Tawny nurse shark

What it is

This species belongs to the carpet shark family and is the sole living member of its genus. It has a robust, cylindrical body with a broad, flattened head. The skin colour ranges from yellowish to reddish or greyish brown above, with a pale underside. Distinctive features include narrow, sickle-shaped pectoral fins and pointed dorsal fin tips. These traits help distinguish it from the Atlantic nurse shark. Adults can reach lengths of 3.2 metres. The shark possesses small eyes with prominent ridges and long barbels near the nostrils. Its teeth are fan-shaped with sharp central points, arranged in overlapping rows.

Where it lives

The tawny nurse shark inhabits coastal waters across the Indo-Pacific region. Its range extends from South Africa and the Red Sea eastward to India, Southeast Asia, and northern Australia. In the Pacific, it occurs as far north as Japan and China, and east to islands like Tahiti and Samoa. Fossil evidence suggests it once lived in the Atlantic Ocean. This inshore species prefers sandy flats, seagrass beds, and coral reefs. It is found from very shallow surf zones to depths of 70 metres, though it is most common between 5 and 30 metres.

How it lives

These sharks are primarily nocturnal hunters but may be active during the day in some regions. During daylight hours, they rest in caves or under ledges, often in large groups stacked together. They have small home ranges and return to the same spots daily. Their diet specialises in octopus, which they extract from crevices using powerful suction. They also eat crustaceans, small bony fishes, and occasionally sea snakes. Natural predators include bull sharks and great hammerheads. Parasites such as tapeworms can infest their digestive systems.

Breeding and life cycle

Reproduction is aplacental viviparous, meaning embryos hatch from egg capsules inside the mother. This species is unique among carpet sharks because its embryos practice oophagy. After exhausting their yolk supply, the developing young feed on eggs produced by the mother. This results in large newborns, with litter sizes typically limited to one or two pups. Mating occurs around July and August in some areas. Males mature at about 2.5 metres, while females mature between 2.3 and 2.9 metres.

Fish and people

Commercial fisheries catch this shark for its meat, fins, liver oil, and leather. It is targeted in countries like India and Thailand but is mostly bycatch in Australia. Anglers value it as a game fish due to its strength and habit of spitting water at captors. The species adapts well to captivity and is displayed in public aquaria. While generally docile towards divers, it has powerful jaws and can bite if provoked. Ecotourism operators use them as attractions in places like Thailand and the Solomon Islands.

Status and threats

The International Union for Conservation of Nature lists this species as Vulnerable globally. Heavy fishing pressure and low reproductive rates hinder population recovery. Habitat degradation and destructive fishing practices, such as using explosives, threaten local populations. Declines have been recorded in India and Thailand. However, the Australian subpopulation is considered of Least Concern because it is not heavily targeted there. Some individuals exhibit physical abnormalities, such as missing dorsal fins, possibly linked to environmental stress.

Relatives and look-alikes

It is closely related to the nurse shark of the Atlantic and East Pacific. Both belong to the same family of carpet sharks. The tawny nurse shark is distinguished by its sickle-shaped pectoral fins and pointed dorsal fins. Phylogenetic studies place its genus as a sister to the nurse shark genus. Other relatives in the broader clade include the whale shark and zebra shark. It is sometimes confused with the nurse shark due to similar general appearance.

Questions people ask about Tawny nurse shark

Good reading and sources

• Tawny nurse shark on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data