Tropical to warm temperate latitudes in the eastern Pacific and eastern and western Atlantic oceans
Coral and rocky reefs and associated sand flats
Order Orectolobiformes (carpet sharks), Family Ginglymostomatidae (nurse sharks)
The nurse shark is one of the most commonly observed sharks on coral and rocky reefs of the eastern Pacific Ocean and the eastern and western Atlantic Ocean. Given that nurse sharks give live birth and that individuals (even juveniles) have relatively small home ranges, it is surprising that all individuals across this large, tropical to warm temperate distribution are the same species. An extensive genetic study of the nurse shark may reveal the existence of different species in different ocean basins (e.g., on either side of Central America).
Nurse sharks are very easy to identify. They reach fairly large sizes (10 feet/3 m), but unlike most large shark species, they are not grayish in coloration. Instead, they are yellowish-brown. They also have characteristically round heads, barbels that they use to search for prey, and very small eyes. Nurse sharks are one of the species of sharks that are able to remain perfectly still, and they spend most of the daylight hours resting in caves or under ledges, sometimes in groups of several individuals. During the twilight hours and at night, they become much more active and feed on fishes, rays, and invertebrates. They are suction feeders and can generate enough pressure to suck a Queen Conch right out of its shell. Like many suction feeders, nurse sharks swallow their prey whole.
Because they are inactive during the day, remain perfectly still, and are not targeted by fisheries throughout their range, nurse sharks are the most common species of shark that SCUBA divers or snorkelers experience on reefs within their range. Historically, other sharks were probably more common, but heavy fishing pressure has changed the community in many areas. Though they seem harmless while they sleep during the day, it is unwise to pet nurse sharks or to pull on their tails. Some individuals have been known to bite divers or swimmers who startled them awake, certainly as a means of self-defense. Global nurse shark population trends are unknown, but they have been depleted in some places as a result of overfishing.