Nurse Shark: Where and when to dive with them

When diving with nurse sharks, it's crucial to remember that while generally docile, they are still wild animals. Maintain a respectful distance, typically several feet, and never attempt to touch, ride, or provoke them. Harassment can lead to a defensive bite, particularly if their escape route is blocked. They are often found resting motionless under ledges or in coral formations during the day, making them easy to observe without causing disturbance. Look for their distinctive barbels near their mouths and their small, sandpaper-like dermal denticles when identifying them. To spot them, pay close attention to sandy patches adjacent to reefs, under large coral heads, and in the entrance of small caves. Their cryptic coloration helps them blend into the seabed. If a nurse shark is encountered free swimming at night, observe its natural foraging behavior from a distance. Avoid sudden movements or loud noises that could startle them. Respect all local dive regulations and marine park rules regarding wildlife interaction; in many areas, feeding marine life is strictly prohibited and can alter their natural behaviors. Remember, we are guests in their underwater home, and observing them undisturbed in their natural habitat is the most rewarding and ethical approach.

Nurse sharks can be encountered year-round in their tropical and subtropical habitats, but certain seasons offer peak visibility and activity. In the Florida Keys and the Bahamas, nurse sharks are reliably present throughout the year, with summer and early fall (June to October) often providing the warmest water and best diving conditions, which encourages more activity. Similarly, in the Mexican Caribbean, including Cozumel and the Riviera Maya, they are a consistent presence. The dry season (November to April) often brings calmer seas and excellent visibility, although the sharks are equally present during the wetter, warmer months. Their nocturnal feeding habits mean they are often found resting during daylight hours, making specific seasonality less critical for sightings than for open-water pelagics. Divers visiting regions like the Galapagos Islands or Cocos Island in the Eastern Pacific can also expect to see them, with June to December often considered the height of shark season due to abundant food sources, though nurse sharks are resident and present year-round. Generally, any time is a good time to spot a nurse shark in their preferred warm water environments.

Nurse sharks are benthic, slow-moving sharks found in tropical and subtropical waters of the Atlantic and Eastern Pacific Oceans. In the Atlantic, their range extends from Rhode Island down to Southern Brazil, including the Caribbean Sea and the Gulf of Mexico. Notable dive destinations include the Florida Keys, the Bahamas, and throughout the Yucatan Peninsula in Mexico, particularly around Cozumel and the Riviera Maya. In the Eastern Pacific, they inhabit coastal waters from Baja California to Peru. These sharks prefer shallow waters, typically less than 20 meters deep, but can be found down to 70 meters. They are commonly associated with coral reefs, rocky crevices, mangrove fringes, and seagrass beds, where they seek shelter during the day. During nighttime, they become more active, venturing into open sandy areas to forage. Divers often encounter them resting in underwater caves or under ledges, sometimes in groups, particularly juvenile sharks. Their sedentary nature makes them a frequent and welcome sight on many reef dives.

Nurse sharks are opportunistic, nocturnal predators with a specialized diet favoring bottom-dwelling invertebrates and small fish. They are not fast pursuers but instead excel at suction feeding. Their small mouths and powerful buccal pump allow them to create a strong vacuum, literally sucking prey out of crevices, under rocks, or from sandy substrates. A significant portion of their diet consists of crustaceans, such as crabs and lobsters, and mollusks, including octopuses and conchs. They also prey on a variety of small reef fish, particularly those that are slow-moving or found resting at night. Unlike many other sharks, nurse sharks do not typically engage in active, high-speed chases. Instead, they methodically patrol the seafloor, using their keen sense of smell and barbels to locate hidden prey, often probing into coral heads and sandy patches. Their feeding strategy is adapted for extracting hidden or sedentary organisms, making them a formidable scavenger and predator of the reef’s bottom-dwelling community.