PORTLAND, OR. -- Rows of tiny crystals that armor the skeleton of a certain kind of starfish act as an array of microscopic lenses that would be difficult for even the best engineer to duplicate, researchers say.
The high optical quality of the microlenses in the brittlestar could help scientists design better computers or better telecommunications networks, according to scientists at Bell Labs in Murray Hill, New Jersey.
They identified the lenses after marine biologists noted the brittlestar appeared to be using the wrong kind of camouflage.
The creature would turn dark during the day, making it more visible to predators, and would turn whitish gray at night, again making it more noticeable.
"So it's just the opposite of what you expect to hide from predators," said Joanna Aizenberg, who led the study at Bell Labs.
Instead of trying to camouflage themselves, the brittlestars were using their microlenses as a sophisticated system to sense light in order to navigate and avoid predators.
The lens system turned the brittlestars lighter at night to increase their sensitivity. During the day, they turned darker to cope with the brighter light.
The shape of the crystals helped focus the light extremely precisely, Aizenberg said.
"We were quite surprised to observe that not only do they focus light, but the characteristics of these tiny lenses are far beyond anything we can imagine currently manufacturing," she said.
The unique spherical shape of the microscopic lenses may have applications for electronic and computer design, or may help produce superior optics that can adapt to changing conditions, she said.
Her study, which appears Thursday in the journal Nature, noted the calcium carbonate crystals -- or calcite -- also provide structural support for the brittlestar skeleton.
The lens design could prove especially useful for optical computers -- machines which use changes in light to store data instead of movement of electrons across a silicon wafer or circuit, according to another researcher. Light comes in packets of energy called photons.
"At some point we'd like to have optical computers, but to get to that point we have to move photons with the sophistication we now move electrons, and we aren't able to do it yet," said Sonke Johnsen, a biologist at the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts.
Johnsen said the latest research on the brittlestar's light-sensing ability helps explain why the creature can move so quickly to evade a threat, unlike other forms of starfish.
"They are really active, clever and fast animals," Johnsen said. "You'd have to work hard underwater to catch one."
