Bats are important. A quarter of living species of mammals are bats--at least a quarter. I'm not sure how they would be in Joel's scheme of classification but in mine there are about 4,000 living species of mammals. Half of them are rodents and a quarter are bats. All the rest of the mammals make up the other quarter. Bats belong to the order Chiroptera. That's Greek for "hand wing". There are about 17 or 18 families of bats and an amazing diversity of species. You can't just think of a bat, there are so many kinds of bats. I'll introduce you to the variety of bats with a series of slides in a minute.