GINGLYMOSTOMATIDAE NURSE SHARKS
The largest species is the Nurse shark Ginglymostoma cirratum, and could possibly reach 14 feet long and up to 243 pounds. The Tawny Nurse shark Nebrius ferrugineus has been recorded up to 10 feet long and the smallest is the Shorttail Nurse shark Pseudoginglymostoma brevicaudatum at under 3 feet long.
Nurse sharks are yellowish to dark brown in color. Their head is flattened and broad. There are no lateral skin flaps. The snout is rounded or truncated. The mouth is transverse and subterminal in front of the eyes. The serrated teeth are fan-shaped and independent. There are long, nasoral grooves. The nostrils have barbels. The eyes have small spiracles behind them. The gill slits are small. The 5th gill slit almost overlaps the 4th gill slit. There are 2 spineless dorsal fins. The second one is level with, and about the same size as the anal fin. The latter is close to the lower caudal fin. The precaudal tail is much shorter than the head and the body. The caudal fin is elongated with a strong terminal lobe and subterminal notch, but with no ventral lobe, or a very short ventral lobe. The pectoral fins are muscular. They are un-patterned or have a few dark spots when they are young.
They can be found in subtropical and tropical continental and insular waters. They can be found over coral and rocky reefs, reef lagoons, sandy areas and mangrove keys. They are found in the intertidal and surf zones to at least 230 feet. Sometimes they are barely covered.
Ginglymostomatidae are ovoviviparous. The genus Pseudoginglymostoma haven’t been confirmed, but more than likely they are ovoviviparous as well. In some, the mating season runs from late June to the end of July. It is suggested that the gestation period is 6 months. Some litter sizes can be between 30–40 pups. The mating cycle is thought to be biennial, taking 18 months for the female’s ovaries to produce another batch of eggs. In the common Nurse shark or Ginglymostoma cirratum young are born around 30 cm/11.8 inches long.
They are nocturnal. Nurse sharks are social and rest on the bottom in small groups. Check out this video of Nurse shark social feeding behavior here. They cruise and clamber on the bottom with their mouths and barbels close to the bottom searching for food. They are high on the RSI having short mouths with large cavities that suck in a variety of bottom invertebrates and fish. Check out this video to see their mouths and barbels.
The larger species were or are common. They are often caught in local inshore fisheries for food, liver oil, and even tough leather. There have been some local extirpations reported. Ginglymostoma and Nebrius are common and hardy and can survive well in captivity and large aquaria. They are not typically aggressive, but can do some harm if provoked. They have been known to bite hard and hang on. Nurse sharks are popular in dive tourism or ecotourism.
Genus Ginglymostoma (J. P. Müller & Henle, 1837)
Genus Nebrius (Rüppell, 1837)
Genus Pseudoginglymostoma (Dingerkus, 1986)