https://www.youtube.com/watch?v=IJCYUf3IhSs
Experiments with vampire bats that walk on treadmills have revealed that they have a very unusual method of obtaining energy from protein due to their specialized diet.
Most mammals get most of their energy to move from fat and stored sugars, but all three species of vampire bats subsist on a diet of blood drawn from their victims, which is rich in protein but low in fat and sugar. So how their metabolism works is unclear, since the amino acids that make up proteins typically supply less than 10 percent of the animals’ energy during exercise.
To learn more about their metabolism, Kenneth Welch and Giulia Rossi At the University of Toronto in Canada, he studied 24 adult common vampire bats (Round desmodus) captured in Belize. The bats were fed cow’s blood containing amino acids marked with carbon atoms, then placed on tape in a small box.
The metabolic rate of the bats was measured by monitoring the intake of oxygen and the expiration of carbon dioxide while walking on the treadmill at speeds of up to 30 meters per minute. By analyzing exhaled carbon isotopes, the researchers found that they were extracting energy from their last meal, rather than stored fat or sugar.
Welch came up with the experiment 20 years ago while researching how hummingbirds use sugar in nectar, discovering similarities with nectar-feeding bats. Did you know that tsetse flies (Glossina morsitans) fed on blood and was unusual in that it didn’t use fat or carbohydrates, instead using protein, and he wondered if vampire bats would be similar.
But while hummingbirds and some nectar bats can fly, making experiments possible without large and expensive wind tunnels, vampire bats cannot. However, they have the ability to run at speedwhich they use to track prey on the ground so that Welch and Rossi can put their steps on tape.
Extracting most energy from amino acids is unusual in the animal kingdom, being limited to blood-feeding insects, emperor penguins during long fasts, and hibernating bears. “What’s different here is that this animal is going to be doing what it does year-round, when it’s feeding every day, and it’s using the protein from that blood meal that it just ingested a few minutes before,” Welch says. “That really sets these animals apart from most of the rest.”
Although most animals can convert nutrients into sugar and fat and store them, vampire bats have developed a different strategy because they are more vulnerable to starvation; in fact, they risk starvation after 24 hours without food, Welch says. To compensate for this, they have developed strong social bonds and will share meals when one member of the group has not found food, regurgitating some of their blood meal into another bat’s mouth to sustain it.
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