Shrimp is the most popular seafood in the United States. These slightly sweet, mild-flavored crustaceans are full of interesting science. Take a deep dive into these fascinating facts. They Change Color When They Cook Most raw shrimp are a gray-black color. But when you cook them, they turn pink. Why the color change? Shrimp contain a pigment called astaxanthin that is released when the shrimp reach about 120 degrees. Bonus fishy fact: Salmon have pink flesh because they eat shrimp and krill, a shrimp relative that contains the same pigment. They Come In Lots of Sizes There are about 2,000 species of shrimp around the world, and humans eat around 300 of them—from common whiteleg shrimp to beautiful royal red shrimp. Some species are harvested when they’re super tiny, dried, and used in all sorts of dishes, including soups, salads, and stir-fries. On the other hand, black tiger shrimp can …