Nurse sharks are carnivorous and consume a variety of sea-dwelling creatures. Although they have been known to bite humans when provoked, they are not man-eaters. They consume a variety of fish, marine invertebrates and crustaceans small enough to fit in their mouths.
Nurse sharks eat everything from shell fish to octopi, and their success as a species is partly due to their widely varied diet. These slow-moving, bottom-dwelling sharks suction-feed in crevices during the night or patrol flats and sand banks looking for crabs, crustaceans and octopi. They find their prey by swimming close to the bottom, grazing it with two oral barbels. When they sense prey, they strike quickly, plunging onto the bottom and sucking in their prey along with sand, silt and other debris. They filter out the unwanted particles through their powerful gills while consuming their prey.
Although nurse sharks have comparatively small teeth, they are razor-sharp, and the jaws are incredibly powerful allowing them to easily crush the protective shells of crustaceans including crabs and conch. The nurse shark, like other sharks, loses teeth frequently, but these are replaced by a new row that moves forward from the back of the mouth while the front-most row sloughs away, keeping its teeth sharp and ready to crush shells.