Today’s Wonder of the Day was inspired by Jorge from Vista, CA. Jorge Wonders, “What's the difference between a bird and a bat?” Thanks for WONDERing with us, Jorge!

We were walking through the Wonderopolis forest the other day when we overheard an interesting conversation between a badger and a rabbit:

Badger: Say, Roger, what's that way up high in the sky over there?

Rabbit: You mean by the bridge over the pond, Bruce? I think it's an airplane.

Badger: An airplane? I don't think so. I thought it was a bird. Oh look! Here it comes!

Rabbit: Yikes! That's not a bird. It's a bat!

Badger: A bat? It's flying, so I guess it's a bird after all.

Rabbit: Is it?

Badger: Isn't it?

If you think about it, it's understandable why the rabbit and the badger were confused. Bats obviously fly through the air. But does that make them birds?

Even though they fly through the air, bats are not birds. People used to think of bats as birds without feathers. According to scientific principles of classification, though, we now know there's no such thing as a bird without feathers. Instead, bats are mammals.

In fact, bats are the only mammals that can truly fly. A few other mammals, such as the flying squirrel, appear to fly, but they actually glide through the air instead.

What makes a bat a mammal? For starters, it has fur instead of feathers. Bats also give birth to live young and produce milk to nurse their babies. Birds, on the other hand, lay eggs and feed their young with food they find by foraging. Birds have beaks and no teeth, whereas bats have jaw bones with sharp teeth.

Although they both fly, birds and bats feature different structures that allow them to take flight. Birds have rigid, feathered wings that they flap completely in order to fly. Most birds have wings that can only move in a couple of directions.

The wings of bats consist of highly-flexible membranes stretched between their elongated fingers. Although birds and bats have the same types of bones in their wings, the bones in a bat's wing more closely resemble those in a human hand. With more than two dozen joints in their wings, bats can exercise a great deal of control over the three-dimensional shape their wings take.

This unique feature of their wings allows bats to fly more efficiently than birds. Scientists have long known that bats use less energy than birds when they fly. They just weren't sure why this was the case. Further tests have shown that bats are able to manipulate their flexible, jointed wings during flight to maximize lift and minimize drag, thereby using less energy and improving maneuverability.

Wonder What's Next?

Grab a stick! Tomorrow’s Wonder of the Day takes a beating and keeps on treating!