A marine snail has a shell that is remarkably well adapted for diffusing the light that it emits to ward off predators.

Stimulating Hinea brasiliana snails (pictured), by tapping them or placing them in contact with potential predators, causes them to emit a blue-green light from defined areas of their body, report Dimitri Deheyn and Nerida Wilson of the Scripps Institution of Oceanography in San Diego, California. The shell directly transmits most wavelengths of light, with the exception of blue-green ones. These are instead spread by the shell from the limited production regions of the snail's body over a much larger area (right).

The shell produced brighter and larger areas of diffused light than a commercial diffuser. Such shells allow snails to produce visible and extensive bioluminescent signals from their protected position inside the shell.

Credit: R. SOC.

Proc. R. Soc. B doi:10.1098/rspb.2010.2203 (2010)