Navy Models Fish-Like Sub After the Real Thing

The tiny box fish looks like a cartoon character with its peculiar shoe box shape and bright yellow body with black spots. It lives in a rigid shell, unable to bend its body because its scales are fused together.

It seems an unlikely candidate for military research, but this tiny wonder is the very model the U.S. Navy hopes to use to design a new miniature submarine that will scour the ocean bottom, operating efficiently even in turbulent waters.

The sub could have myriad uses, from combing for underwater mines to conducting scientific research or hunting for wreckage from airplane crashes.

“Fish are phenomenally maneuverable compared to anything that is man-made,” said Jeff Walker, a biology professor at the University of Southern Maine who is studying the box fish to better understand how it swims and moves its body.

“It’s a lofty goal for a human-made vehicle to achieve the performance of a fish.”

The Office of Naval Research awarded Walker a three-year, $90,000 grant to work with a team of engineers on the project. The Naval Undersea Warfare Center in Newport, R.I., will be in charge of designing the sub, also known as an “autonomous underwater vehicle,” or AUV.

The AUV should be able to remain stable while working in waters shallower than 1,000 meters, said Robert Gisiner, who is overseeing the project at the Office of Naval Research. Existing AUVs, he said, are not good at handling underwater currents greater than 1 knot.

“What we’re interested in creating is an underwater [machine] that has the abilities of a biological organism that you can’t get in standard structures now,” Gisiner said.

The box fish is related to the better-known puffer fish and lives primarily in tropical waters around coral reefs in the Pacific Ocean.

Working in a cramped laboratory at the University of Southern Maine, Walker is studying three juvenile box fish that he has named King Kong, Nessie and Jaws. A high-speed digital camera records their activities and downloads the images onto a computer, where the movements and speed can be precisely measured.

The box fish is no bigger than a couple of matchboxes stacked one atop the other. But it is a perfect research specimen because it is so maneuverable and can turn on a dime, almost like it is rotating on an axis.

Box fish fins look like folding fans and act as paddles. By paddling one of its pectoral fins forward and the other backward, the fish can make a 360-degree turn with barely any movement--just like a person in a stationary rowboat paddling the oars in different directions to turn around.