Creature Feature: Nurse Sharks

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  • By Melissa Johnson
Creature Feature: Nurse Sharks

You are gliding over the reef, your eyes scanning beautiful flashes of brightly colored fish and corals. Then suddenly you spot a shadow swimming towards you from the distance. Adrenaline rushes through your body, and you turn to signal your buddy with a hand sticking up on the top of your head. There is only one thing this means: shark! If you are anything like us, this is a feeling you crave.

 A shark sighting can quickly turn a dive from ordinary into extraordinary. At Force-E, sharks are one of our favorite animals to spot in the wild. Join us on Sept 12th for a “jawesome” presentation by Hannah Medd, founder of the American Shark Conservancy.

 

Of the sharks you are likely to encounter in local waters, Nurse Sharks are not only the most prominent, but also the most mellow. With their somewhat flattened body and broad, round head, they resemble a large catfish. Nurse sharks can actually use their pectoral, or front fins, to “walk” along the ocean floor. When mature, they are light grey or tan in color, with a white underbelly.

 

Image courtesy of Force-E Instructor Max Devine.

 

The scientific name for Nurse Sharks is Ginglymostoma cirratum, which references their facial structure, meaning, “curved, hinged mouth.” However, they would more accurately be known as the slackers of the sea.

 

Nurse sharks spend the majority of their day resting. They are usually snuggled up in a group, piled alongside each other under a ledge.

 

Image courtesy All Five Oceans.

 

Nurse Sharks are specially adapted to their lazy lifestyle. Most fish and sharks must keep moving to breathe, but Nurse Sharks remain resting and pump water through their mouths and gills.

 

They maintain their sedentary state year round and are one of the few species of shark that doesn’t migrate in the winter. Instead, they stay even more still and conserve their energy.

 

Nurse Sharks even hunt lazily. As nocturnal feeders, they chow down on fish, mollusks and crustaceans. By feeding at night, they are able to prey on slow-moving fish and target critters that are resting. Many sharks are “night owls,” and you can learn more about how their clever adaptations, movements and behaviors allow them to remain successful in the dark during our upcoming Sharks at Night presentation!

 

Image courtesy Force-E Photo Pro Nikole Heath.
 
To catch their food, nurse sharks quickly suck prey and water into their mouths. They can then filter out excess water, sand and silt and expunge it through their gills.

 

There is speculation that Nurse Sharks received their name from the distinct “sucking” sound they make when searching for prey. These sounds are similar to those made by infants. It is more likely, however, that “Nurse” evolved from the Old-English word “hurse,” which means “sea-floor shark.”

 

These bottom dwelling sharks are prominent throughout warm, shallow waters of the Atlantic, Caribbean, and eastern Pacific.

 

Most shark species are migratory. Dr. Stephen Kajiura joins us on Sept 26th to share pictures and details of his research tagging and tracking the migrations of local sharks. Nurse Sharks, however, stay true to their lazy ways. Instead of traveling to warmer waters, they merely move around even less.

 

Baby Nurse Shark image courtesy Force-E Instructor Jeff Nelson.
 
Nurse sharks are even slow breeders. They reach maturity around 15 – 20 years, and have only been recorded living up to 35 years. The sharks average pregnancy lasts 6 months, but females are unable to produce eggs again for 18 months after giving birth.

 

Nurse Sharks are ovoviviparous, since their babies develop within egg casings within the mother. Not all sharks share this trait. You can learn more and get your fill of adorable baby shark pictures during our Shark Babies presentation on Sept 27th.

 

Nurse sharks are one of our favorite species because they are such docile, unique creatures. Join us for a dive or snorkel with some nurse sharks on Nursery Reef in Pompano with the lead scientist from Sharks4Kids on Sept 18. Dr Derek Burkholder will be talking about sharks in general especially the nurse shark.

 

Do you have questions about Nurse Sharks? Comment below and we'll get you answers...

 

See you under water soon!