You probably know that flamingos are pink because of the shrimp they eat. (Well, technically because the algae they and their shrimp meals eat has beta carotene in it — like carrots do, and it's turned their feathers pink.)
But where did pink dolphins' color come from?
Before we get to that, first we need to establish that there is more than one kind of pink dolphin.
This is probably the pink dolphin you're most familiar with. Also known as the boto dolphin, these freshwater-dwelling cetaceans can be all pink, semi-pink or not pink at all.
University of Florida researcher Vanessa Mintzer told BBC Earth, "Typically, younger animals are gray and they get pinker as they age. Usually the adult males are the pinkest."
There are a few theories as to why these dolphins appear this way.
BBC Earth notes that perhaps the boto dolphins' scar tissue is pink, and the more scrapes and teeth rakes they get, the pinker they get.
After all, scar tissue is how Risso's dolphins turn from gray to white.
Another theory is that the pink hue is a defense mechanism — a way to hide in the red mud of the river. As for those with gray backs and pink bellies, it could be a countershading to appear invisible from animals looking up or predators looking down.
Great white sharks have the same countershading.
But, just like we don't know for sure how many of these boto dolphins there even are, we don't know for sure if these hypotheses are correct. They're a mysterious species.
These endangered Hong Kong inhabiters may be called white dolphins, but many of them appear pink.
That's because their blood vessels are showing through their white skin.
According to Marine Mammal Science, their red blood vessels are "overdeveloped" to regulate their body temperature in the waters off China. NatGeo elaborates that this "network of blood vessels" is constructed close to the surface of their white skin, and makes them appear pinker.
In the waters off Louisiana, a bright pink bottlenose dolphin can sometimes be spotted.
Nicknamed Pinky, she's captured public attention for her stark rosy hue.
Bottlenose dolphins are usually gray, but NatGeo reports that Pinky is actually an albino dolphin. Even if her parents were both gray, if they both carried the gene for albinism, Pinky won the gene pool lottery and was born without color.
And, because of this lack of skin pigment, her blood vessels are showing through her light skin and making her appear pink — much like the Chinese white dolphins.
There's even a rumor that Pinky had her own pink baby, according to the Miami Herald — although sightings of her calf are unconfirmed at this time.