英语听力：自然百科 Vampire Bats 恐怖的吸血蝙蝠

Here are some happy vampire bats. What's causing all this giddiness? A great, big, fat meal has arrived. You can practically hear these bats going "Oh, boy! Oh, boy!" Better yet, the victim is asleep. This is gonna be like, well, taking blood from a sleeping pig.

The bats have heat sensors in their noses. This thermal process lets us see what the bat sees. The bat wants to feed where the pig's skin glows white hot. Let the dining commence. Like two wildcatters fighting over a fresh oil strike, these bats battle over a particularly rich feeding spot. Four vampire bats, one sleeping pig. Why doesn't the pig wake up? Because the bat's teeth are razor-sharp and cut painlessly. The bats can sip to their hearts' content with the pig none the wiser. The bat's saliva actually prevents the blood from clotting. As the bat sips, the blood runs up a glue on the underside of its tongue. Mother Nature thinks out everything. These vampire bats can feast for a full half hour, drinking half their weight in blood.

In a month of feedings, five vampire bats can guzzle almost a gallon of pig's blood. In this case, it's the bats making a pig of themselves, not the pig.