Over billions of years, corals have worked out a special arrangement with algae: Corals give them shelter and algae convert light into food for the corals. Corals do other things for the algae, too. In deeper water, it's dark and the little light that reaches that far down is only in the blue part of the spectrum. Somehow, there are corals that live up to hundreds of feet below the surface and also manage to glow burning hues of orange and red. The reasons for this fluorescence have remained a mystery, until now: These deep-sea corals glow to get more sunlight, according to a study published in the journal Proceedings of the Royal Society B. Their proteins soak up the scarce light and shine it back out as red-orange light that penetrates deep inside their tissues where their microscopic roommates take up residence. This means there's light for photosynthesis, and the algae creates energy and food for the coral.

How mercury makes its way to the Arctic

The remote Arctic tundra may seem like the last place on Earth human pollution should be causing a problem — yet it's filled with mercury contamination. And that mercury leaks from the soil into rivers and ultimately the Arctic Ocean, contaminating the fish and other sea life that native communities rely on for survival. In a new study in the journal Nature, scientists have begun to outline how the mercury is getting into and moving through the landscape. And the short answer is: It's our fault it's there in the first place, and climate change could now make that even worse. The study finds that the majority of the contamination in the Arctic tundra came from a gaseous form of elemental mercury, carried through the atmosphere from other parts of the world, where it was emitted to the atmosphere as a result of the burning of coal and other industrial activities. Once it reaches the Arctic, the scientists believe the mercury is sucked up by plants — mainly in the summer, when snow cover is at its lowest and the tundra is at its greenest — in much the same way that vegetation pulls carbon dioxide out of the air. As the plants shed their leaves or die, the mercury moves into the soil and eventually may leach into rivers and waterways, which carry it into the Arctic Ocean.

News services