This is how corals lure prey.
Scientists from Tel Aviv University may have been able to reveal the secret of why some deep-water corals glow in the dark. According to them, reef corals with glowing green and yellow tentacles fluoresce to lure prey, reports Science Alert.
Most of the corals that form reefs are in shallow water, so the algae that live in them can capture sunlight that seeps from the ocean surface. But there are other types of corals that grow at a depth of up to 6,000 meters in the dark and cold sea.
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< p>Researchers assumed that corals that live in such conditions can use light to attract prey. But they needed proof of this assumption, which they called the “light trap hypothesis”.
According to scientists, the ability to fluoresce and attract prey may be an important adaptation for corals living on the sea floor, especially those where corals require other sources of energy in addition to or instead of photosynthesis.
But there are other explanations for why corals can glow in the dark. For example, the “sunscreen” hypothesis suggests that fluorescence can protect bleached corals from further heat stress and light damage. Enhanced photosynthesis may be another possible explanation.
But mesophotic corals, which grow in low light with a blue shift, are a little different — there is no evidence yet that their fluorescence provides any protection or energy boost.
In the course of laboratory experiments, scientists wanted to find out which target small shrimp Artemia salina will 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 were really attracted to the fluorescent signal, they swam to it.
Similar results were obtained as a result of experiments conducted in the Bay of Eilat, located at the northern end of the Red Sea. In addition, the scientists compared the level of predation of Euphyllia paradivisa of different colors, which were collected in the Gulf of Eilat at a depth of 45 meters and brought back to the laboratory.
It turned out that fluorescent green corals are more likely to hunt predators than their yellow counterparts. fluorescent fellows, consuming more A. salina shrimp in 30 minutes. And when the experiment was repeated under red, not blue light, which does not excite the fluorescence of corals, there was no difference in the amount of shrimp consumed.
At the same time, the scientists note that only one type of coral was considered in their study. Additional research will be needed to understand how plankton and other crustaceans, which feed on corals, perceive color.
