Lights ... camera ... penguins!

Marshall, 49, is the brains behind Crittercam, an invention he has been using for 20 years in research he's done as a National Geographic Society marine biologist.

"Almost every Crittercam deployment is something exciting, unusual and new," he said from his office in Washington, D.C. "We truly do not know what these animals are doing out there; they live in a world we have no access to. So this is the first opportunity we have to observe them on their time scales and their world."

Marshall will share his Crittercam adventures with an audience when he returns Thursday to his native Minneapolis to be the first speaker in the four-part, once-a-month series called "National Geographic Live!" at the State Theatre.

You've seen Marshall's Crittercam in action as part of the Oscar-winning 2005 film "March of the Penguins" or any of many National Geographic TV specials he's worked on, including two Emmy winners.

For "March of the Penguins," Marshall's penguin-powered underwater footage -- done under the auspices of a separate research project with the Scripps Institute of Oceanography -- was augmented with topside footage shot by the film's French makers. A documentary on the film's DVD offers a behind-the-scenes look at his work.

Marshall was a grad student in 1985 when he came up with the idea for Crittercam. In Belize, he was filming a shark underwater when he noticed a remora, a suckerfish, attached to its larger host. If he could make a camera small enough and streamline it, he thought, the device could be attached to the silent predator like a remora, providing a fish's-eye view of "how that shark's life unfolds through that alien space known as the ocean."

"As I was scuba-diving on that particular day, this idea occurred to me, and I've been trying to make it happen ever since," Marshall said.

"It acted, as far as I can tell, normally, even with this fairly large instrument on its back," Marshall said. "It's that critical insight that allowed this program to move forward at all."

His tinkering and advancements in audio-video technology have led to significant modifications to Crittercam over the years. The latest version weighs barely more than a pound and is about 10 times smaller than the original.

Although it's difficult to put a price on Crittercam because it's part of an entire research and development program, individual models have been insured for $7,000 to $13,000. The soon-to-debut next-generation device will be easier to use and can be mass-produced at a replacement cost of only $2,000.

"It is really going to change the way we are able to contribute to science in a significant way," Marshall said.

He even has come up with noninvasive ways to attach Crittercams to animals. For penguins, it's easy: The gentle, naturally curious creatures simply waddle up to a researcher, who slips the camera pack on its back and sends the bird on its merry way like a tuxedoed kid going off to school. Shark Crittercams have a clamp with a sandpaper grip to keep them affixed to the dorsal fin, while the devices for whales and turtles use suction cups. But Marshall hasn't found a better way than sedation to attach Crittercams to land animals such as lions.

All of the data and video -- eight hours now, but progressively longer once the next-gen models enter the field -- are stored directly on the devices. That means Marshall and his team have to recover each Crittercam. For ocean deployments, they are aided by a radio signal that starts transmitting after the microprocessor releases the Crittercam from the animal and the device floats to the surface.

Amazingly, he said, only about 4 percent of Crittercams have been lost in more than 20 years.

So, when will a Crittercam be available for pet owners to use with Fido or Fifi?

"We definitely need to do a Petcam," Marshall said. "While I think there's a real interest in it, the challenge is that we've been so focused on the research and scientific applications of this tool that we really haven't spent the time developing the technology associated with a Petcam."

He added with a laugh, "The funny thing is that it could probably fund my entire research program."

"Ultimately, we do all this because we want to change the world for good," he said. "We want people to become aware of what these animals are doing out there so we can understand what their fundamental needs are. By virtue of that understanding, we can come to care about the animals and invest in sustaining those needs."

Randy A. Salas • 612-673-4542