Nurse Shark

The nurse shark is a large, docile bottom-dwelling shark in the family Ginglymostomatidae. It is one of the most commonly encountered sharks in shallow tropical and subtropical Atlantic waters, frequently seen resting motionless in caves, under ledges, or on sandy bottoms during the day. Nurse sharks are easily recognized by their broad, flattened heads, small eyes, and a pair of long barbels near the nostrils that help them locate prey buried in sediment. Despite their large size, they are generally slow and non-aggressive, relying on suction feeding to capture small fish and invertebrates hidden in the substrate. The species is currently assessed as Vulnerable in parts of its range due to habitat loss and fishing pressure, though it remains locally abundant on many reef systems.

Distinguishing features of the nurse shark:

• Broad, flattened head with a blunt snout and small, widely spaced eyes
• Two long barbels hanging from the front of the nostrils
• Yellow-brown to grey-brown skin, usually plain but sometimes faintly spotted in juveniles
• Two rounded dorsal fins of similar size, positioned well back on the body
• Rounded pectoral fins and a long, low upper tail lobe

Adults typically measure 2.1-3 m. Nurse sharks are distinguished from similar bottom sharks (such as wobbegongs) by their smooth, unadorned skin and simple barbels rather than fringed skin flaps.

Nurse sharks favor warm, shallow coastal waters of the western Atlantic, Caribbean, and eastern Pacific, typically in depths of less than 30 m, though they occasionally range deeper. They prefer coral reefs, rocky ledges, seagrass beds, and mangrove-lined shorelines, where they rest in caves, crevices, or under overhangs during daylight hours. Juveniles often use shallow, sheltered nursery habitats such as tidal flats and mangrove creeks. Nurse sharks are highly site-faithful, frequently returning to the same resting sites over multiple years, and tolerate relatively warm water temperatures, generally staying in waters above about 20°C.

Nurse sharks are nocturnal, becoming active at night to forage for small fish, crustaceans, and mollusks along the seafloor, which they capture using powerful suction created by their small mouths. During the day they are largely inactive, often resting in groups, sometimes stacked on top of one another, within caves or under ledges. They are ovoviviparous, with females giving birth to litters of around 20-30 pups after a gestation period of roughly five to six months, typically on a biennial cycle. Nurse sharks are generally docile and slow-moving, relying on camouflage and stillness rather than speed to avoid predators, and play a role in controlling benthic invertebrate populations on reef systems.