Glowing dinoflagellate plankton blooms make some of the most beautiful visions in nature. While feasting their eyes on some of the remarkable spectacles biologists have been perplexed about why they do it. For “the worlds largest” studied of the many bioluminescent plankton species, the brief flashes of light deter grazers that would otherwise eat them.
Animals such as fireflies use the capacity to glow in the dark to attract mates, while others use it to attract their prey. Neither of these applies to the single-celled creatures that can turn night-time seas into shimmering fields of blue-blooded. Yet there has to be some evolutionary advantage. Producing so much light requires a lot of energy, and for creatures that can’t run away, it is risky to notify grazers to their presence.
Andrew Prevett of the University of Gothenburg studied the interactions of Lingulodinium polyedra and the copepods that feed on them applying high-speed, low-light-sensitive videos. He reports in Current Biology that when L. polyedra feels the fact that there are a copepod( a kind of small-minded crustacean) it makes off a flash of blue-green light lasting around a one-tenth of two seconds. This causes the copepod to stop sweeping the dinoflagellate towards its mouth and allows the prey to escape while the copepod strives non-bioluminescent prey.
L. polyedra grow at simply a third of the rate of diatoms, another form of plankton that inhabit the same waters, presumably because developing and applying bioluminescent capacities get in accordance with procedures of interesting thing. In most circumstances this leads to < em> L. polyedra being being replaced by species capable of faster growth. Off the west coast of Sweden, nonetheless, the exception is copepod-rich water. Presumably, the smaller crustaceans deter competitive plankton amounts down, offering space for their sparkly cousins.
“There are three popular theories as to how bioluminescence protects dinoflagellates, ” Prevett said in a statement. If the dinoflagellate grows toxins light can be a way of alerting grazers this is something they don’t want to eat. The sudden twinkling may also startle the grazer and disorientate it enough to allow the dinoflagellate to escape.
“The third hypothesi therefore seems that the burst acts as a sort of burglar alarm, attracting the attention of a larger visual piranha, like a fish, which could track and devour the copepod, ” Prevett added. “There is evidence to support each of these beliefs and bioluminescence safety could be combinations of some or all of the above.”
The advantages may vary by species and the grazers that feed on them. Not all L. polyedra are bioluminescent and Prevett’s copepods were read to feed merrily on non-glowing < em> L. polyedra , which adapts inadequately with the first explanation.