High-Speed Videos: The Hidden World of Insect Flight
- 7:00 am |
Using high-speed video cameras that capture more than a thousand frames per second, Andrew Mountcastle's videos reveal an insect ballet hidden to plain sight.
"I refer to high-speed cameras as time microscopes. You see things that you can't see with your naked eye," says the Harvard University biologist, who specializes in the flight dynamics of moths.
While a Ph.D. student at the University of Washington, Mountcastle and labmate Armin Hinterwirth were commissioned to replace the Pacific Science Center's outdated video installation. The pair filmed garden-variety insects in flight, their everyday glory unmasked in slow motion.
"What's commonplace in the life of these insects is new and exciting. That's the really neat thing about high-speed cameras," said Mountcastle. "You can point them in any direction, and before long you're capturing something interesting."
Mountcastle took Wired.com on a tour of his work.
A bumblebee launches itself from a bloom.
"A lot of the filming we do starts with focusing on an insect on a perch, so we can get our aperture and frame rate just right. I was trying to get the takeoff sequence," said Mountcastle. "I had no idea there was a frog camped underneath the perch. When the event happened, I wasn't even looking at the dragonfly. Something else caught my attention. I heard this splash in the water and turned back. My dragonfly was gone and there were ripples in the water."
"In one sense, it's funny to watch he ladybug not successfully take off. But you wonder, how often does this happen?" said Mountcastle. "Takeoffs and landings happen so many times a day, it's not surprising that sometimes it doesn't work out quite so well."
"What you can see clearly is that they have two sets of wings. The forewing, or elytra, is what you're used to seeing when they crawl around. It's a protective wing. What drives flight is the hind wings, which are intricately folded and protected by the forewings," said Mountcastle. "Most people have assumed that these elytra don't serve much purpose in ladybug flight. But to my knowledge, nobody has actually explored the role of forewings in flight. It's easy to look at them and say, evolution has driven them to be first and foremost protective, but there might be implications for flight that have gone unnoticed."
"There's something about capturing an insect in midair during flight that's just so exciting," said Mountcastle. "Even if it does something that's entirely mundane to the insect, viewing their flight with the high-speed camera gives you a glimpse into a world that operates on a much faster time scale than we're adjusted to seeing."
"It makes you wonder, how often does this happen? It might be totally normal, it might not be. We don't know," said Mountcastle. "You get the sense that this kind of thing happens more often than not. In a given plant, it probably happens many times in a day, and yet we never see it."
"The katydid has a very quick takeoff. It has different control challenges than other insects. It's tempting to see its takeoff as a haphazard, less-controlled launch. But at the same time, it works for this particular organism. It's been around for millions of years, so it's doing something right," said Mountcastle. "It certainly looks a bit uncontrolled on takeoff, but then you see it start to recover as it leaves the frame. That gives the impression that it's able to regain flight control pretty quickly, which is impressive in its own right."
Frog Fail 2
From another perspective, of course, the frog's fail is the dragonfly's success. "It's a really nice illustration of the importance of having a fast escape response. Dragonflies have great vision that's really important not only for capturing prey, but escaping predators."
Unlike the other videos, this comes from Mountcastle's academic work on Manduca moths, in particular the aerodynamic consequences of their wings' ripples and folds.
"They are relatively large moths, not quite as big as hummingbirds, but approaching that size. They've got this long, tongue-like proboscis, which they unroll and stick into flowers to feed on the nectar. They need to be very good at hovering," he said.
"If there's a breeze, if their food source is blowing around, they track it while hovering. And as you can see in that video, their wings bend and twist quite a bit, When I started five years ago, we knew that insect wings deformed, but we knew very little about the aerodynamic consequences of these deformations."
While many biomechanicists work towards potential industrial or engineering applications, Mountcastle's great motivation is curiosity.
"In insects, we see a staggering diversity of shapes and sizes, and a huge diversity of wing shape and size and function," he said. "Why has evolution given us so many forms? Understanding that is what motivates me."
Video: Andrew Mountcastle
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