page_title: Nervous shark
section_title: Biology and ecology
hierarchical_section_title: Nervous shark / Biology and ecology
caption_attribution_description: English: Cerberus schneiderii. Male (USNM 573675, SVL 598 mm, TL 756 mm) from a rice paddy in the Baucau area, Baucau District.
context_page_description: The nervous shark is a species of requiem shark, and part of the family Carcharhinidae, so named because of its timid behavior in regard to humans. It is common in shallow, coastal waters off northern Australia, Papua New Guinea, and the Solomon Islands. A small brownish or grayish shark typically measuring 1.0–1.3 m long, this species has a short, blunt snout, oval eyes, and a relatively large second dorsal fin. The leading margins of most fins are finely edged with black, and the lower caudal fin lobe is black-tipped.
  Small bony fishes are the main prey of the nervous shark, while crustaceans, molluscs, and snakes may also be eaten. It is viviparous, with the developing embryos nourished through a placental connection. The details of its life history seem to vary depending on latitude—for example, the timing of the breeding season and the length of the gestation period. Females produce litters of one to six young either annually or biennially. The harmless nervous shark is caught incidentally by coastal gillnet fisheries and perhaps also by line and trawl fisheries. The International Union for Conservation of Nature has been listed under Least Concern.
context_section_description: The diet of the nervous shark consists mainly of small teleost fishes (including silversides, smelt-whitings, wrasses, and grunters). Crustaceans (including prawns, crabs, and mantis shrimps) and molluscs (predominantly cephalopods but also bivalves and gastropods) constitute secondary food sources. This shark is also known to occasionally prey on the semiaquatic snakes Cerberus rynchops and Fordonia leucobalia. A known parasite of the nervous shark is the myxosporean Kudoa carcharhini.
  Like other requiem sharks, the nervous shark is viviparous: once the embryos exhaust their initial supply of yolk, they are provisioned by the mother through a placental connection formed from the depleted yolk sac. Adult females have a single functional ovary, on the right, and two functional uteruses. The male bites at the sides of the female as a prelude to mating. After mating, the female stores the sperm for approximately four weeks prior to fertilization. In Darwin Harbor, mating occurs from January to March and birthing occurs in October and November following a gestation period of eight to nine months. In Shark Bay, mating occurs from late October to early November and birthing occurs around the same time the following year, following a gestation period of 11 months; this slower development likely reflects the cooler temperatures of Shark Bay.
  Females produce litters on an annual cycle in Darwin Harbor and on a biennial cycle in Shark Bay. The litter size ranges from one to six and is not correlated with the size of the female. The newborns are relatively large, measuring 35–40 cm (14–16 in) long, and are birthed in shallow nursery areas such as Herald Bight in Shark Bay. The juvenile growth rate is high for a shark; males and females mature sexually at around 84 and 91 cm (33 and 36 in), respectively, in Darwin Harbour, and 91 and 101 cm (36 and 40 in), respectively, in Shark Bay. The age at maturity is around four years for males and six years for females; the maximum lifespan is at least 12 years for males and 16 years for females.
caption: The snake Cerberus rynchops is sometimes eaten by the nervous shark.
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