Nurse shark (Ginglymostoma cirratum) is a bottom-dwelling predator that resides beneath the warm, sunlit waters of tropical and subtropical oceans. Often characterized as docile and sluggish, these sharks possess remarkable adaptations and play a vital role in maintaining the balance of marine ecosystems.
Although how they got the name “Nurse shark” is unknown, they are called “couch potatoes” due to their lazy, peaceful behavior and their habit of sucking and eating up tiny living creatures on the ocean floor as they swim past.
Although they are of the shark species, but they are different from their aggressive, scary-looking counterparts. But just what makes them so unique? Let’s find out.
Appearance
Nurse sharks can be easily identified from the rest of the shark species due to their different appearance. They have wide bodies with round heads, small rectangular mouth and their dorsal fins are rounded rather than sharp. Their skin is smoother than most sharks and their color leans towards yellowish-brown rather than grey.
They can grow up to 9 feet long and have two sensory organs called ‘barbels’ that grow under their mouth. These barbels are their “taste buds” and they drag it across the ocean floor to find small fishes and crabs hiding in the sand.
They are generally harmless to humans and are slow-moving ocean-floor dwellers. They are nocturnal predators, but they are very social. During the day, they rest on sand or between reef crevices with piles of around 40 other Nurse Sharks or similar-sized sharks.
Did you know…
Nurse Sharks can breathe even when staying still, unlike the other sharks that need to constantly swim to breathe. This phenomenon is known as Buccal Pumping. They use oral muscles to actively suck water into their mouth and this supplies oxygen into their gills.
Habitat
The Nurse Sharks are usually found in the tropical and subtropical warm waters in the Western Atlantic and Eastern Pacific oceans. They live in depths ranging from 3 to 250 ft. In the Atlantic Ocean, they are found from Rhode Island to southern Brazil, the Caribbean, and the Gulf of Mexico.
These nocturnal animals rest on sandy bottoms or in shallow-water caves and rock crevices during the day and are active during the night, often swimming near the bottom or clambering across the sea floor, using their muscular pectoral fins as limbs.
In the eastern Atlantic, they can be spotted from the Cape Verde Islands to the African coast. These sharks are usually spotted roaming around the coral reefs or resting on salt flats and between mangrove islands. They also exist next to human activity.
Diet
Although peaceful, these sharks are carnivorous but without being violent. They usually feed on, mollusks (octopi, squids, shrimp), sea urchins, crustaceans and stingrays. Their mouths allow them to suck and feed at an incredible speed.
Their strong jaws are filled with rows of small, serrated teeth for crushing hard-shelled prey.
Their nightly hunts are also a major factor in their fast-eating habits as most of their prey are asleep and unguarded at overnight hours. They are also known to bite and chew on corals as well.
Reproduction
Males reach sexual maturity at 18 years; females at 20 to 22. Female Nurse Sharks often mate with more than one male, with the mating season starting in May and lasting till July. Numerous males will attempt to mate with a single female simultaneously by biting her pectoral fin and shoving her to one side.
The female sharks have a six-month gestation period and then give birth to around 40 juveniles. The baby sharks, from a single birth, could have up to six different fathers. Once the birthing is over, the mother won’t mate for another 18 months. She stays in shallow waters with her pectoral fins buried in the sand to avoid the males.
Threats
Although the conservation status of the Nurse Sharks is unknown since the data on their numbers are insufficient, they are said to be under threat from humans since they are a target for commercial fishing.
Their flesh is considered to be delicious, and their skin is used for leather. Since they are slow, docile, and live near humans, they are easy to hunt. They are protected in some areas due to ecotourism, but like the overall state of the ocean floor, the numbers of these sharks are starting to waver.
6 More Fun Facts about Nurse Sharks
- They become more active at night, using their sensitive barbels and electroreceptors to locate prey in low-light conditions.
- Nurse sharks have powerful suction capabilities, allowing them to vacuum up their food.
- Nurse sharks are often found in groups or aggregations, especially during mating season.
- These sharks sometimes tolerate the presence of remoras (suckerfish) that attach to their bodies and feed on parasites.
- Despite their size, nurse sharks are generally docile and non-aggressive towards humans, making them popular with divers and snorkelers.
- Nurse sharks have relatively small eyes compared to other shark species
Do Nurse Sharks attack humans?
Unlike the more aggressive shark types, Nurse sharks are gentle and do not attack a swimmer unless they are provoked or harmed.
Has Nurse Sharks killed anyone?
So far, the recorded number of Nurse Shark attacks is only 52 times. Even in those instances, the attacks or bites weren’t fatal.
Where can you find Nurse sharks?
Nurse sharks live in the Atlantic and Pacific waters at a depth of 3 to 250 feet. So there is a good chance you will find them in coral reefs and shallow waters around these parts. If you do, be sure to stay harmless, non-provocative, and kind.
Where can I swim with Nurse Sharks?
You can swim with Nurse Sharks at Compass Cay Marina on a Bahamas Day Tour. The Nurse sharks here are accustomed to seeing visitors and swimming with them. Remember to keep your space and not provoke them.
How can you identify a Nurse Shark?
Nurse sharks are generally mellow-looking and can be easily told apart by the barbells that grow below their mouth and their round (instead of sharp) dorsal fins. They would usually be seen lazing around in the underwater sand beds, and coral reefs.
