Scientists in the US have measured how boa constrictors end the lives of their prey.
The work has busted a myth that the snakes suffocate their victims.
Researchers took measurements – including blood pressure and heart activity – from anaesthetised rats gripped by the snakes.
This showed that the lethal grip restricted blood flow severely enough to cut off the blood flow supplying oxygen to its vital organs.
The findings are published in the Journal of Experimental Biology.
This “circulatory arrest”, the scientists say, is a much more efficient, rapid and definite way of finishing off prey than expected.