A rather common marine creature with an unusual ability, the parchment tube worm (Chaetopterus variopedatus) secretes a mucus that glows blue. The worm is named for its habit of forming paper-like cylindrical tubes around itself and inhabits shallow coastal waters in temperate and tropical climates.
The bioluminescence of the parchment tube worm is uncommon for several reasons. For one, most other species of tube worms have no form of bioluminescence at all. In addition, the striking blue color of the slime is itself a rarity. The reason that green bioluminescence is more common is because of the frequency of green light, which is longer than that of blue and purple light and will therefore travel farther through water.
Although the bioluminescence of the parchment tube worms is not a new discovery, scientists with the Scripps Institute of Oceanography at UC San Diego and Connecticut College have decided to reopen the case after a 50 year dormancy in order to learn more. One scientist, Dimitri Deheyn, has determined that the glow is made possible by a specific “photoprotein” that does not require oxygen to function, a noteworthy characteristic as bioluminescence normally occurs when two chemicals react in the presence of oxygen.
Scientists are unsure of the practical function of the mucus, but say it is likely either a way to attract prey or to ward off potential invaders of the worm’s home (“the glowing mucus could stick to an intruder, making it more visible to its own predators”). Another theory is that the mucus somehow plays a role in the formation of the worm’s tubes. However, the blue color remains a mystery.
In another plot twist, the strange bioluminescence seems also to depend on vitamin B12, or riboflavin, yet it cannot be synthesized by the worm itself. Researchers have come to believe that the worms must either be consuming the riboflavin or obtaining it through a symbiotic relationship with bacteria that is able to synthesize it.