A closeup of the skin of a nurse shark, Ginglymostoma cirratum, on the Sugar Wreck north of Grand Bahama Island in the northern Bahamas. The nurse shark is a large, sluggish, bottom-dwelling shark that is generally harmless unless provoked. It has very strong jaws, a stout body, and a wide head with obvious barbels (thin, fleshy, whisker-like organs on the lower jaw in front of the nostrils that sense touch and taste). The skin is dark gray-brown on top and some nurse sharks, especially the young, have spots. The nurse shark is smooth to the touch, unlike most sharks. They are nocturnal hunters that rest during the day in groups. Nurse sharks do well in captivity.