The nurse shark can also detect prey hidden in rocky crevices. Sensing a meal, it cups its lips over the crevice opening and, by expanding its throat, creates a strong vacuum and sucks out the prey. Adult nurse sharks average seven to 10 feet in length, but can reach a length of 14 feet. Average weight is between 350 and 400 pounds. The sharks gather in groups in shallow water to mate, and produce up to 30 live pups, measuring 12 inches long.
Nurse sharks vary in color from tawny to dark brown.
Older sharks have deep golden brown skin with diamond-shaped dark and light flecks. People in some countries once fished nurse sharks commercially for their oil, and their skins were highly prized for leather. Their fins were also said to be good eating. Like all wild animals, nurse sharks will bite if provoked. Divers who try to seize a nurse shark by the tail risk a painful bite.