Scientists Discovered The Reason Why Deep-Sea Corals Glow

Corals fluorescing green and yellow
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Corals fluorescing green and yellow

Highlights

  • A group of Israeli scientists has now determined why that might be the case.
  • Coral reef researcher Or Ben-Zvi of Tel Aviv University said that the current study provides experimental evidence for the prey-luring function of fluorescence in corals

The oceans are home to a variety of wonderful marine life that has given rise to diverse ecosystems. Corals, which come in a wide variety of forms, dimensions, and hues, are no exception. Even some animals light at night. A group of Israeli scientists has now determined why that might be the case. Deep-reef corals may emit dazzling colours from their luminous green and yellow tentacles to entice creatures to feed on them.

Coral reef researcher Or Ben-Zvi of Tel Aviv University said that the current study provides experimental evidence for the prey-luring function of fluorescence in corals despite the limitations in the current understanding of the visual interpretation of fluorescence signals by plankton.

Most reef-building corals take advantage of the sunlight that filters down from the ocean surface by basking in the shallow waters where their resident algae can absorb it. These are the coral reefs that we are familiar with and adore, complete with photosynthetic zooxanthellae. Other hardy coral species, however, are able to develop up to 6,000 metres (20,000 feet) beneath the surface in the cold, dark depths of the ocean.
The authors of this new study hypothesised that, like other deep-sea inhabitants that create bioluminescence, these fluorescent deep-water corals would employ light to entice their food, like tiny plankton, into their fold. But they had to put that notion, which they called the "light-trap," to the test.
Marine ecologist and senior author Yossi Loya of Tel Aviv University explained that the mouths or tentacle tips of many corals are highlighted by a bright colour pattern. For corals that are rooted to the bottom, being able to glow and attract prey seems like a pretty crucial adaptation, particularly in settings where corals require alternate energy sources in addition [to] or as a substitute for photosynthesis.
However, a number of additional theories have been put out to explain why coral fluoresces. For instance, the "sunscreen" idea postulates that fluorescence may shield corals that have bleached from additional heat stress and light deterioration. Another explanation would be to increase photosynthesis.
There is currently no proof that the fluorescence of mesophotic corals, which thrive in low, blue-shifted light, provides any form of defence or energy boost.
The scientists evaluated whether teeny shrimp (Artemia salina) preferred a green or orange fluorescent target over transparent, reflecting or matt-colored targets placed on the other side of a tank in a series of laboratory studies. In fact, the shrimp were drawn to the fluorescent signal and swam that way.
Meanwhile, it's significant to highlight that only one species of mesophotic coral was examined in this study. The perception of colour by plankton and other crustaceans that support coral reefs also need further study because it probably varies depending on the species, the environment, and the stage of life.
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