Ginglymostomatidae facts for kids
Quick facts for kids Ginglymostomatidae |
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| Ginglymostoma cirratum | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Order: | Orectolobiformes |
| Family: | Ginglymostomatidae T. N. Gill, 1862 |
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Ginglymostoma |
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The Ginglymostomatidae are a family of carpet sharks known as nurse sharks. You can find these sharks all over the world in shallow, warm waters near the coast. They are slow-moving and calm sharks that spend their time on the ocean floor. In fact, they are one of the most common types of sharks you'll find in shallow coastal areas! Nurse sharks usually only bother people if they feel threatened.
The name "nurse shark" might come from an old word, nusse, which was once used for catsharks. The scientific family name, Ginglymostomatidae, comes from two Greek words: ginglymos (meaning "hinge") and stoma (meaning "mouth"). This probably refers to their unique mouth shape!
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What Do Nurse Sharks Look Like?
Nurse sharks come in different sizes, from quite large to fairly small. They are usually yellowish to dark brown.
Nurse sharks have strong, muscular pectoral fins (the ones on their sides). They have two dorsal fins (on their back), but these don't have spines. The second dorsal fin is smaller and lines up with their pelvic and anal fins (on their underside). Their tail is quite long, making up more than a quarter of their total body length!
The mouth of a nurse shark is very distinctive. It's located way in front of their eyes, almost under their nose. This position helps them find food on the ocean floor. On their lower jaw, they have two fleshy whiskers called barbels. These barbels are like super-sensitive feelers that help the nurse sharks sniff out prey hidden in the sand or mud.
Behind each eye, you'll see a very small, round opening called a spiracle. This is part of their breathing system. Nurse sharks have fan-shaped teeth with serrated (saw-like) edges. Just like other sharks, they constantly replace their teeth throughout their lives.
How Big Are Nurse Sharks?
The biggest species, simply called the nurse shark (Ginglymostoma cirratum), can grow up to 4.3 m (14 ft) long. That's about as long as a small car! It can also weigh up to 110 kg, which is heavier than a large person.
The tawny nurse shark (Nebrius ferrugineus) is a bit smaller, reaching about 3.2 m (10 ft). The smallest of the group is the short-tail nurse shark (Pseudoginglymostoma brevicaudatum), which is only about 75 cm (2.46 ft) long.
Behavior
Nurse sharks are nocturnal, meaning they are most active at night. During the day, they often rest in large groups of up to 40 individuals. They like to hide under submerged ledges or in cracks within coral reefs. It seems they have favorite resting spots and will return to them every day!
What Do Nurse Sharks Eat?
At night, nurse sharks usually hunt alone. They spend most of their time searching through the sand and mud on the ocean floor for food. Their diet mainly includes crustaceans (like crabs and lobsters), molluscs (like clams and snails), tunicates (sea squirts), and other fish, especially stingrays.
Nurse sharks are clever hunters. They can suck in their prey using their large throat cavities like a vacuum cleaner! This helps them catch fish that might otherwise be too fast for them. Even though their mouths are small, this "suction" method allows them to grab their meals. They have also been known to munch on algae and coral.
How Do Nurse Sharks Reproduce?
The mating season for nurse sharks typically runs from late June to the end of July.
All nurse sharks are aplacental viviparous. This means the eggs develop and hatch inside the female's body. The baby sharks then continue to grow inside her until they are born live. The pregnancy lasts about six months, and a typical litter (group of babies) has 30 to 40 pups.
Female nurse sharks usually mate every two years because it takes about 18 months for their bodies to get ready to produce another batch of eggs. When they are born, young Ginglymostoma cirratum nurse sharks are already fully developed and about 30 cm long. They have a spotted pattern on their skin, which fades away as they get older.
Types of Nurse Sharks
Here are the different groups (genera) and species of nurse sharks:
- Genus Ginglymostoma J. P. Müller & Henle, 1837
- Ginglymostoma cirratum Bonnaterre, 1788 (the common nurse shark)
- Ginglymostoma unami Del-Moral-Flores, Ramírez-Antonio, Angulo & Pérez-Ponce de León, 2015
- Genus Nebrius Rüppell, 1837
- Nebrius ferrugineus Lesson, 1831 (the tawny nurse shark)
- Genus Pseudoginglymostoma Dingerkus, 1986
- Pseudoginglymostoma brevicaudatum Günther, 1867 (the short-tail nurse shark)
See Also
- List of sharks
