Wednesday, December 1, 2010

10 Facts about nurse sharks

During the past weeks we have been very lucky to see nurse sharks in Tayrona Park, so lets talk about them.

  1. The scientific name for the nurse shark is Ginglymostoma cirratum which means “curled, hinged mouth.”
  2. They are nocturnal, hunting alone at night, and resting during the day in large groups up to 40 sharks, sometimes piled on top of each other.
  3. Nurse sharks can be huge - up to 14 feet and a weight up to 330 pounds.
  4. They are often observed at depths of a meter or less within the intertidal zone, though they are known to range down to depths of at least 12 meters. This species is often found along reef sites, within mangrove channels, and on sand or seagrass flats.
  5. Nurse sharks re carnivorous, primarily feed on benthic invertebrates (i.e. spiny lobsters, shrimps, crabs, sea urchins, squids, octopuses, marine snails and bivalves) and benthic fish (i.e. sea catfishes, mullets, puffers and stingrays). The smallish mouth and large bellows-like pharynx of the nurse shark allow this species to inhale prey items with tremendous force and speed.
  6. They are also known as cat sharks, due to their barbells - fleshy appendages which hang below their nostrils and, in part, provide a sense of touch which assists in the location of prey along the bottom
  7. Unlike most sharks, which require constant motion to move water over their gills and maintain a sufficient internal blood pressure, the nurse shark often remains motionless along the bottom - actively pumping water over its gills through the continual opening and closing of its mouth.
  8. They are gray-brown in color and their distinctive tail fins can account for up to a quarter of their length. Unlike other sharks, nurse sharks are smooth to the touch.
  9. Nurse sharks are ovoviviparious, meaning their eggs develop and hatch inside the female’s body, where the hatchlings continue to grow until live birth occurs. Gestation is six months, and a typical litter size is 21 to 28 pups.  Nurse sharks reach maturity at about 15 to 20 years of age. Their average life span is 25 years.
  10. Nurse sharks are found in the warm, shallow waters of the western Atlantic and eastern Pacific oceans. 
 And another video of a nurse shark trapped by a ring.

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