Bullhead Sharks (Family Heterodontida )

Family: Tribe Heterodontina Gray, 1851, List Fish British Mus., Pt. 1, Chondropterygii, British Mus. (Nat. Hist.): 65 (Family Squalidae).

Type Genus: Heterodontus Blainville, 1816. Raised to the rank of Family Heterodontoidae by Gili, 1862b, Ann. Lyceum Nat. Hist. New York, 7(32): 403.

Number of Recognized Genera: 1

Names

  • English: Bullhead sharks, Horn sharks
  • French: Requins dormeurs
  • Japan: Nekozame-ka
  • Spanish: Dormilones
  • South Africa: Husha k’o, Bulkophaaie
  • Russia: Bych’i akuli
  • Mozambique: Tubaröes dorminhocos
  • Other Names: Port Jackson bull-head sharks, Port Jackson sharks, Akula rogataia, Rogatye akuly

Diagnostic Features Of Bullhead Sharks

Bullhead sharks are found in warm-temperate tropical and continental waters of the western Indian Ocean and the western and eastern Pacific Ocean and are not found in the island waters of the Atlantic. Bullhead sharks are warm temperate to tropical ground sharks in waters below 21 degrees Celsius and are restricted to continental and island shelves on the top slopes. Some species prefer at least crevices and caves where they spend the day. They occur in tides up to 275 m, but most occur in waters shallower than 100 m. Known bullhead sharks can be sluggish and are rare or rare at night when active sharks swim or crawl on rocky or seaweed-covered sandy bottoms.

Sharks are egg-shaped and produce eggs with unique large spiral egg shells. Two types lay eggs at certain Nistplätze. A species migrates in coastal waters, whereby the adult animals return to their breeding ground after a yearlong migration. The eggs take about five months to hatch, and the young hatch in large size (up to 14 cm).

Bullhead sharks feed mainly on benthic invertebrates. It is popular to enjoy crabs and sea urchins, while crustaceans, shrimps and other crustaceans, abalone, mussels (Trochidae and Gastropoda), other marine snails, oysters, polychaetes, sipunculid worms and small fish are also eaten. Bullhead sharks are of minimal interest to fisheries and are caught as bycatch in bottom trawls in fisheries that are used or discarded for human consumption as fishmeal.

Several species of bull sharks are kept in aquariums, where they have proven to be hardy and can live for decades. Mating, egg laying, hatching, egg growth and maturation all take place in captivity. Bullhead sharks can be encountered by divers who harass them. Although they are generally considered harmless, they can snap if provoked, pursue their tormentors, or bite.

Most bullhead sharks are caught in low-level fisheries in abundant commercial species such as shrimp. Their presence in tropical coastal waters is under intense fishing pressure and the destruction of habitats such as dynamite and toxic fishing on coral reefs, causing conservation problems in areas where they occur such as the Indo-West Pacific and the tropical East Pacific. Two species of bullhead sharks are in decline due to fishing pressures. One species is currently undergoing ecotourism dives in California.

Literature

  • 1865: Dumeril
  • 1870: Günther
  • 1913: Garman
  • 1941,1966: Fowler
  • 1942: Smith
  • 1972: Taylor
  • 1984: Compagno
  • 1993: Michael
  • 1994: Last and Stevens