Wednesday, August 8, 2012

The Nurse Shark

The Nurse Shark
       Ginglymostoma cirratum

The nurse shark is a common shark species. It poses no threat to humans unless harassed or threatened.

The nurse shark's most identifiable feature are it's conspicuous nasal barbels.
Color is variable, ranging from light yellowish to dark brown. The underside is a whitish-gray color. Neonatal nurse sharks have dark spots to aid camouflage.

 Another way to identify a nurse shark is by its caudal fin, which is almost completely an upper lobe.

Kingdom : Animalia
Phylum : Chordata
Subphylum : Vertebrata
Class : Chondrichthyes
Subclass :  Elasmobranchii
Order : Orectolobiformes
Family : Orectolobidae
Genus : Ginglymostoma
Species : cirratum

Similar Species and Other Family Members:
There are no similar species or any other species in the family.

Nurse sharks are an ovoviviparous. Male nurse sharks are sexually mature at 10 - 15 years, while females are sexually mature at 15 - 20 years. Nurse sharks give birth to 20 - 30 young about every other year. The gestation period is 5.5 months.

Males mature at 210 cm (7 feet), while females mature at 240 cm (8 feet). The maximum reported length is 430 cm (14 feet), but most experts agree that 430 cm is an exaggeration. A more realistic size estimate is 270 cm (9 feet).

The nurse shark feeds on crabs, lobsters, bivalves, squid, bottom-dwelling fish, octopus, shrimp, sea snails and sea urchins. They will also occasionally feed on stingrays. Most feeding is done at night, as nurse sharks often rest during the day.

Teeth & Jaws:
Here is an image of fossilized nurse shark teeth.

Habitat and Distribution:
Nurse sharks live on reefs and are found all throughout Atlantic reefs. They are found in tropical and sub-tropical waters of the east coast of the Americas and the west coast of Africa. This species is abundant all year long in Florida and the Caribbean.

Life Span:
The life span in the wild is unknown, but the oldest shark in captivity reached an age of 25 years.

Conservation Status:
According to the IUCN Red List of Threatened Species, the nurse shark is data deficient, meaning there is not enough data to determine a conservation status.

note: none of the images are mine