Ginglymostoma cirratum
A large-headed shark with nasal barbels and dorsal fins about the same size. 
Gray-brown, yellow brown or brown body. Juveniles may have dark spots.
Most individuals encountered by divers are less than 10 ft [3 m] total length. Males take about 10 to 15 years to mature, and reach maturity when they are about 8.2 ft [2.5 m] in length and will grow to at least 8.4 ft [2.57 m]. Females take 15 to 20 years to mature, and reach maturity when they are about 7.5 to 7.8 ft [2.3 to 2.4 m] and will grow over 8.5 ft [2.59 m] in length. Maximum length is said to be 14 ft [4.3 m] but most are less than 9.8 ft [3 m].
Teeth are similar in both jaws: a single large cusp, flanked on each side by 2 smaller cusps.
Inshore from intertidal to depths of 165 ft [ 50 m] on rock and coral reefs, in channels in mangrove keys and reef flats.
Western Atlantic from southern Brazil to Cape Hatteras with strays to Rhode Island, including Gulf of Mexico and the Caribbean Sea. Eastern Atlantic in Cape Verde Islands and along the coast of west Africa. Eastern Pacific from southern Baja to Peru.
Prey – small fish and invertebrates: lobster, shrimps, crabs, squid, sea urchins, octopus, snails and bivalves.
Reproduction – Ovoviviparous. Litters range from 21 to 30. Size at birth is 8.25 to 11.8 inches [27 to 30 cm].
The shark is nocturnal; it is an active strong swimmer at night, but is sluggish by day. The shark uses its muscular pectoral fins to clamber over the bottom, but divers usually see the shark lying motionless on the bottom, often with its head in a crevice. By day, nurse sharks may rest in aggregates of 2 to more than 30 individuals, leaning against or atop one another. The shark has a well-defined fixed home range and it may return to the same daytime resting site for long periods of time.
Placid and usually indifferent to divers.
Danger to humans – Nurse sharks have retaliated when provoked by divers or swimmers.