95% of the adult horn shark's diet consists of hard-shelled mollusks (e.g. bivalves and gastropods), echinoderms (e.g. sea urchins) and crustaceans (e.g. crabs, shrimp, and isopods). To crack their shells, the horn shark generates the highest known bite force relative to its size of any shark, well in excess of other measured species such as the spiny dogfish ("Squalus acanthias") and the blacktip shark ("Carcharhinus limbatus"). One study found the average bite force for this species in the wild to be 95 N with a maximum of 135 N, while under experimental conditions sharks could be induced to bite with over 200 N of force. Large horn sharks that feed mainly on sea urchins (particularly the short-spined purple urchin, "Strongylocentrotus purpuratus") have their teeth and fin spines stained purple.