Meet Eric - an Indian Fruit Bat. Like most bats, he likes to spend most of his time hanging around upside down, but why?

Hanging around for humans isn't very practical - as Kate found out! You've probably felt it yourself whenever you've been hanging around. All the blood rushes to your head and it feels like it's about to explode!

But bats aren't bothered by that. So why do they choose to hang from a tree, rather than build a nest?

Well, imagine that this jar full of straws is a colony of bats. If the straws are all upright they take up much less room...

...than being spread out like this.

And it's the same with bats. When Eric is spread out on the floor he takes up much more room than when he is hanging upside down from the ceiling.

As bats live in massive colonies, roosting space is precious. So, hanging upside down is a great idea. And there's not much competition for ceiling space from other creatures.

Hanging from the ceiling is also a good idea because they can stay away from their enemies.

Kate is very uncomfortable - she has to concentrate on staying on. If she relaxes or falls asleep, she'll fall off!

Bats don't have to worry about that thanks to a special mechanism on their toes. They simply hook on and their body weight locks the mechanism so it won't fall on.

A bat can stay upside down with almost no effort whatsoever - unlike Kate. Even a dead bat continues to hang on!

But there are two problems with living upside down - reproduction and excretion (or having babies and pooing). Bats hoist themselves up to have their babies and they catch them with their wings. They also hoist themselves up to go for a poo.

There is one advantage to life upside down. A bat has to put in a lot of work to take off from the ground, but living life upside down means launch efficiency!

The bat simply lets go, opens wings, and is instantly flying!

Eureka! So if you're a bat, upside down is pretty much the right way up.

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