Winging It

One of the coolest things about bats is that they can fly. If you've ever seen a bat in person, you probably thought, "Wow – that looks like a mouse with wings." It turns out at least a few German folks would agree; the German word for bats is "Fledermäuse," which translates as "flying mice." Although many bat species do look a lot like flying rodents, in fact bats are more closely related to humans than they are to mice and rats. If you look closely at a bat's wings, you can see the resemblance.

A bat's wing is very much like a human arm and hand, except it has a thin membrane of skin (called the patagium) extending between the "hand" and the body, and between each finger bone. Bats can move the wing like a hand, essentially "swimming" through the air. The "thumb" extends out of the wing as a small claw, which bats use to climb up trees and other structures. This helps them reach a high "launching point" for flight takeoff. Appropriately, the order of bats is called Chiroptera, which is Greek for "hand-wing."

Scientists believe that bats evolved from a non-flying mammal that lived mostly in the trees, roughly a hundred million years ago. Like a lemur or squirrel, this animal would leap through the air from branch to branch. Some individual members of this species were born with more skin extending between their arms and body, which gave them just a little bit more lift as they leaped through the air (some modern lemurs and squirrels have developed this same sort of physiology). The individual bats with this mutation had slightly greater mobility than others in the species and so were more likely to thrive and reproduce. In this way, nature selected for wider and wider skin membranes over time, eventually leading to fully functional wings.

Bats can position their wings into different shapes, changing the degree and direction of lift very quickly. This lets them weave and dive in the air like no other animal, giving them a distinct advantage in hunting prey.

Free-tails, Ghosts and Bulldogs Besides providing mega-exterminator services by eating (up to several hundred) tons of crop-destroying insects, Mexican free-tailed bats are noted for two other extremes. First, their roosts are bat metropolises – with single-location populations numbering in the millions. Second, they're high-flyers. Bats from the well-known Bracken Cave roost in Texas have reportedly been seen soaring up to 15,000 feet. Ghost bats, which are among the false vampire bats, are large – some have wingspans of more than 22 inches. Their pale fur inspired the ethereal moniker. More impressive than their actual size is their appetite. These carnivores are known to eat dozens of species of birds as well as mice and large lizards. Some of their prey is as much as 80 percent of the bat's own weight! Some bats are avid anglers. For example, the greater bulldog bat, also known as the fisherman bat, spends much of its time foraging for fish. Using echolocation to track its prey, the bat swoops down to the water's surface and hooks the fish with its hind legs. The meal starts mid-flight, and two large cheek pouches store this partially chewed prey for later so that the bulldog bat can carry on with its fishing expedition.