Species Profile For the Grey Nurse Shark
Common Name: Grey Nurse Shark ( NOTE: Do not confuse with the Nurse Shark, they are different!)
Scientific Name: Genus:Carcharias Species: taurus
Alias: Sand-Tiger Shark, Ragged-Tooth Shark, Ground Shark, etc.
Size at birth: Grey Nurse pups generally measure in at around 39 inches (99 cm) at birth, though some have been recorded significantly smaller (believed to be becuase of a large litter), and some have been recorded larger (this believed to be from intrauterine cannibalism, and is generally present (babies being bigger)when litters result in low numbers, which further signals cannibalism).
Average Adult Size: Average size ranges from 5-9 feet, though it is typically seen in the wild at a length of around 8-10 feet.
Maximum Recorded Adult Size: Grey Nurse Sharks have a maximum length believed to be around 10.5 feet (320 cm) in females and 9.9 feet (301 cm) in males.
Recorded Adult Weight: These sharks are, believe it or not, one of the lighter sharks out of the large species. Length for length, Grey Nurse Sharks are def. in the feather-weight category, weighing in at an average between 250lbs.-273lbs. But there have also been rare records of huge Grey's comming in at over 320lbs., so until we are able to devote more research on these guys, we can only go off of what has been recorded thus far.
Size & Age of Sexual Maturity: Male maturity is reached at approx. 6.3 feet (190-195 cm). Female maturity is reached at usually over 7.2 feet (220 cm) in total length. Grey Nurse Sharks may reach sexualy maturity as early as 4-5 years of age in the wild (for males), but in captivity, it seems as this slows and some don't reach sexual maturity until 5-7 years old. Female sexual maturity has been observed in the wild as having taken place as early as 5-6 years, but once again in captivity it has been noted as taking up to nearly 9 years of age before a sucsessful mating would occur.
Growth Rate: Grey Nurse's grow at a rate of about 0.6 to 2.9 cm per month (or 7 to 35 cm per year). And growth slows significantly once sexual maturity is reached.
Distinctive Features: - This large shark has a short, pointed snout, small eyes, protruding spike-like teeth and small, equally-sized dorsal and anal fins with the first dorsal fin closer to the pelvic than to the pectoral fins. The caudal fin has a pronounced subterminal notch and short ventral lobe.
Longevity of species: Individuals in aquariums have lived to be 16+ years old, but it is estimated that they live much longer, beyond 30+ years.
Breeding: Embryonic development with a Grey Nurse Shark is ovoviviparous with ovophagy and embryophagy occurring in the uteri. Usually only one pup survives in each uteri (Grey Nurse Sharks have two uteruses) since the largest embryo sometimes ends up eating all of its smaller siblings during gestation. This generally limits litter sizes to two individuals. At 6.7 inches (17 cm) embryos have functional teeth and are beginning to try to feed, and at 10.2 inches (26 cm) they are able to move and eat in utero. Gestation periods are believed to be around eight to nine months long and females only produce fertile eggs every other year (Biennial), so re-population is slow.
Coloring/Markings:Grey Nurse Sharks are countershaded, the dorsal (upper) part is dark, mostly a grey to bronzy colour whereas the ventral (lower) part of the body is pale. Juveniles have reddish or brownish spots on the posterior (back) half of the body and tail. These spots often fade as the shark ages, but are sometimes still visible on adults.
Geographical Distribution: Grey Nurse Sharks have a broad inshore distribution, around the main continental landmasses. In Australia, Grey Nurse Sharks have been regularly reported from Mooloolaba in southern Queensland, around most of the southern half of the continent (excluding the Great Australian Bight), and northward to Shark Bay in Western Australia. The Grey Nurse has been recorded as far north as Cairns in the east, the North West Shelf in the west and also in the Arafura Sea.
Habitat: Grey Nurse Sharks, love to hang out just above the sea bed and in or near deep sandy-bottomed cannals or rocky caves, usually in the vicinity of inshore rocky reefs and dense islands.
Diet: The diet of the adult Grey Nurse Shark, much like that of the Nurse Shark, consists of a wide range of fish, snails, squids, crabs, bivalves, clams and lobsters, to include on occasion other small sharks.
Activity level: During the day, they are generally found in the vicinity of dropoffs, caves and ledges. They spend their days mostly in the shadows. At night however, they hunt their victims maticulously, using their habitat to their advantage, raiding coral reefs rich with inverts., fish and the occasional other shark. As an overall average, the majority of any substantial activity takes place when the sun goes down.
Preferred Water Temperature & Conditions: Primarily in subtropical to cool temperate waters, but are also noted in warmer tropical waters (ususally associated with migratory routes).
Shark in Captivity: The Grey Nurse Shark is NOT a species suitable for the home aquaria. Their size, in addition to known aggressiveness, and high maintenance requirements keep this shark as one much better suited for public aquariums. The Grey Nurse is a very common shark exhibited in public aquariums, and is usually kept in large exhibits which include other large sharks as tank mates. A single adult Grey Nurse requires a tank with a depth of at least 13.1 ft (4 meters), with a footprint of 2,000-2,300 sq. ft and 195,000-225,000 gallons.
Conservation: The Grey Nurse Shark is listed as two separate populations under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). The east coast population is listed as critically endangered and the west coast population is listed as vulnerable. This species became the first protected shark when the NSW Government declared it a protected species in 1984. Grey nurse sharks are now protected under fisheries legislation in NSW, Tasmania and Queensland and Western Australia. Globally, the species is listed as Vulnerable in the IUCN Red List of Threatened Animals.
Other Notes/Special Requirements: The Grey Nurse are a big shark that require fairly deep waters, often found near ship wrecks. Also this species is generally considered a protected species, making unavailable to private individuals. Also this species requires tanks that are at least the size of small Public Aquariums - at least 195,000 gallons.