Flying and gliding animals

Several species of aquatic animals, and a few amphibians and reptiles have also evolved this gliding flight ability, typically as a means of evading predators.

In unpowered modes of locomotion, the animal uses aerodynamic forces exerted on the body due to wind or falling through the air.

Energy is continually lost to drag without being replaced, thus these methods of locomotion have limited range and duration.

[3] Powered flight uses muscles to generate aerodynamic force, which allows the animal to produce lift and thrust.

Ballooning and soaring are not powered by muscle, but rather by external aerodynamic sources of energy: the wind and rising thermals, respectively.

Soaring is typically only seen in species capable of powered flight, as it requires extremely large wings.

Many species will use multiple of these modes at various times; a hawk will use powered flight to rise, then soar on thermals, then descend via free-fall to catch its prey.

Although moving through the canopy running along the branches may be less energetically demanding, the faster transition between trees allows for greater foraging rates in a particular patch.

Larger animals need to glide from much higher heights and longer distances to make it energetically beneficial.

[9] Gliding is also very suitable for predator avoidance, allowing for controlled targeted landings to safer areas.

Worldwide, the distribution of gliding animals is uneven, as most inhabit rain forests in Southeast Asia.

The lower abundance of insect and small vertebrate prey for carnivorous animals (such as lizards) in Asian forests may be a factor.

Finally, insects (most of which fly at some point in their life cycle) have more species than all other animal groups combined.

The developmental origin of the insect wing remains in dispute, as does the purpose prior to true flight.

One suggestion is that wings initially evolved from tracheal gill structures and were used to catch the wind for small insects that live on the surface of the water, while another is that they evolved from paranotal lobes or leg structures and gradually progressed from parachuting, to gliding, to flight for originally arboreal insects.

These reptiles were close relatives of the dinosaurs, and reached enormous sizes, with some of the last forms being the largest flying animals ever to inhabit the Earth, having wingspans of over 9.1 m (30 ft).

Indeed, Archaeopteryx is arguably the most famous transitional fossil in the world, both due to its mix of reptilian and avian anatomy and the luck of being discovered only two years after Darwin's publication of On the Origin of Species.

[14][15] Bats are the most recent to evolve (about 60 million years ago), most likely from a fluttering ancestor,[16] though their poor fossil record has hindered more detailed study.

Gliding species are better able to control themselves mid-air, with the tail acting as a rudder, making it capable to pull off banking movements or U-turns during flight.

This has made the flight of organisms considerably harder to understand than that of vehicles, as it involves varying speeds, angles, orientations, areas, and flow patterns over the wings.