8 deadliest spiders on Earth

 

Story by Christina Hughes

Spiders are some of the most successful arthropods on the planet, having colonized every continent except Antarctica. 

Not all of these eight-legged arachnids are venomous, but some can be deadly to humans. 

From the notorious black widow to the ultra-deadly funnel web spider, here are some of the deadliest spiders on Earth.

Brown widow spider©Vinícius Souza via Alamy Stock Photo

Latrodectus geometricus is the scientific name for the brown widow spider. It looks similar to its infamous "cousin" the black widow, right down to the hourglass-shaped marking on its abdomen, but there are some key differences. The brown widow’s marking is orange and yellow rather than red, and as their name suggests, they predominantly have tan and brown mottling and a spiky, rather than smooth, appearance. Believed to originate in South America, the brown widow spider is found all around the world.

The brown widow's venom is less toxic than that of its black cousin. However, it can still be deadly. Although they don't deliver as much venom as a black widow, the brown widow's bite can still cause latrodectism due to its neurotoxic venom. Symptoms of lactrodectism include pain, perspiration, muscle rigidity and vomiting.

Red widow spider©Premaphotos via Alamy Stock Photo

Living mostly in sand dunes in Central and Southern Florida, the red widow spider (Latrodectus bishop) is another member of the notorious "widow" family. Their venom is just as lethal as brown and black widows, but as they live so far from human contact there has been no recorded bite in medical literature. The female red widow spider's venom is a neurotoxin which is thought to cause prolonged muscle spasms.

The red widow spider has a red-orange head and legs and a black abdomen with yellow rings around red dots. Rather than an hourglass marking like its "cousins," the red widow usually has one or two red marks.

Redback spider©By Toby Hudson - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18357323

Due to its strikingly similar appearance, the redback spider (Latrodectus hasselti) was once thought to be a sub species of the black widow spider, but it is a distinct species. Also known as the Australian black widow, you can find this creepy crawly throughout Australia, Southeast Asia and New Zealand. The redback spider has even been found in Japan, the United Arab Emirates and Belgium due to inadvertent introductions.

Highly venomous, the bite from the female redback spider can be life-threatening. Using its fangs, it injects a complex venom that causes intense pain at the bite area, in addition to sweating and goosebumps. As time goes on, these symptoms worsen and there may also be redness and swelling, as well as nausea, muscle twitching, headache and fever. Respiratory failure may occur in severe cases. Thankfully, in 1956 scientists released a redback spider antivenom which is very effective, even when used several weeks after the initial bite. No deaths have been reported since.

Funnel-web spiders©Australian Reptile Park

Normally in the world of spiders it is the female that is more deadly, but for funnel-web spiders (Atrax) the male has the more toxic bite. Any attack must be treated quickly with antivenom, especially if a child has been bitten. There have been several recorded fatalities due to the venomous bites of the funnel-web spider, with death occurring within the hour after being bitten. However, since the development of the antivenom in 1981, there haven’t been any more recorded deaths. Predominantly located in southeast Australia (Sydney), funnel-web spiders are also found in New Zealand, Chile and Europe.

Interestingly, animals such as cats and dogs can actually survive a funnel web bite – it takes about 30 minutes for their body to neutralize the toxin – it's just humans who have such a severe reaction. This venom effects the nervous system and causes symptoms such as an elevated heart rate, numbness/tingling of the mouth and difficulty breathing.

Six-eyed sand spider©Papilio via Alamy Stock Photo

Found in deserts in southern Africa, the six-eyed sand spider (Hexophthalma hahni) buries itself in the sand to ambush unsuspecting prey. The small, stiff hairs that cover the spider helps to hold sand particles in place, adding to its camouflage. It's otherwise known as the six-eyed crab spider due to its crab-like legs.

Another arachnid that produces venom with necrotic effects, the six-eyed sand spider is the most venomous of any of its arachnid relatives, toxicology studies reveal. Scientists have found that there are proteins within their venom that can cause tissue destruction, blood vessel leakage, and thinning of the blood. No antivenom currently exists.

Mouse spider©Peripitus, CC BY-SA 3.0 , via Wikimedia Commons

Black in color with stocky, thick legs and a distinctively bulbous head and jaw regions, the mouse spider (Missulena) looks a lot more frightening than its name sounds. One species is located in Chile, another in South America and the rest distributed throughout Australia. They live in soil-covered burrows, popping out the hinged trapdoor top to attack prey.

Their hard, large fangs can cause a deep and very painful bite. However, while scientists believe that the venom of the mouse spider is very toxic, it is rarely injected. As so few cases have been reported, it is thought that mouse spiders don't use a lot of venom or may even "dry bite." Fortunately, funnel-web spider antivenom has proven effective in cases of mouse spider bite.

Black widow spider©Kimberly Hosey/Getty Images

In the genus Latrodectus, the black widow is one of the most venomous spiders and is found on every continent except Antarctica. In North America, they're commonly found in southern Canada and in the northeastern United States. You can identify the female black widow spider by its shiny black body and distinct red hourglass-shape on the underside of the abdomen. The male black widow is smaller in size, brown or gray in color with small red sports and does not have the hourglass marking.

While both male and female black widows are venomous, only the female is dangerous to humans. The venom of a black widow is reported to be 15 times stronger than that of a rattlesnake, although they don’t deliver as much venom in their bite, so fatalities are rare. That’s not to say a black widow bite isn’t painful! Those unlucky enough to be bitten by a black widow will experience nausea, fever, sweating, restlessness, muscle cramps and labored breathing, and these symptoms may last for several days.

Brown recluse spider©Rick Vetter

As their name suggests, brown recluse spiders (Loxosceles reclusa) have a shy nature and tend to hide away in dark, sheltered places. However, the brown recluse spider will bite if they feel threatened, and their bites can be deadly. They are usually found in the south and central United States, spanning southeastern Nebraska to southwestern Ohio, south to northwestern Georgia and into Texas.

The brown recluse spider can be dangerous to people because their venom contains a toxin that can cause skin necrosis (rotting). For the most part, symptoms, such as burning and itching at the bite site, as well as fever and nausea, develop a few hours after a bite. In extreme cases, the venom can lead to serious reactions or even death, especially to more vulnerable groups such as young children and the elderly.

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Scientists complete first map of an insect brain

 

Researchers have completed the most advanced brain map to date, that of an insect—a landmark achievement in neuroscience that brings scientists closer to true understanding of the mechanism of thought.

The international team led by Johns Hopkins University and the University of Cambridge produced a breathtakingly detailed diagram tracing every neural connection in the brain of a larval fruit fly, an archetypal scientific model with brains comparable to humans.

The work, likely to underpin future brain research and to inspire new machine learning architectures, appeared in the journal Science.

"If we want to understand who we are and how we think, part of that is understanding the mechanism of thought," said senior author Joshua T. Vogelstein, a Johns Hopkins biomedical engineer who specializes in data-driven projects including connectomics, the study of nervous system connections. "And the key to that is knowing how neurons connect with each other."

The first attempt at mapping a brain—a 14-year study of the roundworm begun in the 1970s, resulted in a partial map and a Nobel Prize. Since then, partial connectomes have been mapped in many systems, including flies, mice, and even humans, but these reconstructions typically only represent only a tiny fraction of the total brain. Comprehensive connectomes have only been generated for several small species with a few hundred to a few thousand neurons in their bodies: a roundworm, a larval sea squirt, and a larval marine annelid worm.

This team's connectome of a baby fruit fly, Drosophila melanogaster larva, is the most complete as well as the most expansive map of an entire insect brain ever completed. It includes 3,016 neurons and every connection between them: 548,000.

"It's been 50 years and this is the first brain connectome. It's a flag in the sand that we can do this," Vogelstein said. "Everything has been working up to this."

Mapping whole brains is difficult and extremely time-consuming, even with the best modern technology. Getting a complete cellular-level picture of a brain requires slicing the brain into hundreds or thousands of individual tissue samples, all of which have to be imaged with electron microscopes before the painstaking process of reconstructing all those pieces, neuron by neuron, into a full, accurate portrait of a brain. It took more than a decade to do that with the baby fruit fly. The brain of a mouse is estimated to be a million times larger than that of a baby fruit fly, meaning the chance of mapping anything close to a human brain isn't likely in the near future, maybe not even in our lifetimes.

The team purposely chose the fruit fly larva because, for an insect, the species shares much of its fundamental biology with humans, including a comparable genetic foundation. It also has rich learning and decision-making behaviors, making it a useful model organism in neuroscience. And for practical purposes, its relatively compact brain can be imaged and its circuits reconstructed within a reasonable time frame.

Even so, the work took the University of Cambridge and Johns Hopkins 12 years. The imaging alone took about a day per neuron.

Cambridge researchers created the high-resolution images of the brain and manually studied them to find individual neurons, rigorously tracing each one and linking their synaptic connections.

Cambridge handed off the data to Johns Hopkins, where the team spent more than three years using original code they created to analyze the brain's connectivity. The Johns Hopkins team developed techniques to find groups of neurons based on shared connectivity patterns, and then analyzed how information could propagate through the brain.

In the end, the full team charted every neuron and every connection, and categorized each neuron by the role it plays in the brain. They found that the brain's busiest circuits were those that led to and away from neurons of the learning center.

The methods Johns Hopkins developed are applicable to any brain connection project, and their code is available to whoever attempts to map an even larger animal brain, Vogelstein said, adding that despite the challenges, scientists are expected to take on the mouse, possibly within the next decade. Other teams are already working on a map of the adult fruit fly brain. Co-first author Benjamin Pedigo, a Johns Hopkins doctoral candidate in biomedical engineering, expects the team's code could help reveal important comparisons between connections in the adult and larval brain. As connectomes are generated for more larva and from other related species, Pedigo expects their analysis techniques could lead to better understanding of variations in brain wiring.

The fruit fly larva work showed circuit features that were strikingly reminiscent of prominent and powerful machine learning architectures. The team expects continued study will reveal even more computational principles and potentially inspire new artificial intelligence systems.

"What we learned about code for fruit flies will have implications for the code for humans," Vogelstein said. "That's what we want to understand—how to write a program that leads to a human brain network."

(Image credit: Johns Hopkins University and University of Cambridge)

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Science breakthrough: ‘Uncrushable’ beetle discovery might create ‘invincible supplies’

 

By

 currentlyover

A study of the diabolical ironclad beetle’s almost indestructible shell could be an engineering breakthrough

The diabolical ironclad beetle is, as its name suggests, one tough insect. Clad in super-tough body armour, the beetle can survive the heaviest of forces – as much as being run over by a car. In all, it can withstand forces of up to 39,000 times its own weight.

Scientists are now investigating what exactly allows the diabolical ironclad to be such a force of nature.

It is hoped that their findings will enable engineers to transfer these qualities to future projects.

The new research is published in the prestigious journal Nature.

Study leader Professor David Kisailus of the University of California, Irvine, says the research could lead to never before found “tough, impact and crush-resistant materials”.

The diabolical ironclad beetle (Phloeodes diabolicus) is found mainly in the US and Mexico.

It lives in near obscurity under the bark of trees or beneath rocks.

Despite tremendous efforts, the pins bent and snapped.

They had to resort to drilling through the beetle’s outer shell in order to penetrate the casting.

It is believed that one of the main reasons why the beetle’s body is so tough is because it has lost its ability to fly.

Thus, the insect has evolved crush-resistant forewings (known as elytra), to survive being pecked to death by hungry birds.

Using microscopy, spectroscopy and mechanical testing, the researchers identified a series of interlocked jigsaw-shaped joints within the exoskeleton.

It was found that the beetle is able to withstand forces of up to 149 Newtons – approximately 39,000 times the creature’s body weight.

Scientists then went on to test the ways in which this strength could be imitated in materials.

They made a series of joints from metal and composites based on those seen in the beetle.

They say their designs enhanced the strength and toughness of the materials.

Bones, teeth and shells, as well as other natural materials have long served as inspiration for scientists seeking to develop new materials.

Recently, separate studies which looked into the force with which the mantis shrimp could use in its club-like forearms were conducted also at the University of California.

Researchers there hoped to use the genetic makeup of the ancient crustaceans in order to create engineering materials in the automotive, aerospace and sports industries.

Countless other natural-world materials have exceptional mechanical performance, as well as strength, toughness and the ability to self-heal.

FAVORITE IMAGES OF THE WEEK - 17

DEWDROP INSECT

Ondrej Pakan's gorgeous macro shots of insects bedecked with dewdrops are just about the prettiest shots of what are basically just wet bugs we've ever seen. See more here.

Ondrej Pakan

ROBOT, MEET HUMAN

Robonaut 2 has been around for a few years now, but we never get tired of its exploits. And this picture shows the R2 reaching out to touch a human. NASA notes that it and GM are working on new robotic gloves to assist astronauts and other workers.

NASA

SPIDER GUITAR

This intricate arachnophilic guitar body looks...cool, I guess, if you're into stuff like that. But what's more impressive to us is that the whole body was made with a 3-D printer. Read more here.

Olaf Diegel

BALL OF BEES

Japanese honeybees have an insane defensive ploy: they swarm around the predator (like, say, a hornet) so aggressively that the heat from their bodies actually cooks the predator. Read more here.

Wikimedia Commons

THE TITANIC, 100 YEARS LATER

The April 2012 issue of National Geographic has a cover story with incredible photos of the sunken Titanic, a hundred years after the wreck. Only the newest imaging technology has made these pictures possible. See them over at Nat Geo.

Walden Media

Plastic-eating caterpillars could save the planet

An escape from a shopping bag triggers an idea

MOST scientific research follows a logical progression, with one experiment following up on the findings of another. Every now and then, however, serendipity plays a part. Such is the case with a paper just published in Current Biology, which reveals to the world a moth capable of chewing up plastic.

The experiment behind the paper was inspired when Federica Bertocchini, an amateur beekeeper who is also a biologist at Cantabria University, in Spain, noticed caterpillars chewing holes through the wax in some of her hives and lapping up the honey. To identify them, she took some home in a plastic shopping bag. But when, a few hours later, she got around to looking at her captives she found the bag was full of holes and the caterpillars were roaming around her house.

After rounding them up, she identified them as larvae of the greater wax moth, a well-known pest of bee hives. On considering their escape from their shopping-bag prison, though, she wondered whether they might somehow be put to work as garbage-disposal agents.

Past attempts to use living organisms to get rid of plastics have not gone well. Even the most promising species, a bacterium called Nocardia asteroides, takes more than six months to obliterate a film of plastic a mere half millimetre thick. Judging by the job they had done on her bag, Dr Bertocchini suspected wax-moth caterpillars would perform much better than that.

To test this idea, she teamed up with Paolo Bombelli and Christopher Howe, two biochemists at Cambridge University. Dr Bombelli and Dr Howe pointed out that, like beeswax, many plastics are held together by methylene bridges (structures that consist of one carbon and two hydrogen atoms, with the carbon also linked to two other atoms). Few organisms have enzymes that can break such bridges, which is why these plastics are not normally biodegradable. The team suspected wax moths had cracked the problem.

One of the most persistent constituents of rubbish dumps is polyethylene, which is composed entirely of methylene bridges linked to one another. So it was on polyethylene that the trio concentrated. When they put wax-moth caterpillars onto the sort of film it had taken Nocardia asteroides half a year to deal with, they found that holes appeared in it within 40 minutes.

On closer examination, Dr Bertocchini and her colleagues discovered that their caterpillars each ate an average of 2.2 holes, three millimetres across, every hour, in the plastic film. A follow-up test found that a caterpillar took about 12 hours to consume a milligram of shopping bag. Such bags weigh about three grams, so 100 larvae might, if they spent half their lives eating, consume one in a month.

Whether releasing wax moths on the world’s surplus plastic really is sensible is not yet clear. For one thing, it has not been established whether the caterpillars gain nutritional value from the plastics they eat, as well as being able to digest them. If they do not, their lives as garbage-disposal operatives are likely to be short—and, even if they do, they will need other nutrients to thrive and grow. Another question is the composition of their faeces. If these turn out to be toxic, then there will be little point in pursuing the matter. Regardless of this, though, the discovery that wax-moth larvae can eat plastic is intriguing. Even if the moths themselves are not the answer to the problem of plastic waste, some other animal out there might be.

Enjoy a glorious rainbow of incredible bug photographs

Sam Droge USGSBIML

Velvet ants aren't the only bugs to come in a rainbow of colors.

Nature comes in all colors

By Mary Beth Griggs

Flowers are fantastic, rainbows are ravishing, but bugs are often neglected as being creepy and crawly, when in reality they're remarkably colorful. Enjoy scrolling through a rainbow of bugs.

Sam Droge USGSBIML

This Chlamisine chrysomelid looks like it crawled out of red hot lava and just kept going. This leaf beetle was collected in Cuba near Guantanamo bay in 2011.

Kelly Graninger and Anders Croft, USGSBIML

The neon-bright orange color here comes from the pollen of Arizona poppies. The bright color attracts bees like this Protoxaea gloriosa. Bees gravitate towards vibrantly colored flowers, where they gather nectar and pollen.

Sam Droge USGSBIML

This male digger bee (Anthophora californica ) from California has a bright yellow face. It looks like a wasp, but is actually a bee. Digger bees get their names because the females dig their nests in the desert soil.

Sam Droge USGSBIML

This lime green bee is from the genus Osmia and was found in San Francisco. Bees from this genus are known as mason bees and often use clay or mud to construct the interior of their nests.

blue bee

Exaerete smaragdina is a parasitic orchid bee that was collected in Costa Rica. These bees collect oils from orchids to attract mates, but they have a dark side too. They steal the nests of other bees, killing off rival eggs in the process.

Sam Droge USGSBIML

It might be a stinkbug, but this beetle is stunningly beautiful. This species–Stiretrus decemguttatus–comes in an unbelievable array of colors, including this beautiful indigo. Beetles like this one eat leaf beetles like the red one seen above.

Sam Droge USGSBIML

This vibrantly violet orchid bee of the genus Euglossa came from Guyana. As the name implies, it helps pollinate orchids. Unlike the blue example above, this bee is not parasitic.

Wayne Boo USGSBIML

The black onion fly (Tritoxa flexa) lives in North America. Its distinctive stripes make this species easy to spot. It can feed on nectar, but is also often found near garlic.

Elizabeth Garcia USGSBIML

The Thistledown Velvet Ant—Dasymutilla gloriosa—isn’t an ant at all. It’s a wasp. These strangly hairy insects have a sting that’s only mildly toxic, but immensely painful, causing predators to steer clear.