The sixgill sharks, Hexanchus, are a genus of deepwater shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Hexanchidae. These sharks are characterized by broad pointed heads, six pairs of gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

 slits, comb-like, yellow lower teeth, and a long tail. It can grow up to 5 m (18 ft) long and weigh over 600 kg (1320 lb). They are abyssal plain
Abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest...

 scavengers with a keen sense of smell and are among the first to arrive at carrion, together with hagfish
Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...

 and rattails. They show a characteristic rolling motion of the head when feeding.

Extant Species

  • Hexanchus griseus  (Bonnaterre
    Pierre Joseph Bonnaterre
    Abbé Pierre Joseph Bonnaterre was a French naturalist who contributed sections on cetaceans, mammals, birds, reptiles, amphibians, and insects to the Tableau encyclopédique et méthodique...

    , 1788)
    (Bluntnose sixgill shark)
  • Hexanchus nakamurai Teng, 1962 (Bigeyed sixgill shark)

External links

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