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Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
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ScienceShot: I Can Feel Your Heartbeat ... Stop
17 January 2012 7:01 pm
The heart wants what the heart wants, and boa constrictors want the hearts in their prey to stop beating. New research reveals that the snakes stop squeezing when they sense their prey's heart stop. In the study, scientists inserted a tiny, water-filled bulb next to the hearts of dead rats, and pumped water in and out of it to mimic heartbeats. The researchers also warmed the rodents to their living body temperature of 38°C. Then they let the snakes at them. Although wild-caught boas squeezed harder than captive-bred snakes, both stopped constricting shortly after the fake rat heart stopped beating, the team reports online today in Biology Letters. The authors speculated that boas evolved their sensitivity to heartbeats early on, when they went after cold-blooded animals that could survive for hours on little oxygen; just because their prey stopped struggling didn't necessarily mean they were dead. Constriction requires an enormous amount of energy—seven times what the snake spends while resting—so once an animal is deceased, the reptiles can save their strength for eating it.
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