Can boiling water kill a snake

How to kill strangler snakes

Carlisle (USA) - A mammal that becomes prey to a boa does not die from slow suffocation. By entangling and choking its victim, the giant snake is blocking its blood circulation so that the animal becomes unconscious after just a few seconds and ultimately suffers cardiac arrest. American biologists conclude from their experiments with anesthetized rats, as they report in the "Journal of Experimental Biology". This is the first time they have confirmed an assumption that it is not shortness of breath, but the breakdown of the cardiovascular system that causes the death of the prey.

“We wanted to make sure the rats weren't in pain and didn't have to suffer,” said Scott Boback of Dickinson College in Carlisle. In order to research the catching technique of strangler snakes, his working group had initially offered the snakes dead animals. However, in order to be able to clarify how the victim is killed, measurements on living test animals were necessary. For this purpose, the researchers now used heavily anesthetized rats that were equipped with several measuring instruments. This enabled them to determine blood pressure readings, electrocardiograms, and changes in blood chemistry after the snake attacked. For the experiments, they brought a rat prepared in this way close to a hungry boa constrictor. This triggered a quick bite from the snake in the head or shoulder of the animal, which held the prey in place. Immediately afterwards, the snake's body wrapped around the rat's chest (Video: With each exhalation of the trapped animal, the snake tightened the noose and reached maximum pressure after six seconds. After an average of 6.5 minutes, the stranglehold was released again. In previous studies, the same researchers were able to show that the boa registers the prey's heartbeat while gagging and adapts the duration and strength of the choking pressure accordingly.

Twenty years ago, other biologists had already concluded from observations that cardiac arrest as the cause of the prey's death would be more likely than asphyxiation. This is exactly what Boback and his colleagues have now been able to demonstrate directly for the first time. In a surprisingly short time, within six seconds after the bite, the rat's arterial blood pressure fell by half and the so-called central venous pressure increased six-fold. Apparently the return of venous blood to the heart was blocked. After a minute, the heart rate had dropped almost to half and then continued to drop. The strong pressure on the chest also made breathing difficult and accelerated the rise in the level of carbon dioxide in the blood, so that the pH fell from 7.4 to 7.0. The progressively reduced blood flow to vital organs such as the brain, heart and liver eventually led to a fatal lack of oxygen in these tissues.

The results obtained with rats cannot be transferred to reptiles and amphibians, the researchers write. Because these non-warm-blooded animals have a different circulatory system and can survive a lack of oxygen much better. Either the snakes have to hold such prey in a stranglehold for much longer until they are dead, or it is eaten alive. The new results would also help to better understand the evolution of strangler snakes, says Boback. Originally, snakes that did not develop venom glands could only overpower small prey. Only a perfected choking technique enabled the predecessors of the boas to kill animals that were larger than themselves.

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