Video transcription

Hello I'm Dr. Christine Portfors. I'm an associate professor in the school of biological sciences at Washington State University Vancouver. And today we're here to talk about where do vampire bats live. And yes, there are actually vampire bats. There's three different types of vampire bats and they all live in Central and South America. So the three different species are very, very interesting. They have evolved to survive strictly by drinking blood, two of the species drink blood of birds and one of the species drinks blood of mammals. They don't have to eat anything else and they also don't have to drink water, they get all the nutrients they need from the blood of the animal. So many of you might be thinking whoa that's pretty gross, but in fact it's a very interesting system. So the vampire bats have evolved to be able to seek out blood. And so the way that they do this is that they use their echo location system, which means they're sending out high frequencies of sound and listening to the echoes coming back to fly around and for example find a cow. And then what they do is they can crawl on the ground really, really well, it's one of the few bat species that can be down on the ground and crawl, and they find their animal of interest, they crawl up on the leg and then they have special heat sensor mechanisms around their face that locates the close proximity of a blood vessel. And then what they do is they have very, very sharp incisor teeth, like razor blades, and they make a very small slit in the skin that allows the blood to come out. And then they've got a forked tongue, well it's sort of forked, but kind of like a triangle, and they just sit and they lap up the blood just like your cat or dog does when it's drinking some water. But what's interesting is that the bat's saliva has two properties in it. One is that it has an anticoagulant which means when the blood is flowing from the animal it doesn't scab up so that this anticoagulant goes into the blood vessel, into the blood of the animal and allows the blood to flow so that the bat can continue to drain. And it also, the saliva also has an analgesic effect so that the cow or the goat or the bird doesn't feel the bat on it and actually drinking some blood. And then as soon as the bat's finished, then the anticoagulant goes away and the wound heals up. Now the vampire bat only drinks about a teaspoon to maybe a tablespoon of blood every time it feeds. So it's not very much so the animal does not die. So many of you might be asking well if the vampire bats drink blood from mammals, will they drink blood from a human? And yes they can and that just means that if you happen to be in Central or South America and you're out sleeping at night, you don't want to have your toes exposed or your fingers exposed because the vampire bats can actually come down and drink blood from you. But vampire bats they have a very bad press because of Hollywood and Dracula turns into a vampire bat, that obviously is not true but it is true that there are vampire bats. And the vampire bats are doing very, very well in the tropics because a lot of agricultural animals are being introduced. The forests are being cut down and agricultural animals are coming in so that the bats have a lot of food right there so that they've got plenty of opportunity to have lots of food sources which means that then they have lots of young, lots of babies and the populations can grow. Vampire bats are also very interesting because they have a very cool social organization where they in their roosting site, there's a lot of them that roost together and when they come back after feeding, if one vampire bat hasn't fed, other bats will regurgitate blood for them so that that animal actually has something to eat that day. And it doesn't always regurgitate to a member of it's own family, it's just a member within it's roost so that they all work together for survival of the roost or the colony itself. So they're very interesting animals and if you ever get a chance to see one at a zoo, take a look at them, they're really cool. Oh and also they're only about, their body's only about this big and their wings are maybe like this so they're not huge bats, they're not scary at all, they're actually very cool from an evolutionary perspective.