Latin name

Nebrius ferrugineus

Other name

Nebrius ferrugineus

Identification

The body shape of the tawny nurse shark is more streamlined than that of other nurse sharks. The body is compact and cylindrical. The head appears narrow, U-shaped from above and below. The snout is wedge-shaped from the side, moderately elongated. The eyes are small, with protrusions above the eyes and small spiracles behind. The mouth is small, the upper lip is divided into 3 lobes. Five gill slits are located on the sides and are clearly visible from above and below. The fourth and fifth pair of gill slits are closer together than the others. There is a pair of antennae in front of the nostrils. The spiral valve of the intestine has 23-24 turns. The teeth are arranged in a shingle-like pattern in the jaw. There are 29-33 in the upper jaw and 26-28 in the lower jaw. The number of active tooth rows on each jaw is 2 to 4. Each tooth has many weakly divided apices, with the lateral apices well developed (comparable to the central one). The root has a V-shaped appearance (when viewed from below). The ratio of tooth thickness and width to height increases with age, and the relative size of the central denticle increases. Sharks of the genus Nebrius are not difficult to distinguish by tooth shape and arrangement from sharks of the closely related genus Ginglymostoma, whose teeth are not arranged in a tile-like pattern and only one apex is well developed on each tooth.

Features of fish fins

The pectoral fins are narrow and crescent-shaped. Their anterior margins are approximately opposite the fourth pair of gill slits. The anterior margin of the dorsal fin is slightly forward of the anterior margin of the pelvic fins. The dorsal fins are triangular. The second dorsal fin is conspicuously smaller than the first and almost as large as the anal fin. The caudal fin makes up about a quarter of the shark's total length. Many tawny nurse sharks off the coast of Japan, Taiwan and the Ryukyu Islands lack a second dorsal fin. It has been suggested that this anomaly is caused by pregnant females staying in water with increased salinity and/or temperature due to anthropogenic disturbance. 

Fish colouring

Tawny nurse shark color is reddish, brownish, reddish, lighter underneath, darker on top (to dark grayish brown). No spots or stripes.

Distribution

In the Indian Ocean, distributed along the coast of Africa from the south of the continent to the Red Sea, as well as near Madagascar and other islands. Occurs in the Persian Gulf, waters off India, the Maldives, Southeast Asia, including Malaysia and Indonesia, and waters north of Australia. In the Pacific Ocean, it is found from southern Japan to northeastern Australia, as well as near some islands in Oceania. 

Habitat

A tropical marine species. The usual depth of its habitat is from 5 to 30 m. Occurs on continental and island shelves, from the intertidal zone to depths of at least 70 m. Settles on or near the bottom in lagoons or along the outer edges of coral and rock reefs, on sandy areas near reefs and near sandy beaches.

Size

The normal length of adult sharks is about 2.3-2.5 meters, with a maximum length of 3.2 meters. 

Behavior

The more streamlined body shape compared to other nurse sharks suggests that these sharks are active swimmers. The body, head, fins and teeth of these sharks are comparable to those of the agile reef sharks that share their habitat. Tawny nurse sharks are nocturnal. They rest in shelters during the day and slowly patrol the reefs at night, although some individuals are active during the day. This is the behavior of the sharks that live off the coast of Madagascar. In captivity they also become active when fed during the day. During the daytime rest they gather in schools of up to 30 or more individuals and rest on the sandy bottom, in caves or crevices of rocky and coral reefs in shallow waters. Sharks lie close together or even on top of each other. They prefer a particular, once selected, shelter and return to the same cave or crevice each day after a night hunt.

Food and feeding habits

The diet consists of crabs, lobsters and other crustaceans, octopus, squid, sea urchins, various bony fish such as surgeonfish, mackerel, shiners and sometimes sea snakes. While feeding, these sharks explore crevices, holes and depressions in the reef. If they find food beyond the reach of their teeth, they suck it sharply into their large mouths. The stomachs of captured Nebrians have been found to contain small mobile fish, which the sharks apparently sucked at night when they were resting in the shelter, as such prey would easily escape pursuit during the day. 

Reproduction

They reproduce by egg-laying. A litter contains 1 to 4 newborns about 60-78 cm long. In the uterus of pregnant females caught off Okinawa, 1 or 2 developed embryos ranging in length from 29.7 cm to 59.5 cm have been found. In embryos longer than 33.8 cm, the yolk sacs were reabsorbed and the highly inflated stomach was filled with yolk material. In addition, there were large egg capsules in the uterus. Oophagy is apparently characteristic of this shark species. Embryos eat unfertilized eggs. It is not known if Neebrium shark embryos eat each other. The egg capsules of the tawny nurse shark are bulbous and enclosed in a thin translucent brown capsule. The breeding season off the coast of Madagascar lasts from July to August. Adult females have one functional ovary and two functional uteruses. Males and females reach sexual maturity at a length of 250 cm and 230 cm, respectively.

Fishing

This species is targeted. They are caught in South and Southeast Asia (and probably elsewhere) for meat, liver, skin, fins, etc. They are a target fishery. The subject of sport fishing. Captured sharks may spit water in the fishermen's faces and grunt in between. Whether they are intentionally targeting their enemies is unknown. In addition, once caught on the hook, sharks actively resist and struggle, making them difficult to handle.

Relationship with a person

Tawny nurse sharks are virtually harmless to humans. They are attractive to recreational divers. They will usually allow you to play with them, but if provoked they may bite. These sharks do well in captivity and are kept in many public aquariums and oceanariums where they are tame enough to be hand-fed.