The nurse shark, Ginglymostoma cirratum, is a shark in the nurse sharks (Ginglymostomatidae) family, the only member of its genus Ginglymostoma. Nurse sharks can reach a length of 4.3 m (14 ft) and a weight of 330 kg (730 lb). The nurse shark family name, Ginglymostomatidae, derives from the Greek: from meaning hinge and meaning mouth. Cirratum also derives from Greek, meaning curl or swim. Based on morphological similarities, Ginglymostoma is believed to be the sister genus of Nebrius, with both being placed in a clade that also contains the short-tail nurse shark (Pseudoginglymostoma brevicaudatum), the whale shark (Rhincodon typus), and the zebra shark (Stegostoma fasciatum). The nurse shark is a common inshore bottom-dwelling shark, found in tropical and subtropical waters on the continental and insular shelves. It is frequently found at depths of one meter or less but may occur down to 75 m (246 ft).