It's not just birds and bats which take to the air - other animals manage it too.
The ability to glide was probably developed by cliff-living or tree-living creatures to escape from enemies, or as a labour-saving way to get from one tree to another.
The flying dragon of Southeast Asia (actually a lizard 150 millimetres long) has a web of skin on either side of it's body, attached to movable ribs which can be opened and closed like a fan.
It can glide up to seven metres after launching itself from a tree. Some flying squirrels can soar more than 100 metres. A tree frog from Malaysia, and another from Costa Rica, have developed extra-large feet, the membranes between the elongated toes turn each foot into a parachute so that it can leap - feet spread-eagled - from tree to tree. The small Panadeso tree snake of Borneo broadens its body and bends it into a series of curves, enabling it to bank and float its way through the air for 20 metres.
Flying fish wag their tails from side to side as they leave the water, then spread their fins to catch the air currents which may lift them six metres high.
They can glide up to 400 metres and reach speeds of 64 km/h.
