Methods for the identification of individual crustaceans are needed in many types of studies. Snow crab (Chionoecetes opilio) individuals have distinctive natural patterns of tubercles and spines on the carapace. The results of a double-marking experiment using these natural markers along with genetic (microsatellite) markers confirm that natural markings are a reliable means of recognizing individuals within groups of tens to hundreds of snow crabs. These natural markings are persistent through at least two molts. They have already demonstrated their usefulness in laboratory studies of molting and mating and could be applied to a wider spectrum of investigations. A cursory examination suggests that similar carapace features could be used to identify individuals in other crustacean species as well.