In a few rare places in the world, there are salt lakes that are flamingo pink.

To understand what gives them their bright color, we should first understand what makes flamingos pink.

The birds spend much of their lives wading and feeding in shallow lakes that aren’t pink but are salty and hold the flamingo’s favorite food: brine shrimp.

These shrimp are pink, colored by high concentrations of beta-carotene—the same pigment that makes carrots orange. After a couple years of eating shrimp, flamingos, which start out gray, have consumed enough beta-carotene to turn their feathers pink.

But what makes the shrimp pink? It’s also something they eat.

In these salty lakes lives a particular kind of microalgae adapted to the saline water.

It starts out green, but to protect itself from UV radiation, produces a pigment that acts as a natural sunblock: beta-carotene. Which turns the algae … pink.

So, pink algae make pink shrimp, which make flamingos pink.

But what about the pink lakes? They don’t have any flamingos in them. In fact, they’re so salty that almost nothing can live in them, except that microalgae.

And there’s so much of it that it colors the water red. When the sun shines through it and bounces off the light-colored bottom, we get a bright, flamingo-pink lake.

These pink lakes are valuable sources of both salt and beta-carotene, and for many years people have visited them to collect both.