Tel Aviv University scientists may have solved the mystery of why some deep-sea corals glow in the dark. Reef corals with glowing green and yellow tentacles fluoresce to lure prey, they say..

Most of the corals that form reefs are in shallow water, so the algae that live in them can capture the sunlight that seeps in from the surface of the ocean.. But there are other types of corals that grow up to 6,000 meters deep in the dark and cold sea..

[see_also ids\u003d"

The researchers speculated that corals that live in such conditions could use light to attract prey.. But they needed evidence for this assumption, which they called the “light trap hypothesis.”.

The ability to fluoresce and attract prey could be an important adaptation for seafloor corals, especially where corals require other sources of energy in addition to or instead of photosynthesis, scientists say..

But there are other explanations for why corals can glow in the dark.. For example, the " Increased photosynthesis could be another possible explanation.

But mesophotic corals that grow in blueshift low light are a bit different—so far there is no evidence that their fluorescence provides any kind of protection or energy boost..

During laboratory experiments, scientists wanted to find out which target the small Artemia salina shrimp would swim to: green or orange fluorescent or transparent, reflective or matte, located at the other end of the aquarium. It turned out that the shrimp are indeed attracted to the fluorescent signal, they swam towards it..

Similar results were obtained as a result of experiments carried out in the Gulf of Eilat, located at the northern tip of the Red Sea.. In addition, the scientists compared the levels of predation of Euphyllia paradivisa of different colors, which were collected in the Gulf of Eilat at a depth of 45 meters and taken back to the laboratory..

It turned out that fluorescent green corals prey on predators more often than their yellow-fluorescent counterparts, devouring more shrimp A. salina in 30 minutes. And when the experiment was repeated under red instead of blue light, which does not excite coral fluorescence, there was no difference in the amount of shrimp consumed..

However, scientists note that in their study, only one type of coral was considered.. More research will be needed to understand how plankton and other crustaceans that corals feed on perceive color..