Boa constrictors are widely believed to kill prey by cutting off the air flow and suffocating it. But a new study has revealed that this is a flawed line of thought. In reality, Boa constrictors kill prey by cutting off the blood flow and giving heart attacks.
The study was conducted on rats and found that the boa snake’s tight coil cuts off the rodent’s blood flow and subdues it much faster than if the small animal was being suffocated. The prey fights back less and the predator saves time and energy while acquiring its next meal. A good constriction should kill prey in just a few short seconds.
Scott Boback, lead researcher and associate professor of biology from Dickinson College (Pennsylvania), gave a statement saying that “This is such an efficient behavior, and it allows us to realize that this behavior was really important in snake evolution”.
He quickly went on to add that the constriction is so efficient at killing that the prey literally doesn’t have the strength to fight back against the pressure. The lead researcher also mentioned that the confusion is understandable as the prey often looks like it’s gasping for air.
But it’s important to know that most animals can in fact survive a fairly long time without needing to breathe. The phenomenon is not dissimilar to people who’ve drowned, but who’ve been rescued and resuscitated. But a body with a heart that’s stopped beating can not be resuscitated if the condition lasted for fairly long time.
While this is the first study to prove without a doubt that boa snakes don’t suffocate their prey, other researchers have suggested the notion in the past. A very early example dates back to 1928, and a second one, conducted by Dr. David Hardy, dates back to 1994.
Professor Boback explained that Dr. Hardy, an anesthesiologist and snake expert, focused on the speed of the kill when he wrote his study. Animals were simply dying too quickly for the cause of death to be suffocation. In his paper, the doctor stressed that suffocation can take several minutes to kill prey, whereas circulatory arrest will never take longer than 60 seconds.
For their study, Professor Boback and his team first performed surgery on rats and implanted electrocardiogram electrodes that helped them measure the heart rates of the rats. They also put blood pressure catheters into the rodents’ major arteries and veins. It was important for the team to use both a vein and an artery because they wanted to observe “both sides of the circulatory system”.
On top of everything, the researchers added a pressure probe into the rats and took blood samples from them. They then gave the rats anesthetics and gave them away to the boa snakes to test how they responded to constrictions.
After the rodents died, the research team quickly collected them before the snakes had time to feed and took another blood sample from each of the deceased rats.
What the data collected from the sensors showed was that the rats’ blood circulation was shut down only a few seconds after the attack took place. Their arterial pressure dropped, which means that oxygenated blood was not being pumped throughout their bodies. The venous pressures also rose, which indicates that the pressure exhibited by the constriction was too high to allow blood to return back to the heart.
Boa snakes are gorgeous, badass creatures than can be found living in Central America and South America. They’re non-venomous animals, but they’re also some of the biggest snakes on our planet.