Boa common able to feel the heartbeat of the victim at the time of strangulation because it gives him a signal about the state of the victim, as the scientists reported. The analysis, published Wednesday in the journal Biology Letter, experts on snakes from Dickinson College in Carlisle, Pennsylvania pondered how the boa understands that its production is already in a lifeless condition and can be swallowed.
The timing is intended to stifle vital for these snakes. The fact that this process facilitates great leakage of energy reserves, increasing their metabolic rate seven times during the process of suffocation. In addition, continuing to be wound on his prey, snakes themselves can become potential prey for other predators.
The research team decided to use in the experiment "warm corpses of rats’ ability to unravel the secret of boas to measure the pulse of the victim. These were lab rats, killed humanely, frozen and then heated up to 38 degrees Celsius with an electric blanket.
Researchers in the experiment were implanted in the warm carcasses of rodents device that simulated the heart rate, and tossed the dead animals to young snakes. Typically, boas spent to stifle one rat for about 20 minutes, but the "artificial heart", as used in the experiment was set up at different times: the heartbeat lasted 10 minutes, or every 20 minutes, or even immediately cease. In the case where the so-called beating heart 20 minutes boas firmly gripped rat with equal intensity all the time, and even longer, periodically creating an additional ring around the body of a dead animal. Boas spent a rat only 10 minutes, if it is "silent", clutching prey with only half-heartedly. If you experience a heart rate for 10 minutes, the snakes grip after a few minutes then began to weaken.
"Our data show that the ability to respond to the heartbeat of the victim is an innate ability and boa snakes, since the value of the response is closely related to the experience," - said the study’s authors.