Why Lobsters Turn Red After Getting Cooked

As a kid, it always comes as a surprise when you finally see a real breathing lobster (either in Seaworld or television) and see that it’s not color red. Wait, what? The ones your mom always serves at the dinner table are red, so what gives this color? Why are they bluish-green?

Of course, the bluish-green color makes a whole lot of sense. These creatures live on the seafloor after all. And that specialized blue pigment that gives them their color helps them blend into the seafloor. They then use this for protection from predators and as a camouflage for prey. It’s just Mother Nature working its magic.

However, come the dinner table, and these lobsters are suddenly all bright red and eye-popping. So, when does the color shift happen? And why?

Turns out, our tiny little kid minds aren’t the only ones confused. Scientists too, from way back in the 1870s. Unfortunately for them, a century would pass before biochemistry happens, which is a branch of science that’s able to finally answer the lobster question.

Essentially, two molecules make up lobster camouflage. The first is crustacyanin, which is a protein. The other one is a carotenoid, which is called astaxanthin. However, lobsters have no capability of producing their own astaxanthin. They simply get it from what they eat.

"It's very similar to beta-carotene . " Flamingos eat shrimp  with beta-carotene and turn pink. When a lobster eats astaxanthin, it gets absorbed into their body,” said Anita Kim, an assistant scientist at the New England Aquarium in Boston. 

And while astaxanthin on its own is red, it turns into blue when bound by crustacyanin. Per a research made back in 2002, the crustacyanin present in lobster’s bodies twist astaxanthin, therefore changing how it would reflect light.

However, when lobsters get heated (as they are being cooked), the crustacyanin reorganizes and and loses their shape, “releasing” the astaxanthin and therefore revealing its true color, which is red.

However, while scientists have already nailed down the chemistry behind it, they’re still unsure crustacyanin can temporarily make the pigment blue. "Why astaxanthin is blue when it's bound is being investigated," per the scientists.

lobster According to biologist Simon Watts, there doesn’t seem to be a built-in life expectancy in the lobster's cells. Jo Jakeman, CC BY 2