They think it could be used to lure prey or to ward off predators, but this remains unclear, they say.

The team still has not determined why the animals emit blue light or, even more broadly, why they produce light at all. However, since the worms do not produce riboflavin on their own, they must be acquiring their glowing properties from their diet or from symbiosis with bacteria, the researchers recently reported in the journal Photochemistry and Photobiology. In a separate experiment, the team found that riboflavin - also known as vitamin B2 - plays an important role in the worm's light production, but its exact role remains unclear. Now, Deheyn and his colleagues have conducted two new studies that help characterize it. Researchers have known about the unusual blue-glowing worm for decades, but nobody has ever looked closely at its light-emitting properties.

'If you produce light and you want light to be associated with an ecological function, you want organisms to see it.' 'Shallow water is much more complex than deep water from a physical standpoint, and green is what organisms see best,' Dimitri Deheyn, a biologist at the Scripps Institution of Oceanography involved in the research, told LiveScience's OurAmazingPlanet. Green light is more typical of shallow-water bioluminescence because it travels farther than any other color on the light spectrum, a useful quality in the turbid near-shore environment. Its glow sets it apart from other tube worms, most of which don't glow, and other shallow water organisms, which typically emit green light, not blue. The parchment tube worm can be found on shallow, sandy seafloors all around the world.

Download bioluminescent glow worms