Death by suffocation seems like an awfully protracted way to go and death by suffocation in the grip of a boa constrictor's coils is the stuff of nightmares. Yet Scott Boback from Dickinson College, USA, wasn't so sure that suffocation was all there was to the boa constrictor's technique. 'It looks like the [prey] animals are gasping for air', says Boback, but in 1994, Boback's colleague, Dave Hardy, had proposed an alternative. 'What Hardy saw was the speed at which the animals were dying... they were dying way too quickly for it to be suffocation. He suspected that it was circulatory or cardiac arrest because of the speed at which death was occurring', says Boback. But there were few data to support Hardy's suggestion and, although hard-core members of the herpetology community were aware of the possibility, the rest of us were left clinging to the old-wives' tale that constricting snakes kill by suffocation: until Boback put the crushers to the test. He and his colleagues publish their discovery that boa constrictors rapidly shut down the victim's circulation. They suggest that the snakes kill their prey by cutting off the blood supply to the heart, brain and other vital organs causing their victims to pass out in a matter of seconds and die more quickly than if they were being suffocated in The Journal of Experimental Biology at http://jeb. biologists. org . 
 
 'We have been studying constriction for a number of years,' says Boback, explaining that he had measured the pressure exerted by snakes crushing dead rats in earlier experiments. However, to find out what was really going on inside the snake's victims, he had to measure blood pressure in living anesthetised rodents as they were squeezed. 'It was not something that we took lightly and we wanted to make sure that the animals [rats] did not experience pain or suffer', says Boback. Having anesthetised a rat, Boback and his colleagues, Emmet Blankenship and Charles Zwemer - backed up by undergraduate researchers, Katie McCann, Kevin Wood and Patrick McNeal - inserted ECG electrodes and blood pressure catheters into the rodent's body before offering the sedated animal to a hungry boa constrictor. 
 
 Fortunately for Boback, the snake struck, aiming a bite at the rat's head and coiling its body around the rodent as it began to squeeze. And, as the team watched the blood pressure and heart rate data stream onto the computer, they were amazed to see the rat's blood circulation shut down in a matter of seconds. 'I remember being in the room and the students were looking at the data in disbelief that it happened that fast. We could see the arterial pressure go down, the venous pressure go up and we could see this right when the snake was doing it [squeezing]', says Boback. As soon as the rat's circulation stopped and the oxygen supply was cut off, the team could also see the rat's heart beating more and more irregularly. Boback suspects that without blood flow to the brain, any animal caught in the snake's coils probably passes out in a matter of seconds, before other critical organs begin to fail. 
 
 Boback also suggests that the boas provide a glimpse into the evolution of crushing behaviour in snakes. He explains that ancient snake species that had not evolved constriction were probably restricted to capturing small meals that they could subdue easily. However, once the earliest boas had developed their quicker constriction technique for despatching victims, they were free to scale up the size of meals, sometimes tackling animals that are even larger than themselves. 'By understanding the mechanisms of how constriction kills, we gain a greater appreciation for the efficiency of this behaviour and the benefit it provided early snakes', says Boback. 
 
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 REFERENCE: IF REPORTING THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: jeb.biologists.org/lookup/doi/10.1242/jeb.121384 
 
 REFERENCE: Boback, S. M., McCann, K. J., Wood, K. A. , McNeal, P. M., Blankenship, E. L. and Zwemer, C. F. (2014). Snake constriction rapidly induces circulatory arrest in rats. J. Exp. Biol. 218, 2279-2288. 
 
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 THIS ARTICLE IS EMBARGOED UNTIL WEDNESDAY, 22 July 2015, 18:00 HRS EDT (23:00 HRS BST) ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| Boa constrictors were long thought to kill their prey by suffocation, slowly squeezing the life out one ragged breath at a time. 
 
 But a new study reveals that these big, non-venomous serpents, found in tropical Central and South America, subdue their quarry with a much quicker method: Cutting off their blood supply. 
 
 When a boa tightens its body around its prey, it throws off the finely tuned plumbing of the victim's circulatory system. Arterial pressures plummet, venous pressures soar, and blood vessels begin to close. ( Read how snakes know when to stop squeezing their prey .) 
 
 "The heart literally doesn't have enough strength to push against the pressure," says study leader Scott Boback , a vertebrate ecologist at Dickinson College in Carlisle, Pennsylvania. 
 
 Most animals can actually survive a relatively long time without breathing: Think about drowning people who are later resuscitated, he says. But the same isn't true for a body without a heartbeat. 
 
 If executed perfectly, the powerful squeeze causes the animal to pass out within a matter of seconds. Death follows soon after. 
 
 Snakes on a Vein 
 
 To better understand the snakes' constriction mechanism, Boback and his colleagues at Dickinson anesthetized lab rats and then rigged the animals with various instruments. 
 
 Vascular catheters measured blood pressure, for instance, while electrodes secured within the rats' chest cavities provided information about the heart's electrical activity. (Also see "Pictures: How a Python Can Swallow a Crocodile.") 
 
 Then they fed the outfitted rats to captive boa constrictors and measured what happened to the lab rats. Surprisingly, the pressures at which the snakes cinched against the rats weren't all that remarkable. But then again, they don't need to be. 
 
 "A boa constricting a small rat is generating the kind of pressure that would stop the blood flow in your arm," says Boback, whose study appears July 22 in the Journal of Experimental Biology. 
 
 But even this light pressure, when applied to a rat's torso, makes its system goes haywire, the team discovered. (See "Giant Python Meals That Went Bust.") 
 
 Once blood flow ceases, organs with high metabolic rates—such as the brain, the liver, and the heart itself—begin to shut down. Doctors call this ischemia . 
 
 Snakes call it lunch. 
 
 An Evolutionary Advantage 
 
 The team theorizes that killing by circulatory arrest has given all constricting snakes—which includes pythons and anacondas —an evolutionary advantage. The quicker the snakes can disable their prey, the lower the chance the predator will get hurt in the process. 
 
 "That absolutely makes sense," says Paul Rosolie , a conservationist who has spent the last decade working with anacondas. 
 
 Think about other animals living alongside boa constrictors in tropical rain forests , says Rosolie: They have teeth, hooves, and claws capable of kicking and ripping. But a snake just has a mouth—making it extremely vulnerable. ( Watch a video of an anaconda taking down its prey .) 
 
 "Almost every time an anaconda takes something down, it's putting its face on that animal," says Rosolie, who wasn't involved in the new research. 
 
 "If it doesn't get the attack exactly right, something big like a capybara can chew right through the body of an anaconda." 
 
 Watch a video of an anaconda stalking a capybara. 
 
 Anaconda Hunts When you're an anaconda, you don't need venom to take down your prey, even if it's the world's largest rodent, a capybara, weighing nearly 100 pounds (45 kilograms)! 
 
 
 
 
 
 Ectotherm's Revenge 
 
 As interesting as his revelation is, Boback says there's still much we don't know. 
 
 For instance, there's evidence that boa constrictors have a tougher time killing ectotherms, animals such as lizards and snakes that rely on external heat to regulate their body temperatures. 
 
 During a recent expedition to Honduras , for instance, Boback and several other scientists observed a boa constrictor attacking a spinytail iguana . After the snake constricted its prey for an hour, the team collected both animals—assuming the iguana was dead—and went to bed. 
 
 In the morning, they were surprised to discover the animals at either end of the observation tank, with the iguana alive and well. (Also see " Freshly Eaten Snake Makes Amazing Escape—Find Out How .") 
 
 "We have no idea what was going on," says Boback, "but [the iguana] seemed totally fine." 
 
 No worse for wear, the team released the lucky survivor back into the wild.
– Most people think constrictors like boas and anacondas squeeze the air out of their prey with their muscular coils. And most people are wrong, according to a new study that offers an entirely different theory. Dickinson College researcher Scott Boback explains that colleague Dave Hardy first noticed two decades ago that the speed at which prey die in the clutches of a boa is far too quick to be from suffocation—a painful, drawn-out process, per a release. He supposed an animal's death was caused by circulatory or cardiac arrest, says Boback, but there were no studies to back him up. Twenty years later, Boback says his study in the Journal of Experimental Biology proves Hardy was right: Boas cut off prey's blood flow to the heart, brain, and other vital organs by closing blood vessels and sending pressure in the arteries plummeting. The animals pass out in seconds and die relatively quickly, researchers say. It wasn’t pleasant work coming to that conclusion. Researchers anesthetized 24 rats, put ECG electrodes and vascular catheters into their bodies to monitor heart rate and blood pressure, then watched as they were squeezed by nine boa constrictors, reports Smithsonian. After six seconds, a rat's blood circulation dropped by half. "I remember being in the room and the students were looking at the data in disbelief that it happened that fast," says Boback. The oxygen supply was eliminated within the next minute as the rat's heartbeat began to falter. After six minutes, more than 90% of the rats had died, likely from irreparable heart damage as their veins were crushed, though they were probably unconscious from the first seconds, Boback says. "The heart literally doesn't have enough strength to push against the pressure," he tells National Geographic. Boback adds snakes' quick crushing skills probably evolved to protect them from prey with sharp teeth and claws. (Snakes once had ankles.)