Bats are generally divided into two suborders: Megaptera (large Old World fruit bats) and Microptera (small bats found around the world). They vary in size, from giant flying foxes with wingspans up to 5 feet (1.5 meters) to bumblebee bats with wingspans of only 6 inches (15 centimeters). There are even three different species of vampire bats.
Bats are the only mammals capable of flying.
Like all real mammals, baby bats are nourished by their mother's milk. Bat cubs – usually only one, although some species can have up to three or four at a time. But no other mammal can fly like a bat. "Flying" squirrels and similar mammals glide at best. To make flight possible, bats digest food very quickly, sometimes within 30 to 60 minutes of eating. This helps them lose weight.
Bat droppings can be used to make gunpowder
Speaking of bat droppings, also known as guano, they have a high content of potassium nitrate (saltpeter) and are often used as fertilizer. Saltpeter can also be extracted for use in gunpowder and explosives, and bat guano was an important resource for this purpose during the American Civil War. Bat guano has also been found to preserve fossils.
Not all bats hang upside down
Almost all bat species hang upside down. Their feet have evolved to relax in a clenched position (hard for humans to imagine). When they're ready to fly, they let go and get power from the fall, because their calves and wings can't give them the kind of lift that their birds give. However, there are six species of bats that do not hang upside down. Most of these bats have suction cups on their limbs that allow them to stick to leaves or other surfaces.
Bats are not really blind
Only smaller bats use echolocation as their primary means of localization. Larger bats can see better than humans. However, vision is both a blessing and a curse because vision can overlay echolocation signals. For example, a bat might fly through a window because it sees light outside, even though echolocation tells it that the surface is solid.