Nurse sharks are common in the tropical waters of the Western Atlantic. They are frequently found in aquariums and easily kept in captivity. They prefer water temperatures between 20° - 30° C (68-86° F). Nurse sharks hardly move at all during the daytime, and researchers believe that they inhabit one location for much of their lives. They can frequently be found sitting motionless, often piled on top of one another, while resting on the ocean floor. They may also be found in caves or under coral reefs. They are nocturnal hunters, foraging at night, and tagged individuals have been identified returning repeatedly to the same caves or resting sites at the end of each night's hunting.
Since Nurse sharks prefer warm temperatures and feed on non-migratory animals such as spiny lobsters, small squid, and mollusks, these sharks stay in the same tropical locations all their lives. One of the mysteries of migration is that Nurse sharks are occasionally found in New England in the summer, but not in the winter when the water temperature drops well below 20° C (68° F). Why are Nurse sharks found at all in a region where water temperatures clearly drop below their range? Do some Nurse sharks migrate? If so, where do they go? Do they hibernate like bears by slowing down their metabolism (Nurse sharks clearly eat less when the water temperature is cold, feeding only once every two weeks or so) ? No one knows for certain where they are in the cold months of the year in New England.