夜晚会发出蓝光的海滩

有些海滩会在黑暗中发光。不是因为灯光，也不是因为月光。每当海浪拍打沙滩，海水本身就会发出蓝色的光。沿着海边走，你身后的脚印也会闪出蓝光。标记那个你愿意在半夜把他拖下床、一起来看这个景象的朋友。

Some beaches glow in the dark. Not from lamps, not from the moon. The water itself lights up, electric blue, every time a wave breaks on the sand. Walk along the edge and your own footprints flash blue behind you. Tag the friend you would drag out of bed at midnight to see this.

这种光来自数十亿个微小的海洋生物，它们实在太小，无法一个个看清。当周围的海水晃动时，它们的身体会发出短暂的蓝光，有点像海里的萤火虫。科学家把这种现象叫做“生物荧光”。一道破碎的海浪会同时晃动数百万个这样的生物，整片浪花因此短暂地燃起蓝色的光。

The light comes from billions of tiny sea creatures, far too small to see one by one. When the water around them moves, their bodies make a quick flash of blue light, a bit like a firefly of the sea. Scientists call this living light. A breaking wave shakes millions of them at once, and the whole wave burns blue for a moment.

它们为什么要这样做？这闪光其实是一种警报。当一个小猎手游过它们身边，海水开始发光，体型更大的猎手就能立刻看到晚餐在哪里。于是这些小生物用发光来召唤危险的帮手。对它们来说，这是求生的办法。而对半夜站在海边的人来说，眼前的大海就像洒满了坠落的星星。

Why do they do it? The flash is a kind of alarm. When a small hunter swims through them and the water starts to glow, bigger hunters can suddenly see where dinner is. So the little creatures light up the sea to call for dangerous help. For them it is survival. For anyone standing on the beach at midnight, it looks like the ocean is full of fallen stars.