The article, titled 11 Bloody Facts About Vampires, begins thusly:
Bats are firmly rooted in Western vampire lore, but only three species, out of some 1100 in the order Chiroptera, actually have a taste for blood. The vampire bats are the only mammals in the world that live on blood alone, and the unique challenges of that diet make them some of the most specialized, fascinating and downright weird animals that nature has to offer.
Of course, that's not what the article in mental_floss is about. Instead of repeating the article's information here, I encourage you to click on the link and read the 11 Bloody Facts for yourself. Then ask yourself, "What if Batman actually shared a bat's properties the way Spider-Man does a spider's?" The Batman story might be far darker and creepier with a vampire element.