Nurse Shark

Next week is Labor Day weekend, and I will be taking a short break from Next Door Zoo. Read at the end of the article for more details.

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The nurse shark is an odd-looking fish, quite different from what most people think of when they hear the word “shark.” This fish is smaller than most sharks, slower, and shaped differently than the infamous great white shark. Their pectoral fins, the ones on the side of their body, are used to help the shark “crawl along the sea floor. It is unknown exactly where the nurse shark’s name came from. Their scientific name ( Ginglymostoma cirratum) translates from Latin as “The shark with the flexible curly mouth.”

Size

These sharks, though usually kind of small, can grow to 15 feet (4 m) in length. Up to one-quarter of this length can be occupied by the tail alone! Average nurse sharks grow to be 7.5 to 9.75 feet (2.2-3 m) in length. Individuals of this size can weigh 200 to 330 pounds (90-150 kg).

Diet

Nurse sharks are nocturnal, so they eat at night. Their main food includes lobsters, shrimp, crabs, sea urchins, squid, and octopi. They also sometimes eat fish. Because it is nocturnal, it is easier for them to catch fish than it is for other animals to because fish are less active at night. The nurse shark has a small mouth and a large throat. Although a small mouth may seem like a hindrance as the shark can not eat large food, it actually helps them capture their prey. It can suck up water through its mouth, and because of its small size, the water will come in quickly. Nearby fish will be sucked up into ‘. By putting its mouth over crevices, it can suck prey out of its hiding place. They also use this technique to suck snails out of their shells.

Habitat and range

The range of this shark includes shores along the coast of western Africa and the Caribbean. It extends all the way to New England on North America’s east coast, but stops near the southern part of California on the west coast. It also goes about halfway down South America. These sharks are not pelagic, meaning they do not live in the open ocean. They do live in areas near shore. Coral and rocky reefs, mangroves, and sandy areas are all home to nurse sharks. They inhabit depths of 425 feet (130 m) to the surface.

Status and threats

The IUCN redlist has not classified this species due to data deficiency. The population in the Western Atlantic has been classified, however, and is said to be Near Threatened. Although this may sound severe, it is the ranking right below Least Concern. Being a shark, this fish has few natural enemies. Some of the known ones are bull sharks and tiger sharks. Humans catch these sharks for sport and for commerce. They are popular in aquariums; their hide is used for leather; their flesh is consumed by humans and used in fish meal, and oil is extracted from their livers. Coral reefs, which are common habitats for these sharks, are extremely vulnerable for pollution and disturbance from tourism.

Mating and young

Nurse sharks are one of the few sharks that have a well-studied mating ritual. The male swims alongside the female, bites lightly onto her pectoral fin (the one on the side), and rolls her over. The pair then mate. Often many males will try to breed with the same female. Females will often get many bite scars when this happens. The females will sometimes try to avoid males, or they will swim in shallow water where they can bury their pectoral fins in the sand, out of reach of the males. Nurse sharks can be oviparous or ovoviparous. The first means that the shark lays eggs that develop and hatch outside of the body. The second means that the eggs develop inside the body, and hatch inside or immediately after coming out of the body. The pups, as baby sharks are called, hatch from leathery eggs and spend their childhood on the ocean floor. One litter contains from 20 to 30 pups. When they are born, the pups are about one foot (30 cm) long, and they grow 4 to 6 inches (10-15 cm)  per year. This rate slows down as the sharks get older. Young nurse sharks do not start mating until 15 to 20 years of age. They can live up to 25 years in the wild.

Because next Saturday is Labor Day weekend, I’m taking a one-week break from posting articles. Spend some time with your family and friends or work on a project, whatever you want to do. I will be posting a special video on Facebook that day, so head on over and like Next Door Zoo on Facebook if you haven’t already! You’ll get links to these articles and more animal facts!

Don’t forget to scroll down and comment your guess about what the animal on September 12th is!

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Sources:

Photo Credits:

  • Nurse Shark – Public Domain
  • Mystery animal – Brian Gratwicke
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