Voice of DANIEL STREICKER, PhD, UNIVERSITY OF GLASGOW & NATIONAL GEOGRAPHIC GRANTEE:

Here we are seeing the vampire bat displaying how it really laps blood out of the animals that it is feeding on. You can see some key features like how the tongue has these cool grooves that allow the blood to flow back. The tongue also excretes an anticoagulant which really keeps the blood from flowing.

So the way the vampire bat feeds is not by sucking blood through its big canine teeth, but rather making a small divot to the flesh of the animal and then lapping it up with its tongue. And their teeth is so tiny and sharp that you barely feel it. It's like a needle prick.

Vampire bats often wait to forage until the night is completely dark. So that is often after the moon has disappeared from the sky. You can see these bats are really good flyers but also incredible good on the ground. This is a really rare trait for a bat species to be able to walk on the ground, even hop and run. And this provides a really nice way for the bats to avoid getting squashed or getting captured by the animals they are trying to feed on. You can see they are really stealthy, stalking up to the animals as well as hopping around. And while the bat is doing that, part of what it may be doing is finding the right place to bite. So it could either hop up to the animal or it can fly directly on to the animals landing, often in the case of a cow, it will land on the back.

The bat will then use some infrared sensors, basically trying to find the part of the animal where the blood is flowing most closely to the skin. And that is the site it will use to make that initial bite wound and then lap up the blood.

Cows obviously feel that bat landing and even try to get the bat off of them, but eventually the cow gives up and the bats are able to return to the spot where they wanted to eat. At least it is not bothered enough that it continues to struggle against the bat.

There is something a little bit creepy about a mammal that lives exclusively on blood. And a lot of the behaviors that you see in a vampire bat, things like creeping around, and having that really long tongue and triangular teeth, all that fits into the Dracula/Vampire stereotype. So it is in some ways a fair characterization, but it's also important to know that these are totally fascinating animals that are completely and perfectly adapted to their lifestyle of feed just on blood.