Here are 5 new species of Australian trapdoor spider. It took scientists a century to tell them apart


A female Euoplos variabilis from Mount Tamborine.
Jeremy Wilson

Mark Harvey, The University of Western AustraliaAfter a century of scientific confusion, we can now officially add five new species to Australia’s long list of trapdoor spiders — secretive, burrowing relatives of tarantulas.

It all started in 1918, when a species known as Euoplos variabilis, was first described. Since then, this species has been considered widespread throughout south-eastern Queensland.

However, in new research, fellow arachnologists from the Queensland Museum studied the physical appearance and DNA of these trapdoor spiders. They revealed this “widespread” species is actually several.

Many trapdoor spider species are short-range endemics, meaning they only occur in one small area. This makes them especially vulnerable to threats such as habitat destruction and degradation, which is why the discovery and description of these new species from Queensland is so important — they can now be protected from future threats.

Meet Australia’s trapdoor spiders

To many people, Australia’s spider diversity is a source of fear. To arachnologists like myself, it’s a goldmine.

Weird and wonderful new species are everywhere. While new discoveries are relatively common, it’s likely most Australian spider species are still yet to be named by science.

The crenate burrow of Euoplos crenatus, a recently discovered ‘palisade trapdoor spider’.
Michael Rix

Trapdoor spiders live in burrows that usually have a hinged door at the entrance that the spider constructs using silk, soil or other material from the surrounding area. Their burrows can be camouflaged, but to a trained eye they’re easily found on the soil embankments beside walking tracks in eastern Australian rainforests.

In the past few years, I’ve been part of a team studying the spiny trapdoor spiders — a group of relatively large (up to about seven centimetres long, including legs) but highly secretive spiders found throughout Australia. They belong to an ancient group called the Mygalomorphae that, alongside tarantulas, includes the infamous Australian funnel-web spiders.

Australian spiders of the group called the Mygalomorphae: left, a funnel-web spider; middle, a wishbone spider; right, a tree trapdoor spider.
Jeremy Wilson

Like other trapdoor spiders, adult male and female spiny trapdoor spiders look shockingly different. When males reach adulthood, their physical appearance changes: their legs get longer and thinner, and their first appendages (called “pedipalps”) develop into structures used for mating. In contrast, adult females remain short-legged and robust.

Male trapdoor spiders undergo this dramatic change because as adults they must leave their burrow and search for females to breed.

Their long legs presumably help them run faster and further in search of females, and also allow them to keep the vulnerable parts of their body out of harm’s way once they meet the (usually larger) female, who isn’t always happy to see them.

The mystery of the trapdoor spider from Mount Tamborine

This striking differences in appearance between male and female spiny trapdoor spiders (“sexual dimorphism”) was at the heart of the mystery regarding the true identity of Euoplos variabilis.

A male and female of the same species of trapdoor spider, showing the sleek, long-legged male and the robust female.
Jeremy Wilson

When the species was first described in 1918, it was based only on female spiders, which were red-brown, large and lived in the rainforest of Mount Tamborine, just south of Brisbane.

In 1985, a male spider, also from Mount Tamborine, was finally linked to the original females. Matching male and female trapdoor spiders of the same species can be difficult because they look so different.

This all changed when the Queensland Museum team began researching the spiny trapdoor spiders of eastern Australia in 2015. When they looked in the museum’s natural history collection, it seemed like males of the Mount Tamborine trapdoor spider were widespread, spanning Brisbane to the Sunshine Coast.




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But strangely, they found females from different locations looked different.

While females from the Mount Tamborine rainforest were large and red-brown, those from the lowlands of north Brisbane were small and tan. And in the rainforest of the D’Aguilar Range, north of Brisbane, the females were even bigger, with a bright orange carapace and red legs.

Could these really all be the same species?

One of the males originally thought to be Euoplos variabilis. It was later realised these males belong to an entirely different species, now called Cryptoforis hughesae.
Michael Rix

This mystery was solved in two steps

First, in 2018, the museum’s arachnologists discovered the seemingly widespread males were actually members of a completely different group of trapdoor spiders, which also occurs in eastern Australia. In other words, there had been a male/female mismatch!

Then, by collecting fresh trapdoor spiders around south-east Queensland and studying their DNA, they discovered the Mount Tamborine trapdoor spider actually doesn’t occur in Brisbane at all. In fact, it’s found only in the mountain ranges bordering New South Wales, with Mount Tamborine being its the most northerly location.

Surprisingly, the female spiders found in Brisbane, the D’Aguilar range, and in various other areas, turned out to be several completely different species, new to science.




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These species can be distinguished by subtle differences in size and colour, and by differences in their DNA. The different species seem to be adapted to different habitats, at different elevations.

So, alongside Euoplos variabilis, the original Mount Tamborine trapdoor spider, the new confirmed species are:

  • Euoplos raveni and Euoplos schmidti, both from the lowland forests of the Brisbane Valley, south of the Brisbane River
  • Euoplos regalis from the upland rainforest of the D’Aguilar Range
  • Euoplos jayneae from the the lowland forests of the Sunshine Coast hinterlands
  • Euoplos booloumba from the upland rainforest of the Conondales Range

These five new species put the total number of known spiny trapdoor spider species to 258.

Don’t be alarmed, bites from a trapdoor spider aren’t dangerous to humans.
Shutterstock

What happens now?

And so, the mystery was solved. Another small fraction of Australia’s beautiful biodiversity is known to science and can be preserved. But the story isn’t over just yet.

To properly conserve these species, we need to understand more about how they live. This is why the research team and I are undertaking a long-term study on one of these new species, Euoplos grandis from the Darling Downs. We hope to learn the intricacies of their lives and to track whether populations are declining from threats such as habitat destruction.




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We’re also continuing our mission to discover and describe new species of trapdoor spider, not just from Queensland, but from all around Australia.

The story of the Mount Tamborine trapdoor spider exemplifies the type of detective work Australian scientists undertake on all types of animal groups. But when it comes to invertebrates, we’ve barely scratched the surface, with new species of bugs, spiders, worms and more waiting to be discovered.

Working on discovering these invertebrates comes with a sense of urgency. These species need a name and formal protection, before it’s too late.

Who would win in a fight between a scorpion and a tarantula? A venom scientists explains for The Conversation.

Jeremy Wilson and Michael Rix from Queensland Museum were co-authors on this articleThe Conversation

Mark Harvey, Curator of Arachnology at the Western Australian Museum, Adjunct Professor, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Spiders are cloaking Gippsland with stunning webs after the floods. An expert explains why


Darren Carney

Lizzy Lowe, Macquarie UniversityStunning photographs of vast, ghostly spider webs blanketing the flood-affected region of Gippsland in Victoria have gone viral online, prompting many to muse on the wonder of nature.

But what’s going on here? Why do spiders do this after floods and does it happen everywhere?

The answer is: these webs have nothing to do with spiders trying to catch food. Spiders often use silk to move around and in this case are using long strands of web to escape from waterlogged soil.

This may seem unusual, but these are just native animals doing their thing. It’s crucial you don’t get out the insecticide and spray them. These spiders do important work managing pests, so by killing them off you would be increasing the risk that pests such as cockroaches and mosquitoes will get out of control.




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Using silk to move around

What you’re seeing online, or in person if you live locally, is an amazing natural phenomena but it’s not really very complicated.

We are constantly surrounded by spiders, but we don’t usually see them. They are hiding in the leaf litter and in the soil.

Spider webs blanket the ground in Gippsland
When floods happen, spiders use silk to evacuate quickly.
Darren Carney

When these flood events happen, they need evacuate quickly up out of holes they live in underground. They come out en masse and use their silk to help them do that.

You’ll often see juvenile spiders let out a long strand of silk which is caught by the wind and lifted up. The web catches onto another object such as a tree and allows the spider to climb up.

That’s how baby spiders (spiderlings!) disperse when they emerge from their egg sacs — it’s called ballooning. They have to disperse as quickly as possible because they are highly cannibalistic so they need to move away from each other swiftly and find their own sites to hunt or build their webs.

Small spiders have been seen on a post in Gippsland after floods.
AAP Image/JEFF HOBBS

That said, I doubt these webs are from baby spiders. It is more likely to be a huge number of adult spiders, of all different types, sizes and species. They’re all just trying to escape the flood waters. These are definitely spiders you don’t usually see above ground so they are out of their comfort zone, too.

This mass evacuation of spiders, and associated blankets of silk, is not a localised thing. It is seen in other parts of Australia and around the world after flooding.

It just goes to show how versatile spider silk can be. It’s not just used for catching food, it’s also used for locomotion and is even used by some spiders to lay a trail so they don’t get lost.

Don’t spray them!

The most important thing I need readers to know is that this is not anything to be worried about. The worst thing you could do is get out the insecticide and spray them.

These spiders are making a huge contribution to pest control and you would have major pest problems if you get rid of all the spiders. The spiders will disperse on their own very quickly. In general, spiders don’t like being in close proximity to each other (or humans!) and they want to get back to their homes underground.

If you live in Gippsland, you probably don’t even need to clear the webs away with a broom. There’s no danger in doing so if you wish, but I am almost certain these webs will disperse on their own within days.

Until then, enjoy this natural spectacle. I wish I could come down to see them with my own eyes!




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The Conversation


Lizzy Lowe, Researcher, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

It’s getting hotter, so spiders are emerging. Should I be alarmed?



Golden orbweaver spiders may appear in your gardens.
Samantha Nixon, Author provided

Lizzy Lowe, Macquarie University and Samantha Nixon, The University of Queensland

In spring and summer every year, stories about “hordes of spiders” and “flesh-eating venom” fill tabloids and social media.

This rhetoric greatly exaggerates the relative risk of Australian spiders, leading to excessive pesticide use and unnecessary phobias.

There are more than 49,000 species of spiders in the world and around 4,000 of these live in Australia, many with astounding behaviours, beautiful colours and natural, biological pest control potential. We should be celebrating the diversity of our spiders in Australia — and what better time than right now?

Many insects and spiders have been growing over the winter months to emerge once the weather gets warmer. This means you’re probably going to start noticing more spiders around your house and garden. So which ones should you worry about?

St Andrews cross spider on its unique web
St Andrews cross spiders build beautiful, unique webs, and the spider sits with its legs in pairs.
Shutterstock

Don’t fear these common household spiders

Some spiders like to live in houses. It’s cool, dry and there are hundreds of tasty insects to eat that you may not have even noticed, such as silverfish, book lice and springtails.

One of the most common spiders people find at home across Australia is, true to its name, the black house spider. These spiders build messy webs on fences and in the corners of windows.

Because they’re black, people can mistake these spiders for funnel-webs, but black house spiders are smaller and harmless. Also, a funnel-web will never make a web in your window.




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In your garden you may spot webs with a white cross (from St Andrews cross spiders, Argiope keyserlingi), with leaf retreats (from leaf curling spiders, Phonognatha graeffei), or golden silk (from golden orb weaving spiders, Trichonephila sp.). While impressive, these spiders are shy and their venom is harmless.

Even larger are huntsman spiders (from the Sparassidae family). While they’re famously fast moving, their bites are rare and, at worst, cause mild to moderate pain.

The good news is the vast majority of Australian spiders are harmless. In fact, a global study found less than 0.5% of spiders are dangerous to humans.

However, Australia is home to a number of “medically significant” spiders whose bites can be severe.

Huntsman spider on a tree
Huntsmans are huge, but generally harmless.
Shutterstock

Funnel-webs are emerging from their burrows

First and foremost are funnel-web spiders, which are in the Atracidae family. Sydneysiders are likely well aware of the infamous Sydney funnel-web spider (Atrax robustus), but there are actually around 40 species of funnel-web spiders spread up and down the east coast of Australia.

Most funnel-webs will spend their lives hidden in their burrow. But during spring and summer, male spiders will wander about the bush (and sometimes back gardens) looking for mates, increasing the risk of human contact.




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Recent studies into funnel-web venom evolution have shown male Sydney funnel-webs have a high concentration of a toxin called “delta-hexatoxin”, which disrupts neuronal signalling and can lead to respiratory and cardiac failure. This helps them catch insect prey and defend themselves by causing pain in predators.

But through a quirk of evolution, this toxin can be fatal to humans.

The hexatoxins are distributed throughout the funnel-web family. To date, serious bites have only been reported from funnel-webs in southern Queensland and NSW. This includes the Sydney, Blue Mountains, Toowoomba/Darling Downs and the Northern Tree-dwelling funnel-web spiders.

Sydney funnel-web raising its legs
Funnel-web spiders spend most their lives hidden in a burrow.
Shutterstock

Mouse spiders and redbacks

Mouse spiders (Missulena sp.) also have a toxin similar to hexatoxin in their venom, so their bites have similar effects. Like the funnel-webs, there are species of mouse spiders all over Australia.

Fortunately, clinical studies suggest serious mouse spider bites are rare, but these spiders should still be treated with caution.

Mouse spider crawling on a rock
Mouse spiders are best avoided.
Shutterstock

And then there’s the renowned Australian redback spider (Latrodectus hasselti), with its striking red stripe. These spiders are found across the continent.

Redback spiders are related to American black widows and have toxins called latrotoxins, which also disrupt neuronal signalling in their prey. (It’s the female redbacks you need to keep an eye out for.)

Redbacks have a painful bite and symptoms can persist for several days. Fortunately for both redbacks and funnel-webs, effective antivenom treatments are available. If bitten, it’s always best to seek medical attention.

It’s worth noting no one has died directly from a spider bite in Australia in more than 40 years since the introduction of antivenom. So while Australian spiders may have a fearsome reputation, it’s somewhat overblown.

The infamous redback spider (Latrodectus hasselti) is one of Australia’s few spiders capable of serious envenomation.
Sam Robinson, Author provided

What to do with spiders in your house and garden

The first thing you should ask yourself is, do I need to get rid of them at all?

Spiders play an important role in the control of pests such as cockroaches and mosquitoes, so much so that each year, spiders eat more insect biomass than the weight of the entire human population.

A black house spider against a wall
Black house spiders build messy webs.
Shutterstock

If you come face to face with an unwanted spider in your house, we recommend using a container and piece of paper for a simple catch-and-release into the garden. If the webs are what bothers you — and we’ve all walked face-first through a web at some point — sweeping them away will usually be enough for the spider to move on.

Alternatively, you can leave the webs in the garden to catch other insects (think of them as functional, miniature artworks).

Redbacks have a habit of building their webs under, for example, the rims of pot plants and in outdoor furniture. This can be a problem, especially for small children.




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So keeping your house and garden tidy, regularly sweeping and avoiding leaving junk lying around makes your garden less attractive for web-building.

It’s also good to avoid leaving shoes outside (or shaking them out) and checking your swimming pools for lost wandering spiders. This will help prevent accidental contact with funnel-webs during spring and summer.

Using amazing close-up footage, Sir David Attenborough explores the world of the redback spider.

If you really have to kill a redback, a quick squish with the shoe is far better than using pesticides, which have negative impacts on human health and the environment. This includes polluting streams, harming birds and bees, and leading to insecticide resistance in pests such as cockroaches and mosquitoes.

Spiders are a key part of Australia’s native ecosystems, including in cities. The harm we do to our own health and the environment by using excessive pesticides far outweighs the risk spiders pose to us.

If we can learn to live alongside these not-so-creepy crawlies, our houses and gardens will be better for it.




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The Conversation


Lizzy Lowe, Postdoctoral researcher, Macquarie University and Samantha Nixon, PhD, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Don’t like spiders? Here are 10 reasons to change your mind



Hostile reactions to spiders are harming conservation efforts.
Karim Rezk/Flickr

Leanda Denise Mason, Curtin University

Australia is famous for its supposedly scary spiders. While the sight of a spider may cause some people to shudder, they are a vital part of nature. Hostile reactions are harming conservation efforts – especially when people kill spiders unnecessarily.

Populations of many invertebrate species, including certain spiders, are highly vulnerable. Some species have become extinct due to habitat loss and degradation.




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In dramatic efforts to avoid or kill a spider, people have reportedly crashed their cars, set a house on fire, and even caused such a commotion that police showed up.

A pathological fear of spiders, known as arachnophobia, is of course, a legitimate condition. But in reality, we have little to fear. Read on to find out why you should love, not loathe, our eight-legged arachnid friends.

A male peacock spider. Spiders are a vital part of nature.
She’s Got Legs/Caitlin Henderson

1. Spiders haven’t killed anyone in Australia for 40 years

The last confirmed fatal spider bite in Australia occurred in 1979.

Only a few species have venom that can kill humans: some mouse spiders (Missulena species), Sydney Funnel-webs (Atrax species) and some of their close relatives. Antivenom for redbacks (Latrodectus hasseltii) was introduced in 1956, and for funnel-webs in 1980. However, redback venom is no longer considered life-threatening.

2. Spiders save us from the world’s deadliest animal

Spiders mostly eat insects, which helps control their populations. Their webs – especially big, intricate ones like our orb weavers’ – are particularly adept at catching small flying insects such as mosquitos. Worldwide, mosquito-borne viruses kill more humans than any other animal.

3. They can live to an impressive age

The world’s oldest recorded spider was a 43- year-old female trapdoor spider (Gaius villosus) that lived near Perth, Western Australia. Tragically a wasp sting, not old age, killed her.

4. Spider silk is amazing

Spider silk is the strongest, most flexible natural biomaterial known to man. It has historically been used to make bandages, and UK researchers have worked out how to load silk bandages with antibiotics. Webs of the golden orb spider, common throughout Australia, are strong enough to catch bats and birds, and a cloak was once woven entirely from their silk.

Golden orb weaver (Trichonephila edulis)
Caitlin Henderson/She’s Got Legs

5. Their venom could save our life

The University of Queensland is using spider venom to develop non-addictive pain-killers. The venom rapidly immobilises prey by targeting its nervous system – an ability that can act as a painkiller in humans.




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The venom from a Fraser Island funnel web contains a molecule that delays the effects of stroke on the brain. Researchers are investigating whether it could be administered by paramedics to protect a stroke victim on the way to hospital.

Funnel-web venom is also being used to create targeted pesticides which are harmless to birds and mammals.

6. They could compete at Little Athletics

The Australian huntsman (Family Sparassidae) can run 40 body lengths per second, about eight times faster than the fastest human runners.

Other spiders have great throwing skills. To catch moths, the bolas spider spins a thread with a sticky glob of silk on the end. The glob mimics the scent of a female moth. When a male moth comes to investigate, the spider throws the glob at the moth, catches it then reels it in.

7. Spiders want to be left alone

Spiders are not aggressive and will either try to run away from people, or defend themselves. Many are exceptional at hiding or camouflaging themselves, in the hope we don’t even see them.

Wrap-around spiders (Dolophones species) flatten themselves around branches to hide during the day, then come out to build webs at night.

A wrap-around spider (Dolophones species) is a master of camouflage.
Caitlin Henderson/She’s Got Legs

Bird-dropping spiders hide by looking like, yes, bird-droppings.

The Western Australian shield-back trapdoor spiders (Idiosoma species) uses its unusually hard abdomen to “plug” its tunnel when a predator enters, creating an impenetrable shield.

Trapdoor spiders live in burrows with a silken lid that shuts tight, then gets covered in dirt or leaf litter.

Trapdoor burrows of an Idiosoma species open (left) and closed (right)
Author provided

8. Spiders have very unusual sex lives

It’s well known that some female spiders eat their partners during or after sex. But male Tasmanian cave spiders have evolved to avoid this fate. They use kinks in their legs to pin the female’s fangs apart while they mate, which can prevent her from killing him. These spiders are so fascinating, they are the subject of a documentary, Sixteen Legs

More generally, male spiders use their “hands” (called pedipalps), to transfer sperm into female spider “vaginas” (called epigynes).

During courtship, Australian male peacock spiders display their colourful abdomen to the female by using some pretty impressive dance moves.

9. Spiders are great mothers

Some female spiders produce milk for their young, or even sacrifice themselves as food. All spider mothers protect their babies, called spiderlings. However trapdoor spider mothers allow spiderlings to live in the home burrow for nine months, before they dig their own burrows nearby.

A wolf spider carrying her spiderlings.
She’s Got Legs/Caitlin Henderson

10. Humans need spiders to survive

It is important to remember that spiders and other invertebrates – animals without spines – make up 98% of animal species. They are vital to the functioning of ecosystems; without them, the remaining 2% of vertebrates, including humans, could not survive.

OK, OK. I care about spiders. Now what?

Spread the word to your friends and family that spiders should be cared for.

By all means, teach children that certain spiders require caution, and should be admired from a safe distance. But if your child has an irrational fear of spiders, address this as early as possible. Encourage positive interest in the spider world by exposing children to books and movies with spiders as the lead protagonists, such as Charlotte’s Web and Spiderman.

Research has shown that adults can overcome fear of spiders through frequent exposure. So be sure to share images of spiders with your arachnaphobic friends!

Caitlin Henderson contributed to this article.




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The Conversation


Leanda Denise Mason, Associate Lecturer, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids: why do spiders need so many eyes but we only need two?



Jumping spiders, like this one, usually have eight eyes: two very large front eyes to get a clear, colour image and judge distance, and extra side eyes to detect when something is moving.
Flickr/Thomas Shahan, CC BY-NC-ND

Samantha Nixon, The University of Queensland and Andrew Walker, The University of Queensland

Curious Kids is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.


Can you find out why spiders need six eyes but we only need two? – Amos, age 3, Newcastle.


Hi, Amos. Thanks for your excellent question.

The first thing we should say is that while it’s true that some spiders have six eyes, most actually have eight.

The short answer to your question is that animals have evolved different eyes that best suit the lives they lead.




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Humans have two eyes that face forward. Our eyes are very good at seeing colours and shapes. Having two big eyes in the front of our head means they can work together to guess how far away something is (we call this “judging distance”). That makes it easier for us to catch another animal so we can eat it.

Spiders are also hunters and they need eyes that help them find and catch their food. In fact, most spiders can’t see very well, and use touch and taste to explore the world. But the kind of eyes they have tells us something about the food they eat and the lives they live.

Spider eyes for spider lives

Jumping spiders are active hunters, like tiny lions chasing down their prey (bugs). They usually have eight eyes: two very large front eyes to get a clear, colour image and judge distance, and extra side eyes to detect when something is moving. Here’s a picture of an Australian jumping spider.

Jumping spiders need two big eyes on the front so they can guess how far away their prey is.
Michael Duncan., Author provided

Some spiders make nets to catch their prey. These net-casting spiders also need to see clearly and judge distances. Some have developed huge, scary-looking black eyes that stare straight ahead, so they are nicknamed ogre spiders! These gigantic eyes help the spider to see a wide area and accurately throw down its spider web net to catch its prey. Here’s a picture of a net-casting spider.

This net-casting spider is from the Deinopis family. The little dots that look like nostrils are actually eyes!
Michael Duncan, Author provided

Some spiders live in caves that are completely dark, where eyes are no use at all. They have to rely on other senses to find their food in the dark. To save energy making eyes, these spiders lost their eyes during evolution, so now some of them have no eyes at all. You can see a picture of a spider like that here.

So why did most spiders end up with so many eyes?

Both human and spider eyes are the result of slowly evolving to help us survive in our different environments. One reason our human eyes are different from spiders is because our bodies and brains are also built differently.

For example, spiders don’t have necks. So they can’t turn their heads to look at things like we can. Having extra eyes around their heads is one way that spiders see more of the world around them, helping them to quickly spot prey or a potential predator.

Human eyes and spider eyes also do different jobs. Our two eyes are very complex and are good at doing many jobs at once, while spiders have different sorts of eyes that do different jobs.

For example, the large central eyes of jumping spiders are best for seeing shapes, but the simple side eyes have the important job of watching out for predators.

So a two-eyed spider or even an eight-eyed human isn’t impossible. But the two eyes we have and the eight eyes most spiders have are perfectly suited to help each of us live our lives just the way they are.




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Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au


CC BY-ND

Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.The Conversation

Samantha Nixon, PhD, The University of Queensland and Andrew Walker, Postdoctoral Research Fellow, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change is killing off Earth’s little creatures



File 20190116 152983 bx2j9j.jpg?ixlib=rb 1.1
A jumping spider, which uses sharp eyesight to hunt its prey.
ThomasShahan.com/Flickr, CC BY-SA

Bill Laurance, James Cook University

Climate change gets blamed for a lot of things these days: inundating small islands, fueling catastrophic fires, amping-up hurricanes and smashing Arctic sea ice.

But a global review of insect research has found another casualty: 40% of insect species are declining and a third are endangered. It confirms what many have been suspecting: in Australia and around the world, arthropods – which include insects, spiders, centipedes and the like — appear to be in trouble.




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The global review comes hard on the heels of research published in the Proceedings of the National Academy of Sciences USA that suggests a potent link between intensifying heat waves and stunning declines in the abundance of arthropods.

If that study’s findings are broadly valid – something still far from certain – it has chilling implications for global biodiversity.

Our natural world depends on arthropods.
Steve Raubenstine/Pixabay

Arthropod Armageddon

In the mid-1970s, researchers on the Caribbean island of Puerto Rico conducted a large-scale study to measure the total biomass (living mass) of insects and other arthropods in the island’s intact rainforests, using sweep nets and sticky-traps.

Four decades later, another research team returned to the island and repeated the study using identical methods and the same locations. To their surprise, they found that arthropod biomass was just one-eighth to one-sixtieth of that in the 1970s – a shocking collapse overall.

And the carnage didn’t end there. The team found that a bevy of arthropod-eating lizards, birds and frogs had fallen sharply in abundance as well.

Insects are crucial in food webs for species such as this hummingbird.
Pixabay

In the minds of many ecologists, a widespread collapse of arthropods could be downright apocalyptic. Arthropods pollinate some of our most important food crops and thousands of wild plant species, disperse seeds, recycle nutrients and form key links in food chains that sustain entire webs of life.

This ecological ubiquity arises because arthropods are so abundant and diverse, comprising at least two-thirds of all known species on Earth. In the 1940s, evolutionary biologist J. B. S. Haldane quipped that “God has an inordinate fondness for beetles.” Humans might think we rule the world, but the planet really belongs to arthropods.

Killer heat waves

The researchers who documented the arthropod collapse in Puerto Rico considered a variety of possible causes, including pesticides and habitat disruption. But the evidence kept pointing to another driver: rising temperatures.

Weather stations in Puerto Rico indicate that temperatures there have risen progressively in the past several decades – by 2℃ on average.

But the researchers are far less worried about a gradual increase in temperature than the intensification of heat waves—which have risen markedly in Puerto Rico. This is because nearly all living species have thresholds of temperature tolerance.

For example, research in Australia has shown that at 41℃, flying foxes become badly heat-stressed, struggling to find shade and flapping their wings desperately to stay cool.

But nudge the thermometer up just one more degree, to 42℃, and the bats suddenly die.

In November, heat waves that peaked above 42℃ in north Queensland killed off almost a third of the region’s Spectacled Flying Foxes. The ground beneath bat colonies was littered with tens of thousands of dead animals. Dedicated animal carers could only save a small fraction of the dying bats.

Bats die en-masse during a recent heatwave.

The El Niño connection

El Niño events – fluctuations in Pacific sea-surface temperatures that drive multi-year variations in weather across large swaths of the planet – are also part of this story. New research appears to be resolving longstanding uncertainties about El Niños and global warming.

Recent studies published in Nature and Geophysical Research Letters suggest global warming will in fact intensify El Niños – causing affected areas to suffer even more intensively from droughts and heat waves.

And this ties back to Puerto Rico, because the researchers there believe a series of unusually intense El Niño heatwaves were the cause the arthropod Armageddon. If they’re right then global warming was the gun, but El Niño pulled the trigger.

Beyond heat waves

Puerto Rico is certainly not the only place on Earth that has suffered severe declines in arthropods. Robust studies in Europe, North America, Australia and other locales have revealed big arthropod declines as well.

And while climatic factors have contributed to some of these declines, it’s clear that many other environmental changes, such as habitat disruption, pesticides, introduced pathogens and light pollution, are also taking heavy tolls.

Monarch butterflies are declining in the USA and Mexico, probably from habitat disruption.
Pixabay

So, at a planetary scale, arthropods are suffering from a wide variety of environmental insults. There’s no single reason why their populations are collapsing.




Read more:
Climate change: effect on sperm could hold key to species extinction


The bottom line is: we’re changing our world in many different ways at once. And the myriad little creatures that play so many critical roles in the fabric of life are struggling to survive the onslaught.The Conversation

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The truth about spider bites in Australia – they’re unlikely to eat your flesh


Ronelle Welton, University of Melbourne and Bill Nimorakiotakis, Epworth Hospital

Recent news reports that a man had both his legs amputated after being bitten by a white-tailed spider have again cast this relatively harmless spider in a negative light. Experts have since said amputations may have been wrongly blamed on a spider bite, and authorities now consider a bacterial infection to be responsible for the man’s injuries. Despite this, the damage to the largely harmless white-tail may have been done. The Conversation

The venom from the white-tailed spider is listed as non-lethal.
It has not been shown to cause necrotic ulcers, which could result in the need for amputation. And there has never been any clear evidence necrotising arachnidism – the name give to a syndrome where the skin blisters and ulcerates following spider bites – has been seen in Australia.

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There is currently no clinical test to determine if you have been bitten by a spider. And there is no blood or swab test that can be performed to positively identify what spider it is if a bite is suspected. Whether it is a bite from a spider or another insect, the management is the same – most will get better without any medical treatment.

Spiders in Australia

The majority of spiders in Australia are voracious predators of insects. For the most part, they play a useful role in lowering insect numbers.

The venom transmitted through bites of some Australian spiders can cause harm to humans and even be life-threatening. The better known of these are the redback spider (Latrodectus hasselti), and the funnel-web spiders (genera Atrax and Hadronyche). Antivenom is available for both spiders.

Redback spider venom can cause a lot of pain. Advice would be to go to hospital if pain lasts for longer than a few hours and simple pain relief is not helping. Funnel-web spider venom can cause local swelling in addition to increasing heartbeat, salivation, muscle spasms and respiratory distress (trouble breathing).

Without appropriate first aid, quick access to hospital and antivenom, these bites can be lethal. For the “big black hairy” funnel-webs, appropriate first aid needs to be applied and it is advisable to call 000.

The redback spider is considered one of the most venomous to humans in Australia.
graibeard/Flickr, CC BY

Other spiders that have concerning bites include the trapdoor, whistling, sac, ground, orb and huntsman spiders. These may cause milder symptoms such as headache, swelling and pain, which does not last for a long time.

The white-tailed spider

White-tailed spiders (Lampona sp.) can be recognised by their cylindrical body shape and a white or grey spot on the end of their abdomen. They are found in eastern and most southern areas of Australia and New Zealand.

These spiders are active hunters, preying on other types of spiders and insects. They may transiently roam inside houses, especially in warmer weather, where they may be found in bedding or clothing that has been left on the floor.

One study of over 70 spider bite cases in which white-tailed spiders were identified showed patients experienced only a mild localised reaction, such as swelling, local pain or headache. To date clinical research has not been able to associate tissue loss with the venom of these spider bites.

Flesh-eating bacteria

The man at the centre of the recent story linking amputations to a white-tail spider bite was said to have a “flesh eating” infection. But there is a very low probability of an association between spiders and necrotisisng fasciitis (commonly known as flesh-eating disease).

Of course, any injury that causes a break in our skin leaves the capacity for bacteria to enter our body. Therefore be sure to keep an injury area clean. Questions have been raised as to the possibility of a spider introducing infections, but again, despite it being theoretically possible, it is unlikely.

Contributing factors to infection are if people have conditions such as diabetes or take medications, such as steroids like prednisolone, that lessen the body’s ability to fight infection.

How to prevent spider bite

  • Leave them alone
  • wear gloves if gardening
  • humanely remove spiders from your home and limit hiding spaces where possible inside the home
  • knock out shoes before putting them on; these are nice quiet homes for spiders.

For first aid after a spider bite, please see the Australian guidelines. Many bites don’t result in envenoming and death is very rare, so it is important to remain calm. But seek medical attention if there are concerning symptoms such as those described above: difficulty breathing, increased heartbeat and pain lasting longer than an hour.

Ronelle Welton, Scientist AVRU, University of Melbourne and Bill Nimorakiotakis, Associate Professor, Epworth Hospital

This article was originally published on The Conversation. Read the original article.

Spiders are a treasure trove of scientific wonder


Maggie Hardy, The University of Queensland

Australia has an incredible diversity of native spiders, including the potentially lethal funnel-web, the ubiquitous huntsman, and the charming peacock spider. Only two can be deadly for humans – the funnel-web and redback spiders – and we have antivenom for both.

Found all across the country, spiders play an important role in the environment as generalist predators. Increasingly, their venom is being used to develop novel human therapeutics and to create new, selective, sustainable insecticides.

A model citizen

How house spider webs change when the spider is exposed to different chemicals.

Spiders are often a starting point for children to fall in love with the natural world: they’re found almost everywhere, and everyone can appreciate their tremendous diversity. What’s more, scientists are constantly learning new things from them.

They’re an important model system to help us understand the basics of biology. We know that the spider and its web are so closely tied that exposure to different chemicals has specific effects on how the webs are spun.

Other research suggests the blue colour in tarantulas evolved independently at least eight times. This may help inform our understanding of the evolution of colouration, as well as how to make better paints.

The peacock spider has helped show that strong sexual selection by females depends on a variety of factors. Scientists think sexual selection has had an impact on the striking coloration and complex signalling of this spider species, but this is the first evidence to definitively demonstrate female preference has played a role.

Dance, dance revolution

With great power…

As a generalist predator, spiders help limit the number of insects in your garden. Although they’ll probably eat some good bugs as well as bad while they’re at it.

Spider venom is a complex chemical cocktail of hundreds of different components, and each type has its own very specific activity. Many individual venom components act on the insect nervous system and these can be very useful for scientific research.

My work, for instance, is on discovering newenvironmentally friendly insecticides from spider venoms. Since insect nervous systems are very different from the one found in vertebrates (including humans), individual toxins are frequently active in insects but not in vertebrates, and vice versa.

The Chemistry of Spider Venom
Compound Interest, CC BY-NC-ND

When we look for good insecticidal candidates we screen for compounds with specific activity in insects and the absence of activity in vertebrates. It’s that specificity that makes spider venoms such powerful sources of new, sustainable insecticides, as well as excellent therapeutics.

What’s in a venom?

Spider venoms generally consist of three types of components: small components (salts, carbohydrates, amines and acids to name a few); peptides (small proteins that are generally highly structured); and enzymes (used for digesting food).

If you get bitten by a spider, do your best to remain calm, and proceed directly to a medical professional so your symptoms can be monitored and treated. They will administer the appropriate antivenom if required.


The Conversation

Spiders deliver venom by injection, using mouth parts called chelicerae, which are informally known as fangs. The chelicerae are found on the front body segment, the cephalothorax, and that’s also where its eight legs are attached.

The abdomen is the other spider body segment, and that’s where the spinnerets, used to weave the web, are found.

Spiders sometimes appear hairy, but those are actually sensory setae that are used to collect detailed information about the nearby environment. Depending on the spider species that could include temperature, humidity, and wind direction, and chemical information, such as the source of pheromones used in mating.

So leave your fear behind and go ahead, embrace the majesty of spiders. But pick your species carefully – and try not to get the police involved.

This article is part of our series Deadly Australia. Stay tuned for more pieces on the topic in the coming days.

The Conversation

Maggie Hardy, Postdoctoral Research Fellow, The University of Queensland

This article was originally published on The Conversation. Read the original article.