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Posts Tagged ‘dragonfly

Dragonflies – nature’s deadly drone – but beautiful

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Ruby Meadowhawk

African lions roar and strut and act the apex carnivore, but they’re lucky to catch 25 percent of the prey they pursue. Great white sharks have 300 slashing teeth and that ominous soundtrack, and still nearly half their hunts fail.

Dragonflies, by contrast, look dainty, glittery and fun, like a bubble bath or costume jewelry, and they’re often grouped with butterflies and ladybugs on the very short list of Insects People Like. Yet they are also voracious aerial predators, and new research suggests they may well be the most brutally effective hunters in the animal kingdom.

When setting off to feed on other flying insects, dragonflies manage to snatch their targets in midair more than 95 percent of the time, often wolfishly consuming the fresh meat on the spur without bothering to alight…

Next step: grab more food. Dragonflies may be bantam, but their appetite is bottomless. Stacey Combes, who studies the biomechanics of dragonfly flight at Harvard, once watched a laboratory dragonfly eat 30 flies in a row. “It would have happily kept eating,” she said, “if there had been more food available.”

In a string of recent papers, scientists have pinpointed key features of the dragonfly’s brain, eyes and wings that allow it to hunt so unerringly. One research team has determined that the nervous system of a dragonfly displays an almost human capacity for selective attention, able to focus on a single prey as it flies amid a cloud of similarly fluttering insects, just as a guest at a party can attend to a friend’s words while ignoring the background chatter.

Other researchers have identified a kind of master circuit of 16 neurons that connect the dragonfly’s brain to its flight motor center in the thorax. With the aid of that neuronal package, a dragonfly can track a moving target, calculate a trajectory to intercept that target and subtly adjust its path as needed…

…As a dragonfly closes in on a meal, it maintains an image of the moving prey on the same spot, the same compass point of its visual field. “The image of the prey is getting bigger, but if it’s always on the same spot of the retina, the dragonfly will intercept its target,” said Paloma T. Gonzalez-Bellido, an author of the new report…

Dragonflies are true visionaries. Their eyes are the largest and possibly the keenest in the insect world, a pair of giant spheres each built of some 30,000 pixel-like facets that together take up pretty much the entire head.

They have a full field of vision,” Dr. Robert Olberg said. “They can see you when they’re flying toward you and still see you when they’re flying away.”

RTFA. Lots of pertinent scientific information. Clinical description rendered fascinating by a unique subject.

The authors cover everything from sex to navigation, evolution to mechanics. Delightful read. Look forward to the whole report.

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Written by Ed Campbell

April 5, 2013 at 8:00 am

Three Gram ‘Dragonfly’ Takes Flight

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Engineers have made a new tiny DelFly Micro air vehicle. This successor to the DelFly I and II weighs barely 3 grams, and with its flapping wings is very similar to a dragonfly. Ultra-small, remote-controlled micro aircraft with cameras, such as this DelFly, may well be used in the future for observation flights in difficult-to-reach or dangerous areas.

The DelFly Micro is a ‘Micro Air Vehicle’, an exceptionally small remote-controlled aircraft with camera and image recognition software. The Micro, weighing just 3 grams and measuring 10 cm (wingtip to wingtip) is the considerably smaller successor to the successful DelFly I and DelFly II. The DelFly Micro, with its minuscule battery weighing just 1 gram, can fly for approximately three minutes and has a maximum speed of 5 m/s.

The ‘dragonfly’ has a tiny camera (about 0.5 grams) on board that transmits its signals to a ground station. With software developed by TU Delft itself, objects can then be recognised independently. The camera transmits TV quality images, and therefore allows the DelFly II to be operated from the computer. It can be manoeuvred using a joystick as if the operator was actually in the cockpit of the aircraft. The aim is to be able to do this with the DelFly Micro too.

Big Brother will be flying through your picnic – and you won’t even notice.

Written by Ed Campbell

July 23, 2008 at 10:00 am

Posted in Geek, Science, Technology

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