New research suggests boa constrictors do not strangle their prey, but actually use a more advanced and effective technique to subdue them.
A recent study determined that contrary to popular belief, the snakes kill their victims by cutting off blood circulation to the heart, brain, and other organs instead of slowly suffocating them, Dickinson College reported.
Past experiments have measured the pressure exerted by snakes while crushing dead rats, determining the snake's constriction is synched up with the prey's heartbeat. Now, the researchers have gained even more insight into the predatory function by measuring what is going on inside the victim itself.
"It was not something that we took lightly, and we wanted to make sure that the animals [rats] did not experience pain or suffer," said Associate Professor of Biology Scott Boback. He noted the project proposal underwent a full review by the Institutional Animal Care and Use Committee (IACUC).
The team inserted ECG electrodes and blood-pressure catheters into the rodent's body before they were sedated and fed to the hungry boa constrictor.
The researchers noted the snake aimed its bite at the rodent's head before coiling its body around the prey and squeezing. They observe the rat's blood circulation shut down in only a few 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]," Boback said.
Once the snake cut off the animal's blood circulation and oxygen supply, its heart started beating more irregularly. This suggests any creature caught by a constrictor passes out almost immediately, and does not experience its organs shutting down.
These findings could also have implication into the evolution of snakes. Ancient snake species that had not developed contriction were most likely restricted to smaller meals, but boas were able to scale up their meal size by acquiring this technique.
"By understanding the mechanisms of how constriction kills, we gain a greater appreciation for the efficiency of this behavior and the benefit it provided early snakes," Boback concluded.
The findings were published in a recent edition of the Journal Of Experimental Biology.
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