the light that answers a touch
Vieques, an island off Puerto Rico, has a bay where the water answers a hand. Drag a paddle through and the trail glows blue-green, brighter than the sky. Hundreds of thousands of glowing cells per gallon, over a million by some counts. The light is not reflection. Each spark is Pyrodinium bahamense, a cell whose flash is a chemical reaction set off by movement. Best guess: a burglar alarm. The flash says something is here, and something bigger comes for whatever was about to eat the cell. The US Navy held this land until 2003 and kept everyone off it. That darkness is part of why the light survived. In 2017 Hurricane Maria shoved the water out and wrecked the mangroves. For a time, the bay went dark. It came back slowly. Kayak tours run again, and the guides ask you not to swim or wear repellent, which kills the cells you came to see. The oldest evidence of bioluminescence is 540 million years old. The oldest eyes in the fossil record are ten million years younger. For that stretch of deep time, light answered touch and nothing we know of could see it. It glowed with no audience. It glowed anyway. On a moonless night, put your hand in the water. Something will answer.