Only some species glow – including a small sea snail found along the Australian eastern seashore.

Only some species of animals have the ability to glow (bioluminescence) – including a small sea snail found along the Australian eastern seashore.

The dazzling flashes of green light produced by this snail, Hinea brasiliana, have long puzzled marine biologists.

Now Dr Nerida Wilson, a marine researcher at the Australian Museum, and her co-researcher Dimitri Deheyn - working together at the Scripps Institution of Oceanography – have discovered how this snail uses its shell as a selective ‘lampshade’ to diffuse and amplify bright green light to make it look bigger and ward off predators.

“Bioluminescence is a common communication method in open water molluscs like squid, but is much rarer in marine snails that live on the bottom. One snail family has several members that can produce light; these are commonly known ‘clusterwinks’ because they group together in crevices at low tide on the rocky shore,” says Dr Wilson.

She collected the snails used in the study in Australia and collaborated with Deheyn to characterise the bioluminescence.

Hinea brasiliana produces light from two patches of cells on a part of its body that is always hidden underneath its shell. Discovering how the snail spreads its light surprised the researchers since this species of clusterwink features opaque, yellowish shells that would seem to stifle light diffusion. But when the snail produces green bioluminescence from its body, the shell acts as a mechanism to specifically disperse only that particular colour light.

Dr Wilson is now looking at other members of the Planaxidae family to see whether the snail's bioluminescent relatives also have shells matched to their wavelengths.

"I'm trying to create an evolutionary framework to test how these things have evolved. I'm very interested in whether there has been co-evolution between the shell and the bioluminescent system,” says Dr Wilson.

Proceedings of the Royal Society B ( Biological Science) - Bioluminescent signals spatially amplified by wavelength-specific diffusion through the shell of a marine snail Authors: Dimitri D. Deheyn and Nerida G. Wilson – 15 December, 2010