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Tiny critter becomes a big wheel

Charles Krebs

The first-place winner in this year's Olympus BioScapes competition shows a rotifer (Floscularia ringens) feeding. Its rapidly beating hairlike structures, known as cilia, bring in water that contains food for the rotifer. Click on the image to see the top 10 Olympus BioScapes entries.

Rotifers have been the big wheels of the microscopic world for more than 300 years, so it's fitting that a rotifer's wheel-like head gets its turn in the photographic spotlight.

An extreme close-up of a type of rotifer known as Floscularia ringens has won first prize in the 2011 Olympus BioScapes Digital Imaging Competition, which showcases photos and movies of life science subjects. The image was the top selection out of more than 2,000 entries in this year's contest — and it earned the photographer, Charles Krebs, $5,000 worth of Olympus imaging equipment.

"I've always gravitated toward abstract small things that people don't normally look at," Krebs told me last week as he prepared to pick up his prize at a Washington ceremony. "So the microscope takes that to another level."

Prize-winner in a pond
Krebs has been doing photography for decades from a home base in the "other Washington": a suburb of Seattle called Issaquah. He's been focusing on photomicrography — the creation of images using a microscope — since 2004, and in that time he's become one of the leaders in the field. Most of the contests for microscope-made images feature one of Krebs' pictures as a finalist.

"The camera that I use is a Canon digital SLR camera, which many researchers do not use," Krebs said. His lab, which is a converted darkroom, is outfitted with a complement of Olympus microscopes and optics. "But it's not the latest and the greatest," he said. "It's about 20 years old. The latest and the greatest is a little out of my price range." (State-of-the-art, professional-grade microscopic imaging systems can cost tens of thousands of dollars.)

Krebs' prize-winning subject came from a pond near his house. "This is a particular type of rotifer that I've always found fascinating to watch," he said. "One of the most striking things to me is the little domicile, the tube that it builds. Each individual 'brick,' if you will, is made by the rotifer."

In the picture, you can see a "brick" inside the rotifer's semi-transparent body, about to be added to the tube-shaped matrix at the bottom.

Even more striking are the "ears" of a rotifer. These structures, which measure 300 microns or 0.012 inch from one edge to the other, make up the marine animal's corona. Tiny hairs on the corona, known as cilia, sweep at lightning speed to direct water containing bits of food into the rotifer's mouth. "When you see this in life, those things are moving so fast that they look like two little wheels on top," Krebs said.

Wheel animalcules
That activity is what earned the critter its name: "Rotifer" comes from the Latin words for "wheel-bearing." When Anton von Leeuwenhoek, the Dutch tradesman known as the father of microbiology, looked at rotifers through one of the world's first microscopes in 1703, he called them "wheel animalcules." Some rotifers are just big enough to be seen with the unaided eye. One common type, the bdelloid rotifer, has been reproducing for 40 million years without sex

Rotifers play a key role in filtering out the decomposing organic matter contained in water. And those rotifers, in turn, make nice snacks for fish, shrimp and crabs. A single drop of pond water might contain 50 to 100 rotifers.

A video from EDF Williams shows a rotifer feeding.

Although it's easy for Krebs to get his little critters, it's not so easy to capture a great picture of them. Krebs used a complex lighting scheme known as differential interference contrast illumination to bring out the fine details of the rotifer's structure. An electronic flash was used to freeze the rotifer's motion.

"After I took the shot, I knew it was probably one of the nicest headshots of this particular animal that I had," he said. "You may look at 100 different specimens, and they're just not at the right angle, or they stick their head out and there's a big blade of grass covering it."

Krebs does a lot of other photographic work, including product shots. "There's a fair number of companies that need photographs of very small things," he explained. But tiny critters like the prize-winning rotifer rank among his favorite subjects.

"I'm not a scientist," he said. "I'm not a zoologist, I'm not a biologist. But it's always been an interest of mine."

To see more of Krebs' work, check out his website as well as his favorite hangout on Photomacrography.net. And while you're at it, take a spin through these galleries on msnbc.com:

Correction for 2:55 p.m. ET Nov. 15: In one of the more humorous mistakes I've made lately, I misheard Krebs' reference to a blade of grass as a "plate of glass." I've corrected the quote.

Images from the 2011 Olympus BioScapes Digital Imaging Competition will go on a national museum tour. For additional information, hvisit the Olympus Bioscapes website

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