Why does a cockroach not die even after decapitation?

Why does a cockroach not die even after decapitation?

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Why does a cockroach not die after its head is cut off?

Based on an article here, unlike humans, cockroaches have an open circulatory system. They don't have a huge network of blood vessels like that of humans, or tiny capillaries that you need a lot of pressure to flow blood through. Hence after you cut their heads off, very often their necks would seal off just by clotting.

According to the article cockroaches breathe through spiracles, or little holes in each body segment. Plus, the roach brain does not control this breathing and blood does not carry oxygen throughout the body. Rather, the spiracles pipe air directly to tissues through a set of tubes called tracheae. In addition cockroaches are poikilotherms, or cold-blooded, meaning they need much less food than humans do. Hence cockroaches can survive decapitation.

Although the answers to date are all factual and sufficient to answer the question why cockroaches would live without its head, some answers don't seem to be necessary as explanations.

Summarizing the given answers so far.

  1. Roaches' simple circulation would still function without its head.
  2. Roaches' decentralized respiratory system can still function without its head.
  3. Roaches are cold-blooded and demand less energy.

However, chickens can live without its head as long as the injury does not significantly damage its brain stem, which controls the animal's vital reflexes such as respirations.

  1. Chickens do have complex network of blood vessels and capillaries.
  2. Chickens don't breathe via spiracles and do have centralized respiration system like us.
  3. Chickens are warm-blooded.

Thus, an animal (such as a cockroach) can live headless if its remaining organs can still control its "vital functions".

Cockroaches are insects which means their brain is distributed.

The predominant characteristics of the cockroach central nervous system (CNS) are its segmented nature and decentralization of control processes (Ganihar et al., 1994; Pipa & Delcomyn, 1981)

. There is a pair of ganglion on each segment- head, thorax and abdomen. The ganglion on head is controlling the antennae inputs,proboscis,mandibles,eyes etc. When we cut off its head the ability to control all the above described organs fails(although, that doesn't matter because these organs are also decapitated) & it can't eat… but the ganglion on the thorax is actually responsible for the breathing and digestion of food(with the help of ganglion on the abdomen). So if there is any food in the gut it will be normally digested and cockroach can live days consuming this energy. Also when head is gone there is no need to provide resources for the organs in head. So it can live more days by saving these resources.Plus, it can copulate if it is placed properly and this copulation is controlled by the ganglion on the abdomen.

Can Cockroaches Really Survive A Nuclear Explosion?

No, cockroaches cannot survive a nuclear explosion. While they may be able to withstand extreme radiation exposure due to the simple design of their bodies and slower cell cycles, they certainly cannot tolerate the high amount of heat energy produced immediately following the explosion.

Cockroaches are fine when they stay on the ground, but you know that things are getting serious when you see one break out its wings and start flapping around your head. Cue running around your house, screaming like a small child. Don&rsquot worry, we&rsquove all done it.

Cockroaches have been hanging around on this planet for about 200 million years now, i.e., since the Jurassic Period (when dinosaurs were still alive and well). That&rsquos a long, long time, which means they even survived the asteroid that killed those massive, planet-dominating creatures.

The myth that cockroaches will inherit the Earth in the event of nuclear warfare surfaced shortly after the United States dropped atomic bombs on Hiroshima and Nagasaki in 1945. Reports claimed that the ancient insects were the only survivors in the rubble of the wrecked Japanese cities. What exactly are these buggers made of that enables them to survive such unbelievable energy and destructive force?

5 fascinating reasons cockroaches will outlive us all

Ah, cockroaches. The scummy, skittering, pesky little pests that somehow manage to vanish whenever you flick on the bathroom light. Like Mother Nature's little Batmans. Part of what makes them so hard to control is their resiliency, which is something of a biological marvel. Here are five reasons the humble roach will outlive us all:

1. They can adapt at a scary-fast rateIn the mid-1980s, exterminators began mixing sugary roach-bait with slow-acting poisons intended to spread and wipe out entire nests. It was an effective pest-control strategy, at least at the time. But by 1993 a strange thing happened: The toxins stopped working.

A new study from North Carolina State University may have the answer. New Scientist reports that, according to biologists, the cockroaches had "tweaked their internal chemistry so that glucose tastes bitter to them." Surviving bugs then "passed their aversions on to their descendants, and Darwinian selection made it more common."

In other words, the roaches had evolved in just a few generations.

2. Females don't need males to reproduceFemales can deliver 40 to 60 live offspring per birth. Need proof? Here's a really gross video:

But laying dozens of ghostly vermin isn't their only super-efficient reproductive trait. Females are capable of what scientists term parthenogenetic reproduction, or virgin births. According to the University of Massachusetts' biology department, "The American cockroach is said to be able to produce parthenogenetic offspring under severe conditions when no males are available." Girl roaches, in theory, could run the world.

3. They could probably survive a thermonuclear warImagine this: World War III winds to a close. The last nuclear cruise missile has long since exploded, and humans are slowly being erased from the planet, leaving Earth in the capable hands feet of the Cockroach World Order. You've probably heard some variation of this scenario before. And at least in theory, it's partly true.

Mythbusters tested the effects of radiation on cockroaches in an experiment. Of a population of thousands of roaches, the team discovered that 10 percent could survive Hiroshima-level radioactive rays after 30 days of exposure. According to Slate, it may be "because [roaches] are relatively simple organisms with fewer genes that might develop mutations." Their cells divide far more slowly than human cells, affording the roach's cellular chemistry more time to fix the problems caused by radiation, like broken strands of DNA. Small wonder their fossil records date back to 300 million B.C.

4. They can hold their breath for a long timeEver wonder why pesticides are largely ineffective against large batches of roaches? It's partly because of their highly efficient breathing system. A 2009 Australian study found that cockroaches can hold their breath for five to seven minutes at a time. ABC Science reports that "oxygen flows in as required into the tracheal system through valves on the insect, called spiracles. But, sometimes, they shut their spiracles and stop breathing." Scientists think the mechanism helps regulate the insect's loss of water, especially during extended dry periods.

5. Yes, they can live without their headsHere's a no-brainer: If you or I were to have our heads cut off, we'd die. We'd lose our ability to process the most basic bodily functions, like breathing. Plus, we'd quickly bleed to death.

Cockroach physiology is a totally different story. "They don't have a huge network of blood vessels like that of humans, or tiny capillaries that you need a lot of pressure to flow blood through," Joseph Kunkel, a biochemist at the University of Massachusetts Amherst, tells Scientific American. "They have an open circulatory system, which there's much less pressure in." If a roach were decapitated, it would simply continue to breathe through its spiracles, and its neck would seal off and clot so there's no uncontrolled bleeding.

Sure, the cockroach's aimless torso would lose a huge amount of sensory information provided by its antennae and brain, and it wouldn't be able to eat anything. That said, a newly decapitated roach who just had dinner can continue surviving for weeks on end. "As long as some predator doesn't eat them, they'll just stay quiet and sit around," says Kunkel.

What a beheading feels like: The science, the gruesome spectacle -- and why we can't look away

By Frances Larson
Published February 3, 2015 12:00PM (EST)


There are lots of good physiological reasons why people find heads fascinating, and powerful, and tempting to remove. The human head is a biological powerhouse and a visual delight. It accommodates four of our five senses: sight, smell, hearing and taste all take place in the head. It encases the brain, the core of our nervous system. It draws in the air we breathe and delivers the words we speak. As the evolution­ary biologist Daniel Lieberman has written, ‘Almost every particle entering your body, either to nourish you or to provide information about the world, enters via your head, and almost every activity involves something going on in your head.’

A huge number of different components are packed into our heads. The human head contains more than 20 bones, up to 32 teeth, a large brain, of course, and several sensory organs, as well as dozens of mus­cles, and numerous glands, nerves, veins, arteries and ligaments. They are all tightly configured and intensely integrated within a small space. And people’s heads look good too. The human head boasts one of the most expressive set of muscles known to life. It is adorned with vari­ous features that lend themselves to ornamentation: hair, ears, nose and lips. Thanks to an impressive concentration of nerve endings and an unrivalled ability for expressive movement, our heads connect our inner selves to the outer world more intensely than any other part of our body.

This extraordinary engine room – distinctive, dynamic and densely packed – is set on high for all to see. Our bipedal posture means that we show off our relatively round, short and wide heads on top of slim, almost vertical necks. The necks of most other animals are broader, more squat and more muscular, because they have to hold the head out in front of the body, in a forward position. The human head, because it sits on top of the spinal column, requires less musculature at the back of the neck. There is so little muscle in our necks that you can quite easily feel the main blood vessels, the lymph nodes and the ver­tebrae through the skin. In short, it is much easier to decapitate a human than a deer, or a lion, or any of the other animals that are more usually associated with hunting trophies.

Which is not to say that it is easy. Human necks may be, compared to other mammals, quite flimsy, but separating heads from bodies is still hard to do. Countless stories of botched beheadings on the scaf­fold attest to this, particularly in countries like Britain, where beheadings were relatively rare and executioners were inexperienced. The swift decapitation of a living person requires a powerful, accurate action, and a sharp, heavy blade. No wonder the severed head is the ultimate warrior’s trophy. Even when the assassin is experienced and his victim is bound, it can take many blows to cut off a person’s head. When the Comte de Lally knelt, still and blindfolded, for his execution in France in 1766, the executioner’s axe failed to sever his head. He toppled forward and had to be repositioned, and even then it took four or five blows to decapitate him. It famously took three strikes to sever the head of Mary, Queen of Scots in 1587. The first hit the back of her head, while the second left a small sinew which had to be sawn through with the axe blade. It was hard even when the victim was dead. When Oliver Cromwell’s corpse was decapitated at Tyburn, it took the axeman eight blows to cut through the layers of cerecloth that wrapped his body and finish the job.

For all its unpredictability, when it is skillfully performed on a com­pliant victim, beheading is a quick way to go, although it is impossible to be sure how quick since no one has retained consciousness long enough to provide an answer. Some experts think consciousness is lost within two seconds due to the rapid loss of blood pressure in the brain. Others suggest that consciousness evaporates as the brain uses up all the available oxygen in the blood, which probably takes around seven seconds in humans, and seven seconds is seven seconds too long if you are a recently severed head. Decapitation may be one of the least tor­turous ways to die, but nonetheless it is thought to be painful. Many scientists believe that, however swiftly it is performed, decapitation must cause acute pain for a second or two.

Decapitation in one single motion draws its cultural power from its sheer velocity, and the force of the physical feat challenges that elusive moment of death, because death is presented as instantaneous even though beheadings are still largely inscrutable to science. The his­torian Daniel Arasse has described how the guillotine, which transformed beheading into a model of efficiency, ‘sets before our eyes the invisibility of death at the very instant of its occurrence, exact and indistinguishable’. It is surprisingly easy to forget, when con­templating the mysteries of death, that decapitation is anything but invisible. Beheading is an extremely bloody business, which is one of the reasons it is no longer used for state executions in the West, even though it is one of the most humane techniques available. Decapitation is faster and more predictable than death by hanging, lethal injection, electric shock or gassing, but the spectacle is too grim for our sensibilities.

Decapitation is a contradiction in terms because it is both brutal and effective. A beheading is a vicious and defiant act of savagery, and while there may be good biological reasons why people’s heads make an attractive prize, a beheading draws part of its power from our inability to turn away. Even in a democratic, urbanized society, there will always be people who want to watch the show. Similarly, severed heads themselves often bring people together, galvanizing them in intensely emotional situations, rather than – or as well as – repelling them. Decapitation is the ultimate tyranny but it is also an act of creation, because, for all its cruelty, it produces an extra­ordinarily potent artefact that compels our attention whether we like it or not.

Even the relationship between the perpetrator and the victim can bring surprises, because there is sometimes a strange intimacy to the interaction, occasionally laced with humour, as well as sheer brutal­ity. Each different encounter with a severed head – whether it be in the context of warfare, crime, medicine or religion – can change our understanding of the act itself. People have developed countless ways to justify the fearsome appeal of the severed head. The power that it exerts over the living may well be universal. For all their gruesome nature, severed heads are also inspirational: they move people to study, to pray, to joke, to write and to draw, to turn away or to look a little closer, and to reflect on the limits of their humanity. The irre­sistible nature of the severed head may be easily exploited, but it is also dangerous to ignore. This book tells a shocking story, but it is our story nonetheless.

The scaffold is the ultimate stage, where, for centuries, life and death were acted out for real. In the mid-eighteenth century, Edmund Burke observed that theatregoers enjoying a royal tragedy would have raced to the exit at the news that a head of state was about to be executed in a nearby public square. Our fascination with real misfortune, he pointed out, is far more compelling than our interest in hardships that are merely staged. He might have said the same today, but in the digital age, the internet mediates our view of grisly executions, simultaneously keeping us at a distance and giving us front-row seats. Today, severed heads are held up for the camera and the spectators can watch at home. During the Iraq War, the extraordinary allure of beheading videos was proved for the first time, and in no uncertain terms.

As the American and British ‘war on terror’ moved across Afghanistan and into Iraq in the years following the September 11th terrorist attacks, a new mode of killing took the media by surprise: Europeans and Americans were taken hostage by Islamic militant groups, held for ransom and then beheaded, on camera. Throughout history, criminals have been decapitated for their crimes now, the crim­inals were decapitating civilians in terrifying circumstances, and graphic videos of their deaths were circulated online for anyone to see.

The first American victim was Wall Street Journal reporter Daniel Pearl, who was kidnapped in Pakistan in January 2002. His captors demanded the release of Taliban fighters in Afghanistan, in what was to become a typically unrealistic ultimatum. They beheaded Pearl on 1 February. A few weeks later the video of Pearl’s death emerged. It started to circulate online in March, and in June the Boston Phoenix newspaper provided a link to it from their website, a move which proved extremely unpopular with commentators in the United States who scorned the paper’s ‘callous disregard for human decency’, but the Boston Phoenix site nonetheless spawned a wave of further links to the video, and discussions about the rights and wrongs of viewing Pearl’s brutal death proliferated online.

The second American to be killed in this way, and the first to be beheaded in Iraq, was Nick Berg, an engineer who was kidnapped on 9 April 2004 and killed in early May. This time, two years after Pearl’s death, Reuters made the unedited video available within days, arguing that it was not within its remit to make editorial decisions on behalf of its clients. In contrast to the video of Pearl’s execution, which was only shown on CBS as a thirty-second clip, all the major US television news networks showed clips of the Berg video, although they stopped short of actually broadcasting the beheading itself. The traditional news media refrained from showing the footage in full, but by now television producers were following the crowd rather than breaking the story it was internet users who, in the privacy of their own homes, dared to watch Berg’s beheading.

Nick Berg’s execution video quickly became one of the most searched-for items on the web. The al-Qaeda-linked site that first posted the video was closed down by the Malaysian company that hosted it two days after Berg’s execution because of the overwhelming traffic to the site. Alfred Lim, senior officer of the company, said it had been closed down ‘because it had attracted a sudden surge of massive traffic that is taking up too much bandwidth and causing inconven­ience to our other clients’. Within a day, the Berg video was the top search term across search engines like Google, Lycos and Yahoo. On 13 May, the top ten search terms in the United States were:

nick berg video
nick berg
berg beheading
beheading video
nick berg beheading video
nick berg beheading
berg video
berg beheading video
‘nick berg’
video nick berg

The Berg beheading footage remained the most popular internet search in the United States for a week, and the second most popular throughout the month of May, runner up only to ‘American Idol.’

Berg’s death triggered a spate of similar beheadings, by a number of militant Islamic groups in Iraq, that were filmed and circulated online. There were 64 documented beheadings in Iraq in 2004, seventeen of the victims were foreigners, and 28 decapitations were filmed. The fol­lowing year there were five videotaped beheadings in Iraq, and the numbers have dwindled since. In 2004, those that received the most press attention proved particularly popular with the public. In June, an American helicopter engineer, Paul Johnson, was kidnapped and beheaded on camera in Saudi Arabia, and in the weeks after his death the most popular search term on Google was ‘Paul Johnson’. When the British engineer Kenneth Bigley was kidnapped in Iraq in September 2004 and beheaded by his captors the following month, one American organization reported that the video of his death had been downloaded from its site more than one million times. A Dutch web-site owner said that his daily viewing numbers rose from 300,000 to 750,000 when a beheading in Iraq was shown.

High school teachers in Texas, California and Washington were placed on administrative leave for showing Nick Berg’s beheading to their pupils in class. When the Dallas Morning News printed a still image of one of Berg’s assailants holding his severed head, with his face blocked out, it said that its decision had been inspired by interest generated in the blogosphere. The paper’s editorial pointed out that ‘[o]ur letters page today is filled with nothing but Berg-related letters, most of them demanding that the DMN show more photos of the Berg execution. Not one of the 87 letters we received on the topic yes­terday called for these images not to be printed.’

It is, of course, impossible to know how many people actually watched the videos after downloading them, but a significant number of Americans wanted to see them and discuss them, particularly the video of Berg, who was the first American to be beheaded in Iraq, and whose execution was the first to be recorded on camera since Pearl’s, two years earlier. Berg was killed just as public support for the war in Iraq was beginning to decline, and the popularity of the video underlined the extent to which the internet had eclipsed more traditional news media when it came to creating a story. Television news producers may have edited their clips of the video, but it did not matter because people were watching the footage online. The internet allowed people to protest against the perceived ‘censorship’ of the mainstream media, or else simply circumvent the media altogether when the mood took them. Whether people thought it ‘important’ to see Berg’s execution for themselves, or simply watched out of curiosity, there can be little doubt that ‘the crowd’ was taking control, or was out of control, depending on your perspective.

One survey, conducted five months after Berg’s death, found that between May and June, 30 million people, or 24 per cent of all adult internet users in the United States, had seen images from the war in Iraq that were deemed too gruesome and graphic to be shown on tele­vision. This was a particularly turbulent time during the war that saw not only Berg’s beheading, but also the release of photographs show­ing the abuse of prisoners at Abu Ghraib by American military personnel, and images showing the mutilated bodies of four American contract workers who had been killed by insurgents in Fallujah, dragged through the streets and hung from a bridge over the Euphrates. Nonetheless, Americans were seeking these images out: 28 per cent of those who had seen graphic content online actively went looking for it. The survey found that half of those who had seen graphic content thought they had made a ‘good decision’ by watching.

The decision to view Berg’s beheading became politicized online. Bloggers claimed it was no coincidence that the liberal news media dwelt on the harrowing images from Abu Ghraib, which undermined the Bush administration’s credibility in Iraq, while – as they saw it – sidestepping the Berg story by giving it fewer column inches and refus­ing to show the full extent of the atrocity. ‘One day the media was telling us we had to see the pictures from Abu Ghraib so we could understand the horrors of war,’ Evan Malony wrote. ‘But with Berg’s beheading, we’re told we can’t handle the truth . . . The media that had – rightfully, in my opinion – showed us the ugly reality of Abu Ghraib prison refused to do the same with Berg’s murder.’ Professor Jay Rosen was more explicit: ‘They aren’t showing us everything: the knife, the throat, the screams, the struggle, and the head held up for the camera. But the sickening photos from Abu Ghraib keep showing up.’

Other viewers admitted to watching execution videos simply out of curiosity, with no ‘higher’ purpose. One anonymous internet user said, ‘You almost can’t believe that a group of people could be so pitiless as to carry out something so cruel and bestial, and you need to have it confirmed . . . Watching them evokes a mixture of emotions – mainly distress at the obvious fear and suffering of the victim, but also revul­sion at the gore, and anger against the perpetrators.’ Meanwhile, website editors expressed a similar range of attitudes towards showing the content. They made the videos available either because they were dedicated to the fight against terror (people should see) or because they were opposed to the ‘censorship’ of the mainstream news media (people should be able to see), while ‘shock sites’ posted the footage purely as macabre entertainment alongside the other violent and provocative videos that drew their clients (watch this!).

Decapitation videos draw viewers who watch unapologetically and viewers who watch despite their own deep misgivings, and the internet offers everyone anonymity. The camera promises spectators a degree of detachment, but the action is only a click away, and this combina­tion gives the videos far greater reach. As the military analyst Ronald Jones put it, with little more than a camcorder and internet access, a militant group can create an ‘international media event . . . that has tremendous strategic impact’. Indeed, as terrorist attacks go, decapi­tating your victim on camera is an extremely efficient and effective strategy. It requires little money, training, equipment, weaponry or explosives: beyond the initial kidnapping, it does not rely on compli­cated coordination or technology that might fail, and the results are easy to disseminate. According to Martin Harrow, another analyst, it is a strategy that ‘has maximum visibility, maximum resonance and incites maximum fear’.

No wonder, then, that the Iraq hostage beheadings were ‘made for TV’. Other terrorist activities, like suicide attacks or bombings, are hard to capture on camera because they are necessarily clandestine, unpredictable and frenetic events, but the decapitation of a hostage can be carefully stage-managed, choreographed and rehearsed while still remaining brutally authentic. The footage is clear and close up. The murderers are offering their viewers a front-row seat at their show and what they want to show is their strength, their organization, their com­mitment to the cause, their complete control and domination of their victim. When one Italian hostage, a security officer named Fabrizio Quattrocchi, jumped up at the moment he was about to be shot by his captors on film and tried to remove his hood, shouting, ‘Now I’ll show you how an Italian dies!’, Al Jazeera withheld the resulting video because it was ‘too gruesome’. Was this a small victory for Quattrocchi in the face of certain death? No one saw the footage of his murder online, either for entertainment or for education, and his captors could not capitalize on his death in the way that they had planned.

During these carefully staged execution rituals, everyone, even the victim, must play their part. The whole procedure is a piece of theatre designed to create power and cause fear, just as with state executions stretching back to the thirteenth century, except, as John Esposito, a professor at Georgetown University, pointed out, when it comes to exe­cutions like Berg’s, ‘it’s not so much the punishing of the individual as the using of the individual’. Even when the victim is an innocent hostage, the power that comes from killing is exerted over a wider com­munity. The crowd is compliant too. By turning up to see the show, or by searching Google for the latest execution video, the people watching also have their part to play.

‘The point of terrorism is to strike fear and cause havoc – and that doesn’t happen unless you have media to support that action and show it to as many people as you can,’ said one analyst interviewed by the Los Angeles Times shortly after Nick Berg’s execution. These mur­derers post their videos on the internet because they know that the news media will be forced to follow the crowd. Television news pro­grammes either become redundant by refusing to air videos that are freely available online, or else they do exactly what the murderers want and show the footage to a wider audience. Meanwhile, the internet pro­vides a ‘void of accountability’, in the words of Barbie Zelizer, where it is unclear who took the images, who distributed them and who saw them. The whole experience is lost in the crowd.

Adapted from "Severed: A History of Heads Lost and Heads Found" by Frances Larson. Copyright © 2014 by Frances Larson. With permission of the publisher, Liveright Publishing Corp. All rights reserved.

Frances Larson

Frances Larson is an honorary research fellow in anthropology at Durham University. She is the author of a biography of Henry Wellcome, "An Infinity of Things," published to considerable critical acclaim and subsequently shortlisted for the MJA Awards and chosen as a Sunday Times Book of the Year as well as a New Scientist Best Book of 2009. She is also the co-author of "Knowing Things," a book on the history of the Pitt Rivers Museum in Oxford. Larson lives in Durham, England.

They are fighters. So even if their heads are the only body part they have, they still strike and defend themselves for hours. Snapping turtles have sharp beaks that can cause great injuries, and they still can attack without their bodies.

No matter how they lost their heads, flies can still walk and fly for days and weeks. A fly’s brain is in its back which means it can continue to live. Fly absorbs oxygen through their skin, and they live for days until they starve to death.

Here’s Why It’s So Hard to Smash a Cockroach

For people bent on destroying cockroaches, the act of actually squashing them can feel like a game of Whack-a-Mole. The little critters are maddeningly good at running, and once they do get smooshed, they often stand up and scuttle away. Now, writes Elizabeth Pennisi for Science, new research reveals why—and the results could help scientists build better robots.

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In a paper published in Proceedings of the National Academy of Sciences, researchers describe just how much weight cockroaches can take before succumbing to force. They put cockroaches through a grueling obstacle course of tunnels that got smaller and smaller, filmed them with a high-speed camera, and even crushed the cockroaches under different weights.

What they found was a surprising combination of agility and flexibility. Cockroaches compressed their bodies between 40 and 60 percent while traversing the tiny corridors, showcasing what researchers call “an unexplored mode of locomotion—‘body-friction legged crawling.’”

Pennisi explains how it works:

The roach first inspects the opening with its antennae. Then it jams its head through, follows with its front legs, and begins pulling the rest of its body into the breach. The back legs splay but continue to push. In about 1 second, it emerges on the far side unscathed.

The team also found that cockroaches’ exoskeletons allowed them to withstand weights up to 300 times their own body weight in small crevices and a whopping 900 times their body weight in other situations. That flexible, strong exoskeleton seems to be the secret to both their invulnerability to squashing and their ability to scuttle off when chased or threatened.

Not content to simply chase and crush cockroaches, the team also designed a soft robot modeled on roaches. It’s not the first cockroach robot, but it could one day save lives. The origami-style robot can swiftly squeeze through cracks—a skill that could help future first responders get a view of unstable or dangerous terrain without endangering humans.

Then again, the ability to navigate tight spaces and scurry away without harm could give surveillance activities or dastardly parties a leg up. Perhaps in the future, the cockroaches you’ll really want to crush will be robotic ones. 

Cockroaches are not radiation-proof and most are not pests

Reputation: Yuck. Cockroaches are filthy, immortal scavengers that are unaffected by radiation. In a post-apocalyptic world, it will be these dirty little critters that survive. We would be better off without them.

Reality: There are almost 5,000 species of cockroaches, of which only around 30 have any pest-like tendencies. These few malign a group of insects that boasts an astonishing, enriching diversity of forms. Cockroaches are pretty well toasted by radiation.

The sight of a cockroach scuttling across the kitchen floor is distinctly unsavoury. This emotional truth has led most of us to believe that all cockroaches must be similarly repugnant.

But not George Beccaloni, curator of orthopteroid insects at the Natural History Museum in London, UK. He is on the side of the cockroaches. "People have a very biased view of the group," he says.

Cockroaches are found on all continents apart from Antarctica, from rainforests to deserts

Less than 1% of the 4,800 known species of cockroach cause humans any bother, yet few of us give the 99% a second thought. This is manifestly unfair, says Beccaloni.

He points out that there are about as many cockroach species as there are mammals. So writing off all cockroaches, based on our dislike of 30 or so species, "is like encountering a mouse or a rat and then branding all mammals as disgusting vermin," he says.

I take the point, but remain unconvinced. Mammals are spectacularly diverse. I think back to a childhood holiday in Sardinia, where our flat was plagued by cockroaches. How different can the rest of cockroaches be? Beccaloni takes the next half hour to enlighten me.

For a start, they live in a huge range of habitats.

"Cockroaches are found on all continents apart from Antarctica, from rainforests to deserts," says Beccaloni.

The appealingly-named Megaloblatta blaberoides boasts a whopping wingspan of over 7in (18cm)

The abundance of species is greatest in the tropics, and at low altitudes where temperatures are high. However, there are those can cope with extremes. Eupolyphaga everestiana is a montane specialist that lives on Mount Everest at well over 16,400ft (5,000m) above sea level.

Since they live in so many diverse environments, it is not surprising that cockroaches should come in many different shapes and sizes.

The smallest species on record is the ant cockroach, which lives in the nests of leaf-cutter ants in North America. At just a few millimetres long, it is dwarfed by its hosts.

In contrast, the appealingly-named Megaloblatta blaberoides boasts a whopping wingspan of over 7in (18cm).

Larger still is the giant burrowing cockroach from Queensland, Australia. It is wingless, about 3in (8cm) long, and can weigh over 1oz (30g).

Cockroaches of the Perisphaerus genus can roll up into an armadillo-like defensive ball

This cockroach, which would easily occupy most of your palm, might sound alarming. But it could not care less about humans. "The huge rhinoceros cockroach only feeds on bark and dead leaves," says Beccaloni.

Most cockroaches have taken on similar ecological roles, feeding on decaying organic matter and thus making nutrients available to other organisms. "There are indications that the ecological significance [of cockroaches] is massive," says Beccaloni.

For many species, even some humans, cockroaches are also a sought-after snack. This helps explain why many in the group have evolved nifty ways to avoid being eaten.

The banana cockroaches (Panchlora) have opted for a simple camouflage approach: they are green and this helps them to blend in.

Cockroaches of the Perisphaerus genus can roll up into an armadillo-like defensive ball.

The females churn out perfect clones of themselves without any need for males or copulation

The Prosoplecta species have evolved the same distasteful red-and-black colouration as ladybirds. In order to achieve the rounded shape of a ladybird, Beccaloni says, each of their hind wings rolls up at the ends "like an umbrella around itself".

Some species can fire out a defensive spray, like the Pacific beetle cockroach.

Others, like the Madagascan hissing cockroach, make startling noises when disturbed, presumably to unsettle any would-be predators.

Perhaps inevitably, cockroaches have also come up with a plethora of ways to make more cockroaches.

"Cockroaches as a group are one of the most if not the most varied of all insect groups, in terms of their reproductive biology," says Beccaloni.

A few species appear to be wholly parthogenetic. The females churn out perfect clones of themselves without any need for males or copulation. In others, the females can flip between sexual and asexual modes of reproduction depending on the conditions.

The nymphs have razor-sharp mandibles, which they use to slice into her cuticle and feed on her blood

However, in most species the female produces an egg sac. Some simply lay it and move on, but others incubate the egg case in a brood pouch in their body, effectively giving birth to live young.

Pacific beetle cockroaches have abandoned egg cases altogether. The female deposits eggs directly into her brood pouch. There she nurtures them on a milk-like secretion &ndash "the most nutritious energy-rich protein that's yet been discovered," according to Beccaloni &ndash before giving birth to live, well-developed young.

If this sounds familiar, it should. "It's a very similar situation to the placenta of a mammal," says Beccaloni.

In a few cases, the female even cares for her offspring after birth.

For instance, a Thorax porcellana mother carries her babies huddled beneath her forewing. It sounds almost cute, until you learn that the nymphs have razor-sharp mandibles, which they use to slice into her cuticle and feed on her blood. "They are like little vampires," says Beccaloni.

With so many extraordinary adaptations, it would not come as much of a surprise to find that cockroaches really could survive a nuclear blast. But tolerance of radiation is one talent they lack.

There are about as many cockroach species as there are mammals

"It's mostly an urban myth," says Beccaloni.

A human will usually be killed outright by a dose of 10 Grays. "Cockroaches are only about five times more resistant," says Beccaloni.

At first glance that might sound impressive, but it actually means they "are at the lower end of radiation tolerance for insects," he says. Other species can survive doses of radiation ten times as intense, or even higher.

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Why is it so hard to squash a cockroach?

Insects, whether they creep or fly, live in a world of hard knocks. Who has not stepped on a cockroach, then raised her shoe to watch the creature get up and scoot under a door? Bees and wasps, for their part, face a never-ending obstacle course of leaves, stems, and petals—bumblebees crash their wings into obstacles as often as once a second. Now, researchers are learning how these creatures bend but don’t break.

The results do more than explain why cockroaches are so hard to kill. By mimicking the combination of rigid and flexible parts that gives insect exoskeletons and wings their resilience, biomechanicists are making robots tougher. “Bend but not break is a lot of what happens in these insects,” says Harvard University roboticist Robert Wood. “We’re trying the same thing to see if we can have similar robustness in our robots.”

Until recently, most engineers designed for a tough-and-tumble world by making machines stiff and sturdy or agile enough to avoid danger. Modern cars incorporate a third approach: They absorb impacts by crumpling, sacrificing the structure to protect the occupants. “Nature has come up with a tactic that we don’t have,” says David Hu, a mechanical engineer at Georgia Institute of Technology in Atlanta. “Crumple … and then keep on going.”

To see how cockroaches do it, integrative biologist Robert Full at the University of California (UC), Berkeley, and Ph.D. student Kaushik Jayaram coaxed the insects through ever smaller slits or tighter tunnels while filming them with a high-speed video camera. They also lowered weights of up to 100 grams onto different parts of the insects’ bodies and watched how the creatures collapsed.

Full and Jayaram found that when the 9-millimeter-tall Periplaneta americana approaches a slit no more than 3 millimeters high, the roach first inspects the opening with its antennae. Then it jams its head through, follows with its front legs, and begins pulling the rest of its body into the breach. The back legs splay but continue to push. In about 1 second, it emerges on the far side unscathed. That ability to squeeze through a tight spot “goes far beyond any other animals that we have measured, except maybe the octopus,” says Stacey Combes, a biologist at UC Davis. But an octopus—a model for the “soft” robots some designers are pursuing—can’t match the speed of a cockroach or other arthropods. “Not only insects, but crabs, spiders, and scorpions are pretty good at going anywhere and are pretty indestructible,” Full says.

Jayaram and Full’s study, published this week in the Proceedings of the National Academy of Sciences, showed that the cockroach’s secret lies in a hard but still flexible exoskeleton. It consists of hard yet bendable plates—capable of efficiently transmitting energy to its legs—connected by elastic membranes that allow the plates to overlap as the insect compresses. Thanks to spines that give traction when its legs are splayed, a cockroach can scuttle even at maximum scrunch.

At a meeting of the Society for Integrative and Comparative Biology last month in Portland, Oregon, Harvard postdoc Andrew Mountcastle reported that a similar blending of hard and soft parts enables bees and wasps to survive their aerial obstacle courses. Using high-speed video, he found that wasp wings actually buckle during collisions and then snap back into place. He also noticed that the wings have a big patch of an elastic protein called resilin about 65% down the wing. He and Combes hypothesized that the patch serves as a hinge.

To test the idea, Mountcastle developed a way to mount a wasp on a rotational motor and hit the wing over and over. “He showed the wing can pop out many, many times,” Hu says. When Mountcastle splinted the hinge so the wing couldn’t buckle, the wing quickly wore down. He and Combes also found that many insects have a similar hinge, but that bumblebee wings incorporate a different design principle. The veins that support the bee wing are concentrated close to the body, resulting in a flexible wingtip that can bounce off obstacles with less wear and tear. “It’s different means to the same ends,” Mountcastle says.

Both the roach exoskeleton and the insect wings are inspiring robot design. Jayaram has built a 75-millimeter-tall robot, called CRAM, with a roachlike collapsible exoskeleton and legs with “spines” that work both in the uncompressed and compressed positions. It can squeeze to one-half its height and still move 5 to 10 times faster than soft robots, Jayaram says. “What is exciting is that this gives us an order of magnitude reduction in voids where we can deploy robots,” says Robin Murphy of Texas A&M University, College Station, who specializes in robots for disaster search and rescue operations.

Mountcastle has joined forces with Jayaram—now also a Harvard postdoc—and Wood to refit hinged wings to an insect-sized flying robot called Robobee. “Designing [it] was not trivial they are not simple, linear hinges,” Mountcastle said at the Portland meeting. The group hopes begin testing the new design in the real world by spring.

Hu applauds the insect-inspired designs: “It would be great to see more robots built with potential damage in mind.” As for killing cockroaches—Jarayam suggests slamming that shoe hard and holding it down.

Insecticides adversely affect the nervous system of cockroaches

A cockroach&rsquos legs (6 legs in total) need constant nerve stimulation to remain in a &lsquotucked&rsquo position beneath the body. Look at the following image for a better visualization of this:

This is the normal &lsquotucked&rsquo position of a cockroach&rsquos legs (Photo Credit : Masterbutler / Flickr)

In simple words, a healthy cockroach has its legs a bit curled up, thanks to a bunch of nerves for each pair of legs that provide constant stimulation and help control its movements. That&rsquos why a headless cockroach can still move around erratically and try to re-orient itself before dying. (Source)

Most insecticides are neurotoxins (organophosphate nerve poisons). These poisons tend to inhibit an enzyme called cholinesterase, which breaks down a neurotransmitter called acetylcholine (ACh). The direct upshot of this is that the cockroach&rsquos nervous system gets an excess of ACh, which can then trigger muscular spasms and tremors (little seizures, if you will). This results in the intoxicated cockroach toppling over on its back. What compounds the plight of the poor insect even more is that&hellip

Frequently Asked Questions

Cockroach baits and roach motels attract the roaches that are already there they aren’t going to bring more roaches into your house. You might think you’re seeing more roaches after putting down bait but you’re simply noticing the ones that have been hiding all along.

It depends on the size of the roach problem and the type of roach motel, but roach motels could last anywhere from a few days to a few months.

Sticky motels like Exterminator’s Choice or Black Flag for example, should continue to attract roaches for a few months or more, or until they fill up and there are no sticky surfaces left.

Baited roach motels are better-suited to being left out for long periods. Unless you have a truly massive infestation, it will take a while for roaches to completely gobble up the bait, and the insecticide will probably last a year.

Written by Andrew Martin. Reviewed by James Miksanek, PhD.

Disclaimer: This page is strictly for informational use. When using insecticides, keep in mind—the label is the law. Insecticides should be applied correctly and safely when needed, and according to the laws of your state or country.

Watch the video: Cockroach Infestation. National Geographic (September 2022).


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