The deep sea is more colorful than we thought. Corals living 165 feet beneath the surface of the Red Sea glow green, yellow, and red, according to a new report by an international team of scientists in PLOS ONE.

Green fluorescent corals have been routinely observed in shallow waters, but the deep water corals spotted off the coast of Eliat, Israel are unusual for their wide spectrum of color. Orange-red colors are absent from shallow reefs, but present at greater depths of 165 to 195 feet below the surface.

Fluorescent pigments act as a kind of sunblock for coral at shallow depths, protecting it from harmful UV rays. But some of the corals produce a fluorescent glow even in the absence of a light source in regions of the ocean where getting any sunlight at all can be difficult. These corals don’t need sunscreen. So why the glow?

While scientists are still figuring that out, it might be a way to get more light to the symbiotic algae that live in the reefs and produce oxygen for the corals. These zooxanthellae undergo photosynthesis, so the light produced by the corals may help them survive and thrive at greater depths in the absence of sunlight.

The pigments found in corals might also be useful in scientific laboratories. The fluorescent pigments could be used to highlight specific cells or structures in biomedical imaging.

[h/t: Nature News]

All images by Prof. Jörg Wiedenmann