A whale louse is a commensal crustacean of the family Cyamidae. Despite the name, they are not true lice (which are insects), but rather are related to the better-known skeleton shrimp, most species of which are found in shallower waters. Whale lice are external parasites, found in skin lesions, genital folds, nostrils and eyes of marine mammals of the order Cetacea. These include not only whales but also dolphins and porpoises.