A TWIST & A TERN: The river tern’s wings help it hunt (Photo: Getty Images and iStock)Which species evolved the ability to fly?

■ The animals which developed flying under power — which means they can stay up doing so — are birds, insects, bats and pterosaurs or relatives of dinosaurs. Many animals besides these can glide — there are fish that can glide in air, squirrels which glide between trees, etc. Aerodynamically, they are also flying but they cannot stay up. The only ones who can stay up as long as they want to have the power of flight — they flap their wings for this power.

NEAT! An Oriental White Eye shakes it up (Photo: Getty Images and iStock)

Why did these species develop flight?

■ We can’t pin it down to one reason but if you think about all the advantages you gain from flight, these include a lot. For an insect, for instance, flight gives the ability to reach and colonise new habitats you couldn’t get to by walking. After the eruption of the Mount St. Helens volcano in Washington state in 1980, the first animals to appear afterwards were insects — they could easily fly in and reach the area which was otherwise totally covered in ash. There are several advantages flight bestows, from foraging abilities — if you’re searching for food, you can see much farther and cover more area while flying — to escaping predators.

Flying is also an energetically economical way to move large distances — consider how a species might gain by moving from a temperate region to tropical lands seasonally. They cannot achieve this by walking but flying enables birds to migrate whenever needed. The longest terrestrial migration by foot is around 400 kilometres — a typical bird migration is thousands of kilometres.

A TWIST & A TERN: The river tern’s wings help it hunt (Photo: Getty Images and iStock)

What is the planetary timeline for the evolution of wings?

■ First, insects evolved flight in the Carboniferous era which occurred about 300 million years ago. Quite a while later, pterosaurs did so in the Jurassic era about 145 million years ago. Birds came not too long after — they were there in the Cretaceous era 100 million years ago. And bats evolved flight fairly soon after the dinosaurs vanished. Of course, bats have very fragile skeletons which matters in the fossil record. However, we know they were flying about 50 million years ago.

NEAT! An Oriental White Eye shakes it up (Photo: Getty Images and iStock)

What are fundamental operating principles of wings?

■ The basic work any wing must do is convert a forward movement into an upward force — this is true from a bumblebee to a jet airliner. By moving through the air due to its shape and the speed of moving, a wing produces an upward force. If you are a flying animal, the wing also has to produce a force that moves you forward — in an airplane, an engine separate from the wings moves the plane forward. As a bird or bee though, your wings must do both — this explains flapping. Airplanes don’t flap their wings because they have engines providing thrust to move ahead — flying animals produce thrust by flapping their wings. This moves them ahead and that move ment then lets them produce lift. So, in a sense, a bird wing is not fundamentally different from an airplane’s because they both have to produce lift — yet, they are very different because a bird wing has to produce both lift and thrust. In some ways, a bird wing is more like a helicopter or propeller rotor since these also produce lift and thrust simultaneously.

Are there similarities between the wings of an insect and a dinosaur?

■ Structurally, there are about as different as you can imagine — an insect wing is structured around a series of veins, not as in blood vessels but cylindrical structures. A very thin, almost microscopically thin, membrane stretches between these. An insect wing is one of the lightest physical structures in nature which is also weight-supporting.

A bird wing is built around a modified front leg — so, it has bones, muscles and skin. A bird wing also has feathers over most of its surface. A bat or pterosaur wing would have stretched skin over most of its surface, a framework of bone and muscles. So, these are all extremely different — yet, if you look at the flapping mechanism between, say, a dragonfly and a bird, the pattern is not that different. Physically, the wing of both must flap to produce thrust and lift. They do the same physical thing with a structure that could not be more different.

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Could you tell us about some fantastic wings you’ve come across?

■ An interesting one is the wing formed by the hind leg of a bird-like dinosaur called Microraptor — some palaeontolo gist colleagues of mine contacted me when they had these fossils. These dinosaurs were somewhat smaller than a cat and in the fossils we observed, there were long feathers on both their front and hind legs. We did tests to figure out how these feathered hind legs could work — we found they had operated as wings. It was basically a four-winged flyer.

Other remarkable examples includes the largest pterosaur named Quetzalcoatlus northropi. By scaling up the bones at hand, it was found its wing was longer than that of a small airplane. In addition, some birds have very elaborate feather arrangements on their wings, some trailing behind them like streamers, some using these for making sounds in courtship displays.

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Why should humans be more observant of winged creatures?

■ Engineers would say they have been around for millions of years and they may have solved major aerodynamic problems. Labs around the world are now essentially mimicking insect flight to build drones which can be used for surveillance, etc. Different labs are putting together essentially synthetic insects. A big area in aerodynamics now is ‘morphing wing’ technology — this means a wing that can smoothly change shape, in some cases, even changing its area. This is exactly what bird and bat wings do. A lot of research is going into the aerodynamics of this alteration in order to apply this to airplanes.

Birds and insects are also very important as they give us multiple services which we often don’t even realise — many eat mosquitos, for instance, which otherwise carry harmful diseases. Many flying insects are pollinators and produce food crops we need. So, when birds and insects start to disappear, we should be concerned. Their vanishing suggests something we are doing is impacting them adversely and while it may not be obvious, they provide us a great deal of benefits and services — aside from the fact that they are really cool.

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Magical moths

● Butterflies get rave reviews for their fabulous wings — but moths can easily outshine them. Outnumbering butterfly species 10 to 1, there are 1,60,000 known moths in the world. The Atlas moth is one of the largest lepidopterans or winged insects — found in tropical forests across Southeast Asia, its wingspan is 24 cms. It’s also called a ‘snake’s head’ owing to the cobra-like pattern on its wings, scaring off pesky predators.

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● The Luna moth is a superhero — it scatters bat sonar. The luna of north America sports pale-green wings which blend into foliage — it also has streaming tails that double its length. Bats hunt using sonar, making high-pitched squeaks, following the rebounding echoes of beating wings — but the luna’s tails produce echoes, confusing bats. Even when they find a luna, they go for the tail, with 96% attacks foiled.

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● The rosy maple moth is among the world’s prettiest insects — smallest among silk moths at just 4 cms, it is pink and yellow, its fuzz helping it pollinate better. Found in north America’s deciduous forests, it baffles scientists — its candy-like shades could be a warning about it possibly being poisonous or, less alarmingly, clever camouflage, allowing it to blend into flowers.

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Research: National Geographic, WWF, Smithsonian Magazine