The ability to glide allows some creatures of the rainforest canopy to search for food over a wider range and escape from predators more effectively.
While only birds and bats can truly fly, several species of reptiles, some other mammals and a frog can glide from a higher to a lower place.
Animals that glide have a winglike membrane that, in its simplest form, may be only a fold of skin projecting from the side of the body.
Several mammals have this type of wing, or patagium, attached to the wrist and ankle. They use subdermal muscles to pull the wing away when it is not in use. When they are ready to glide, they relax these muscles and extend their limbs. This allows the membrane to spread completely.
Tail action, together with small movements of one or more limbs, provides the animal with directional stability.
The flight membrane of the flying frog is the webbing between the toes.
The flying snake has a more complex arrangement for gliding. These tree-dwelling reptiles do not possess a special membrane. Instead, they have the ability to pull in their ventral surfaces, flatten out their ribs and slightly rotate their scales to produce a concavity that traps a cushion of air beneath them as they glide.
These snakes steer by making lateral movements that resemble swimming. When the snakes "flight" ends, it makes a sudden upward flick of its head. This ensures a safe, smooth landing onto a tree or branch.
Flying dragons of the South Pacific islands have the most complex type of membrane. These lizards have a series of elongated, mobile ribs, covered with a tough skin, which project from the sides of their bodies.
When a flying dragon is feeding or resting, its wings are folded away. When it launches itself from a tall tree, strong muscle action extends the ribs and holds them rigid.
Many small muscles associated with the wing allow the flying dragon to change its trim during flight. This allows it to travel long distances and to perform complicated maneuvers, such as banking and rolling, in the air.