Crustaceans

Crustaceans are a very large group, consisting of over 50,000 species, including some of the most familiar — and popular — shellfish, such as prawns, crabs, rock lobsters and bugs. All of these edible crustaceans belong to the order ‘decapod’ (meaning ten-footed). They all have a shell that they shed and replace as they grow. Despite being various colours in their raw state, all crustaceans turn red when cooked because their shells contain a carotenoid pigment called astaxanthin (the best known carotenoid pigment is carotene, which gives carrots their bright orange colour). Astaxanthin’s colour isn’t obvious in live or raw shellfish because it’s bound with a protein that usually creates a blue-green colour: astaxanthin is heat-stable and the protein isn’t, so when heat is applied the protein is destroyed, releasing the pigment and giving the typical red colour of cooked shellfish.