Nurse sharks are the laziest animals

Nurse Shark Facts: It Replaces Teeth Every 20 days

The nurse shark (Ginglymostoma cirratum) is known as the “couch potato of the shark world” due to its sluggish lifestyle. It sleeps throughout the day and wanders over the sea floors and coral reefs at night, eating up small animals along the way. Here are 13 interesting facts about the nurse shark.

Nurse shark
Scientific name: Gentlymostoma Cirratum (means “curled, hinged mouth” and it refers to the puckered appearance of this shark)
Phylum: Chordata
Class: Chondrichthyes
Order: Orectolobiformes
Genus: Ginglymostoma

1. Nurse share are lazy

These fish have a slow metabolism and use very little energy. They spend all day resting and sleeping on the sea bed while other sharks must move to breathe. God gives them the ability to breathe by just pumping water over their gills. This species prefers to rest in crevices, ledges, and heaps of boulders.

Nurse sharks usually rest en masse, often in groups of 2 to 40 individuals. They cuddle and embrace each other inside the group, occasionally stacking on top of one other. According to scientists, this could be a form of social behavior.

Some of the other laziest animals in the world related articles are below:

A group of nurse shark sleeping each other

As the nocturnal animal, they hunt and feed at night alone.

They have strong location loyalty, which is regarded to be typical of Reef sharks. This type of shark frequently returns to the same mating areas again and again.

2. They use “buccal pumping” method to breathe

For some certain sharks, sleeping on the seabed is impossible. Great white sharks and whale sharks have to swim continuously to breathe. Because when they move, water consistently flows into their mouths and throughout their gills, delivering oxygen along the way. If the fish stop swimming for an extended time, the flow stops and they die.

However, this’s not true for the nurse shark. The species can fully breathe while staying still with a buccal pumping technique. They actively suck water into their mouth to bring oxygen to the gills. Well, I guess the lazy one always has his own way.

They can “walk” across the bottom with their pectoral fins, instead of swimming.

3. They eat food by sucking up

Nurse sharks are opportunistic predators, spending the majority of their time searching through the bottom sediments for food. On their face, there are 2 little knobs which are also known as barbels. Thes barbels are fleshy sensory organs with taste buds that they drag across the sand to find prey.

Because having small mouths, these creatures can’t eat large fish. Their diet mainly includes small prey, such as tunicates, crustaceans, mollusks, and other fish such as marine snails, sea urchins, shrimps, crabs, bivalves, spiny lobsters, squid, octopuses, and stingrays. They have also been observed grazing on algae and coral.

Despite the small mouths, these sharks have large throat cavities that create a tremendous suction that draws prey up into their mouth. They can generate sucking forces that are some of the strongest ever reported for any aquatic vertebra.

When the prey is too big for its mouth, the fish furiously shakes it to rip it up or utilizes a suck-and-spit method to tear it apart. Once caught, prey is crushed and ground by their powerful jaws and serrated teeth.

Nurse sharks unconsciously create a slurping or sucking sound while sucking, which makes many people mistake for that of a nursing baby.

The mouth functions similarly to a dental conveyor belt, with new rows of teeth appearing towards the back and gradually pushing older ones forward until they drop out. The length of an individual row is determined by the season. They will grow a new row of teeth every 10 to 20 days throughout the summer. However, in the winter, they need 50 to 70 days to have a new one.

There are not many nurse sharks’ predators, however other large sharks do prey on them on occasion.

A nurse shark uses its own body to create a fake refuge for crustaceans. Once they are within the trap, the nurse shark effortlessly gathers and consumes them.

4. Habitat

The nurse shark is a big shark species in the Ginglymostomatidae family. They are bottom dwellers found in tropical to warm temperate regions in the Eastern Pacific and Western Atlantic Oceans. You can find them from Cape Verde to Gabon in the Atlantic Ocean’s east, and from Rhode Island to Southern Brazil in the Atlantic Ocean’s west.

They can also live in the Eastern Pacific Ocean, from Baja California to Peru. Their juveniles can be on the bottom of seagrass flats and coral reefs at depths ranging from 3 to 75 meters. While the adults are in deeper reefs and rocky areas at night, at a depth of about 20 meters.

5. They have different colors

Adult nurse sharks have a slight color change from the young. They are typically light tan to dark brown. They can also be grey or yellowish. On the other hand, the juveniles have black dots covering their bodies, with a lighter coloring area surrounding each black spot. These dark stains tend to diminish over time.

In 1992, near Key Largo, Florida, a photographer took a picture of a “milk white” nurse shark with brown splotches. The fish could have been piebald, a hereditary trait related to albinism. Piebald animals have typically pigmented skin with patches of pigment-deficient white skin.

6. They are huge

Female nurse sharks are quite bigger than the males, with a size of 2.2 to 2.7 meters in length and a weight of 75 to 105 kilograms. This species can grow to a maximum length of 3 meters while the biggest one weighed 119.6 kilograms. The day-old pups weighed around 119 – 150 grams and have a length of 20 – 30 centimeters.

You can identify a nurse shark by some of its unique characteristics:

  • Mouth: blunt, with nasal barbels on both sides.
  • Eyes: small, many people believe they are blind and cannot see.
  • Dorsal and anal fins: broadly rounded.
  • The first and second dorsal fins: the size is comparable.
  • There is no conspicuous lower caudal fin lobe or interdorsal ridge.

7. Where do nurse sharks get their name?

Why is this fish called a nurse shark? There is a theory about this. That is a linguistic puzzle, but historians have theories. Suction-based feeding procedures may have reminded sailors of breastfeeding infants. Alternatively, the word “nurse” in nurse shark could come from “huss,” an antique term for an unrelated family of sea creatures.

Huss grew into nuss over time, which came to imply “shark” or “big fish.” So the nurse shark moniker could be a perversion of nuss.

8. They’re related to the whale shark

Whale sharks (fully matured) are the biggest fish reaching lengths of 12 meters and weighing several tons. These fish and nurse sharks have many in common.

They belong to the order Orectolobiformes, which includes 39 shark species found primarily in warm and tropical oceans. Animals in this order exhibit distinctive patterns on their skin, except for mature nurse sharks.

Whale shark also eat by sucking up food

Both nurse sharks and whale sharks have two dorsal fins and five pairs of gill slits on their backs, and barbels on their faces. They all feed by sucking prey and are called “carpet sharks” because of their small mouths which cannot expand behind the eyes.

Facts: There is the oddest member of Orectolobiformes which is the shaggy wobbegong shark. To catch prey, they lie stationary on tropical sea floors and use spectacular camouflage to attack them from below.

9. They don’t migrate

Most sharks do their migrations. Every summer, whale sharks from all over the Atlantic migrate to Mexico’s Yucatan Peninsula; Pacific great white sharks make winter journeys to a mystery mid-ocean location known as the “White Shark Café.”

On the other hand, nurse sharks are too lazy to do this. They like to stay in the same geographic location all year. To adjust to the cold, they become less active. Others, however, migrate to other sites in between breeding seasons. This makes them be classified as “partially migratory.”

10. One female can mate with multiple males

Female nurse sharks achieve sexual maturity between the ages of 15 and 20, while this age in the male is 10 to 15. Their mating season lasts from May to July.

To reproduce, the male biting the female on her pectoral fins to keep her in the right posture. If the female doesn’t feel like it, she will swim to shallow waters and cover her fins in the sand.

However, things are not always that smooth. A determined male would pursue the female and even organize a group with other males to cut off her path until it can bring her into the mating position. With this posture, the male can insert his clasper more easily towards the female’s cloaca.

Females will mate with many males during the breeding season. Sometimes, one female has to mate with 2, 3, or even more males at the same time. This can cause numerous scars on the female.

Nurse sharks are ovoviviparous, which means that the eggs grow and hatch inside the female’s body; and the female will give birth. They will experience a 6-month gestation and give the litter of 20 – 28 pups. A single litter of newborn pups may contain the children of up to six different fathers. After giving birth, the mother will not mate again for 18 months.

The newborn pups are roughly 30 centimeters long. Those pups will fight with each other to survive; the large ones will eat the smaller ones. As a result, only a small percentage of them reach maturity. The lifespan of nurse sharks live captivity is 25 years, but they can live 35 years in the wild.

11. They can be dangerous

Nurse sharks are slow and unaggressive. When they notice humans approaching, they normally swim away. Many individuals who swim or dive in the fish’s natural habitat believe they are harmless and not dangerous.

When scared, provoked, or mistaking your arm or finger for food, nurse sharks will attack and bite with a powerful vice-like grasp. In rare situations where the bites were deep, only medical devices could separate the jaw from the victim’s body.

Nurse shark's teeth can crush clam

These fish can crush clams and create enough suction to tear a matured conch out of its shell. They can hurt you with their exceptionally strong jaws that are loaded with thousands of small, serrated teeth.

There are many victims of this fish. In 2016, a 23-year-old swimmer in Boca Raton, Florida was clamped down on her right arm by a 61-meter-long-nurse-shark. In 2018, an Instagram model was attacked while posing in nurse shark-infested shallows. Fortunately, there is no record that this fish can kill humans.

12. Types of nurse sharks

Nurse sharks are worldwide carpet sharks of the Ginglymostomatidae family. There are 3 genera in this family, each genus has 1 species.

– The largest species, known as the nurse shark (Ginglymostoma cirratum), can grow up to 4.3 meters long and weigh up to 110 kg.

– The smaller one is the tawny nurse shark (Nebrius ferrugineus) with a length of 3.2 meters.

– The smallest species is the short-tail nurse shark (Pseudoginglymostoma brevicaudatum). They just grow 75 centimeters in length.

The short-tail nurse shark

The grey nurse shark does not belong to the Ginglymostomatidae family. Because of their name, they are frequently confused with the nurse shark or the tiger shark. They are, however, sand tiger sharks (Carcharias taurus), spotted ragged-tooth sharks, or blue-nurse sand tiger sharks.

They inhabit the continental shelf, at sandy shorelines or hidden reefs at depths of up to 191 meters. They can be found in the oceans off the shores of South Africa, the east coasts of North and South America, Australia, and Japan.

The grey nurse shark is endangered by fishing activities and accidental capture by amateur divers. On Australia’s east coast, there are less than 1000 left.


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