Nocturnal and generally slow and sluggish, nurse sharks spend much of their time resting on the ocean's bottom. They tend to rest in groups during the day, with up to 40 individuals piled on top of one another, and hunt alone at night. Unlike many sharks, this species is thought to be non-migratory—the nurse shark adapts to cold by becoming even less active!
The nurse shark is light yellowish-brown to dark brown, and some have small dark spots. It has a flattened body and a broad, rounded head with two conspicuous barbels between the nostrils, which it uses to find food. A nurse shark’s mouth is filled with rows of small, serrated teeth for crushing hard-shelled prey. Although they’re docile and mostly harmless to humans, they’ve been known to bite in self-defense.
Aquarium guests sometimes think this shark is in trouble when they see it lying on the bottom of the Shark Alley exhibit. In fact, this behavior is completely normal for this species, which is more active at night and (unlike some other species of shark) can breathe while lying still. Look for movement of the nurse shark’s gill slits as it pumps water over its gills to obtain oxygen.
Learn more about nurse sharks! Did you know this shark can use its large front fins to “walk” along the ocean floor?
Common in tropical and subtropical coastal waters of the Atlantic and Eastern Pacific, nurse sharks often inhabit reefs and rest during the day on sandy bottoms or in caves and crevices. They show a strong preference for certain resting sites, repeatedly returning to the same spot after hunting for food.
Although they are generally sluggish, nurse sharks slurp up benthic, or bottom-dwelling, organisms with amazing speed. They feed on spiny lobsters and other crustaceans, small stingrays, sea urchins, squid and bony fishes.
Female nurse sharks, averaging 7.5 to 9 feet in length and 165 to 230 pounds, are slightly larger than males.
Nurse sharks do not have special conservation status. Males reach sexual maturity at 18 years; females at 20 to 22. Females produce a litter of about 20 to 25 pups every other year.
No species is known to regularly prey on nurse sharks, although scientists have found evidence that they are sometimes food for other sharks, including lemon, tiger, bull and great hammerhead sharks.
As curator of Blue Wonders: Reefs to Rainforests, Jay Bradley oversees the care of all animals in Blacktip Reef, Living Seashore, Shark Alley and more.
The National Aquarium—and the aquatic world—is full of amazing animals like this one.