why does shrimp turn orange when you cook them?

Shrimp, crab, and lobster contain astaxanthin in their shells. This is very similar to the beta-carotene that makes carrots orange.

The other colors are unstable; astaxanthin is not. Thus, once you cook the shrimpies, the green color disappears, leaving nothing but the orange.

(My wife says it is *nothing* like that, and rather the shrimp are just blushing from embarassment. She's a blonde, and a bombshell, and knowing what's good for me, I am forced to admit that the first couple of paragraphs here are a misconception on my part, with my wife's version being true.)

Not only shrimp but lobster and crab also.

The lobster, shrimp, and crab shells have two colors: blackish and orange-pink. Crustaceans look blackish while alive because the orange-pink color exists but is hidden.

According to chemistry: to get down to the basics of molecular structure to elucidate. The blackish color is due to protein chains. The orange-pink color is a pigment, similar to the one in carrots. The protein chains hide the orange-pink molecules by wrapping around and containing them. Therefore the shell looks blackish.

What happens if you steam the shrimp or lobster? The protein chains undergo a chemical change when heated: they uncoil and release the orange-pink molecules. The orange color is no longer hidden, and the shell turns orangish-pink.

all natural foods have sugars. and the sugars in the shrimp are being cooked. in other terms its called caramelization.

i think its because the meat is cooked. not fleshy watery but become solid and compact. i think it goes the same for human if they were to get cooked.