Morays feed largely on other fish caught as they work their way through coral reefs. Some morays are equipped with teeth in the back of the mouth for crushing hard-shelled animals such as clams and oysters. Morays are occasionally caught on hook and Morays are occasionally caught on hook and line by fishermen, sometimes are captured by trawlers that drag nets over the bottom. People in some parts of the world value the moray as food. Some Pacific morays measure as long as 10 feet and are considered dangerous to man when aggressions are aroused, generally by divers' actions.
Several records exist of attacks on humans by wounded morays.
It is the silvery substance in the skin of herring and other fishes. Pearl essence is a lucrative byproduct of herring fisheries inasmuch as it is essential to the manufacture of lipstick, nail polish, paints, ceramics, and costume jewelry. In life the blue shark displays a brilliant blue color on the upper portion of its body and is normally snowy white beneath. The blue quickly fades to dull grey after the shark is killed. The mako and porbeagle sharks also exhibit a blue coloration, but it is not nearly as brilliant as that of a blue shark.