When it comes to technologies that only humans can use, you might think fiber optics is among them. However, this is obviously not the case. Scientists have discovered that there is a clam that uses its own "optical fibers" to obtain food. The heart-shaped clam, named for its heart-shaped shell, is a marine clam native to the Indo-Pacific region.
In addition to filtering plankton from the water, this mollusk feeds on sugars produced by algae living in its soft tissues. The algae produce these sugars through photosynthesis, which requires sunlight...and there's usually not a lot of sunlight deep inside a sealed clam shell.
While clams can give the algae some light by periodically opening their shells, doing so leaves their delicate innards vulnerable to predators. Instead, they evolved translucent windows that form a series of small bumps on the shell. In a recent study, scientists at Duke and Stanford University examined these windows using electron and laser microscopy.
The study found that beneath each window, which acts as a lens for focusing sunlight, the layered calcium carbonate sheets that make up the shell form tight, hair-like bundles of fibers. Regular plates run lengthwise through the shell, like stacked bricks in a brick wall, while fibers run perpendicular to them, running through the shell's thickness.
The fibers not only channel sunlight from the surface of the shell down into the algae, they also filter out parts of the ultraviolet rays that could be harmful to the clams, while allowing the blue and red light needed for algae photosynthesis to pass through.
Professor Sönke Johnsen of Duke University co-led the research with Dakota McCoy, a postdoctoral researcher at Stanford University.
A paper on the research was recently published in the journal Nature Communications.