughly two out of every three matings, the female completely swallows the male. Males that aren’t eaten perish shortly after mating from their injuries. Males are considered to benefit from sacrifices in mating via two factors.

The first is that the feeding process leads to greater copulation time and hence more eggs to be fertilized. The second point is that females that have consumed a male are much more likely to reject other males.

Even though this prevents males from copulating in the long term, this is not a significant disadvantage, this is the case because spiders are so scarce that only 20% of males find a potential partner throughout their entire lives, and in any scenario, the male is structurally sterile if he has been using the contents of either his paired palps during the first mating.

The sperm is kept the females are the sperm storage organ, called the spermathecae after she has mated.

The sperm can also be utilized to lay many batches of eggs in a 2 year period of time, although she usually begins pheromone production 3 months following mating to advertise her sexual availability.

A female spider can lay about 4 to 10 egg sacs, each containing approximately 250 eggs on average, however, this number can range from 40 to 500. She can deposit a fresh egg sac as soon as 1-3 weeks after the last one is laid.

Female Redback Spider Habits

The female spider resides in an unkempt web in a warm, protected place and feeds on bugs, insects, and lizards that it captures, although it may go for more than 100 days without eating. Various spider species, as well as parasitoid wasps, feed on it.

Redbacks mostly eat insects, but they may sometimes catch larger creatures caught in the web, such as king crickets, trapdoor spiders, and tiny lizards.

Food leftovers and illumination lure bug prey to locations where humans are present, bringing their predators with them. Prey stealing is a common occurrence in which bigger females steal food from other spiders’ webs.

When they come into contact with other spiders of the very same kind, frequently such as those of the opposite sex, they fight, and the loser gets eaten. If a female welcomes the male, the male is free to prey on the victims caught in her web.

Male Redback Spider Habitat

The male redback hides during day time, whereas the female spins a web at night, generally in the same spot for the majority of its adult years. The web is a knot of thin yet robust silk that is disorganized and uneven. 

The spider and egg sacs are situated in the back section of the web, which forms a funnel-like escape region. Vertical, adhesive trapping threads run to ground attachments in this location. 

The vertical threads have two functions: they catch prey and tiny insects and maybe hoisted into the air, and they also operate as a tripwire, alerting the spider to the proximity of prey or dangers.

The origins of the redback spider are unknown, however, it is possible that it was transmitted by humans. Only fifteen years after European arrival, the species was discovered in South Australia in 1850, although it was not found in early spider samples in other provinces.

 It has also been argued that the redback is not native to Australia because it was first seen near seaports. In Australia as well as its towns, it may now be seen in all but the most hostile settings. 

Outside of urban areas, the redback prefers drier environments such as sclerophyll woodland and desert, including the harsh Simpson Desert. Redback spiders are frequently seen in close proximity to human dwellings.

Webs are typically constructed amid stones, in wood, tree hollows, bushes, old tyres, sheds, huts, abandoned tins and boxes, kids toys, or beneath garbage or litter. Common locations include mailboxes and the underside of toilet seats.

When prey scramble about, the horizontal threads known as man lines snap. Typically, these webs are sandwiched between two smooth surfaces, one on top of the other. They may sometimes use fallen leaves to create a more enclosed nest, according to rare sightings.

Threats

One of the most deadly spider species is the redback. In Australia, it is widely distributed, and colonies have been formed in a variety of other nations. It prefers to live in close proximity to people and is responsible for the vast majority of Australian spider bites, many of which have significant medical implications. 

Anti-venom is available on the market, and no deaths have been publicly documented as a result of redback bites ever since its debut in 1956.

Latrodectism is a condition caused by redback spider bites, which has similar symptoms to other Latrodectus spider attacks.

Extreme pain is a common symptom of the condition. At the puncture location, a red patch is generally evident. The bite may be unpleasant right away, but it might also feel like a pinprick or a slight burning feeling after a while. 

Within about an hour, patients often experience more acute local discomfort, edema, and piloerection (goosebumps). The location of pain, swelling, and redness might extend proximally. 

Inflamed or painful regional lymph nodes signal systemic envenoming; other symptoms include fatigue, nausea, puking, abdominal or chest discomfort, generalized perspiration, headaches, fever, hypertension, and tremors.

Seizures, comas, pulmonary edema, respiratory failure, and localized skin infection are all rare consequences. At the site of the bite, acute perspiration and stiffness can develop, and lymphatic inflammation could lead to lower limb discomfort.

Prevention

Cleaning habitats, trapping spiders and their egg sacs, and using pesticides in outhouses can all help decrease infestations. Since their toxicity and the fact that redbacks are quick recolonizing, several experts advise against using spider pesticides.

Feeding and diet

Redback Spiders usually eat insects, but if they are caught in the web, they may catch very large creatures including male trapdoor spiders, king crickets, and tiny lizards. Prey theft is also prevalent, with big females snatching stored food from other people’s webs.

Can a Redback Spider Kill You?

The venom of the redback spider may kill a person, although it takes a long time to do it.

The bite of a redback spider is usually not visible right away. Approximately 5–60 minutes just after the bite, the pain begins. The entire leg will be uncomfortable in an hour, and perspiration will begin. Discomfort in the abdomen or chest may occur, as well as pain in other regions of the body.

Because the venom of the redback spider is sluggish, you have more than enough time to seek medical help. Avoid using a constraining bandage since the pressure will just make the discomfort worse.

The only thing that can be done to assist relieve the agony is to apply ice packs to the bitten location and seek medical assistance as quickly as possible.

Life history cycle

After mating, the female may retain sperm and use it to lay many batches of eggs over a two-year period. She spends lots of time making up to ten spherical egg sacs that start off white and become brown over time. 

Each egg sac has about 250 eggs, and it only takes 1-3 weeks for additional eggs to be deposited. Inside the web, these sacs are hung. They are often parasitized by little ichneumonid wasps, which puncture each sac with perforations.

 In 2 to 4 weeks, the tiny spiderlings hatch. Cannibalistic spiderlings will consume unhatched eggs as well as other spiderlings.

On lengthy silk strands caught in wind currents, the spiderlings spread by ballooning to some other appropriate nest location.

Females grow in around 4 months on average. The younger male develops in around 90 days on average. Female spiders may survive for 2 – 3 years, but males only last 6 to 7 months.

Predators and parasitoids

The redback spider is noted to be preyed upon by the black house spider, cellar spider, as well as gigantic daddy-long-legs spider, therefore redbacks are frequently missing when these kinds are widespread in the environment. 

The spider wasp Agenioideus nigricornis is a parasitoid of the adult redback. Redback eggs are parasitized by wasps from the Eurytomidae and Ichneumonidae families, while redback eggs are eaten by mantid lacewings.

Danger to humans

Redback bites are common, especially during the summer months. Every year, antivenom is administered to over 250 instances, with numerous lesser envenomations likely going unnoticed. The female bite is the only one that is harmful. 

They are capable of causing significant sickness and have resulted in fatalities. Yet, since Redback Spiders seldom leave their webs, people are unlikely to be bitten except if a body part, like a hand, is placed directly into the web, and many bites are unsuccessful due to their tiny jaws. The venom works directly on the neurons, causing neurotransmitter release and eventual depletion.

Pain (which could become intense), perspiration (that always includes local sweating at the bite site), muscle pain, nausea, and vomiting are all common early symptoms. There is antivenom present. Since its inception, there have been no deaths.

To alleviate discomfort, apply an ice pack to the injured area. Applying pressure bandages is not recommended. Capture the spider to be sure it’s the right one. Seek medical assistance.

Evolutionary relationships

The Redback Spider, Latrodectus hasselti, was formerly mistakenly considered to have been a subtype of the Black Widow Spider, however, it is now recognized as a separate species.

The Redback is a unique species, perhaps strongly linked to the New Zealand Katipo, and also most likely an Australian native, according to a recent study on DNA sequences of all identified Latrodectus species.

Because European settlers began supplying them with a variety of locations to spin webs, redbacks are believed to have grown even more widespread.

Conclusion

The broad red stripe extending down the back of the female’s stomach distinguishes the redback. Males and females have distinct physical characteristics. Both have eight legs, with a front set being the longest of the fours. 

Spiders that dwell in a web are known as redbacks. There are two components to this. The spider dwells and produces its egg sac in the upper portion.

 It also provides structural support for the lowest section of the web, where their prey is trapped. This region is made up of a series of vertical trip lines that are covered in liquid silk and attach prey to the web.

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