From bright gold, to sapphire and deep blue, these tiny copepods are the luminous gems of the sea that make the water sparkle as if it was filled with diamonds. Like diamonds, Sapphirina copepods are clear and they don’t make their own light. Instead, they reflect it. One minute they’re completely invisible, and the next, they’re flashing brilliantly.
So, unlike bioluminescent sea creatures whose colorful displays are the result of chemistry, these copepods rely on structure for their flashiness. The cells of their translucent skin contain layers of hexagonal plates which reflect light in various colors depending on their size and arrangement. According to biologist Rebecca Helm from Brown University, when you see these guys shimmer, you’re seeing a process similar to the one that causes the sheen of an oil slick. You can see just what she’s talking about in the awesome video she’s included in her reverent ode to the sea sapphire.
Coincident, or proof that everything is connected? It’s only males of the species that produce the flashy colors. The females live inside the translucent bodies of salps and have huge eyes compared to the males. Perhaps they peer out from their homes in search of the flashiest mate.