Hexanchus

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title: "Hexanchus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["hexanchus", "albian-genus-first-appearances", "extant-early-cretaceous-first-appearances", "shark-genera", "taxa-named-by-constantine-samuel-rafinesque"] description: "Genus of sharks" topic_path: "general/hexanchus" source: "https://en.wikipedia.org/wiki/Hexanchus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of sharks ::

| fossil_range = | image = Hexanchus griseus (Bluntnose sixgill shark).gif | image_caption = Bluntnose sixgill shark (Hexanchus griseus) | taxon = Hexanchus | authority = Rafinesque, 1810 | type_species = Squalus griseus | type_species_authority = Bonnaterre, 1788 | subdivision_ranks = Species | subdivision = See text

The sixgill sharks are a genus, Hexanchus, of deepwater sharks in the family Hexanchidae. These sharks are characterized by a broad, pointed head, six pairs of gill slits, comb-like, yellow lower teeth, and a long tail. The largest species can grow up to 8 m long and weigh over 600 kg (1320 lb). They are continental shelf-dwelling and abyssal plain scavengers with a keen sense of smell and are among the first to arrive at carrion, together with hagfish and rattails. They show a characteristic rolling motion of the head when feeding.

They have been found at depths of up to 2500 m. Though only two extant species (the bluntnose sixgill shark and the bigeyed sixgill shark) were originally known, a third, the Atlantic sixgill shark, was found to exist.

Swimming behavior

The bluntnose sixgill shark, Hexanchus griseus, is relatively common to scientists. However, very little information exists about its distribution patterns, migrations and behavior. Data on occurrence and behavior of sixgill sharks inhabiting waters north of Spain (Galicia and Cantabrian Sea, NE Atlantic) were obtained from yearly oceanographic trawl surveys. Data obtained from one electronic pop-up tag (Mini PAT), provided information about depth and temperature preferences over 75 days. Mean depth obtained during that period was 913 m (depth range 727–1247 m), and the mean temperature was 10.3 °C, (range 8.0–10.8 °C). Movements up and down in the water column within a single day ranged from 50 to 385 m. No cyclic diel vertical migration was however observed, the shark having moved smoothly without a defined pattern.

The six-gill sharks have the ability to alter their feeding behaviors due to the situation that they are in. A feeding behavior analysis displayed that the six-gill sharks are able to utilize a bite of food compared to other aquatic vertebrates.

Extant species

• *Hexanchus griseus * (Bonnaterre, 1788) (bluntnose sixgill shark)
• Hexanchus nakamurai Teng, 1962 (bigeyed sixgill shark)
• Hexanchus vitulus Springer & Waller, 1969 (Atlantic sixgill shark)

Extinct species

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/be/Hexanchidae_-_Hexanchus_andersoni.JPG" caption="Fossil teeth of ''Hexanchus andersoni''"] ::

• Hexanchus agassizi Cappetta, 1976
• Hexanchus andersoni Jordan, 1907
• Hexanchus casieri Kozlov, 1999
• Hexanchus collinsonae Ward, 1979
• Hexanchus gracilis Davis, 1887
• Hexanchus hookeri Ward, 1979
• Hexanchus microdon Agassiz, 1843
• Hexanchus tusbairicus Kozlov in Zhelezko & Kozlov, 1999 Records earlier than Albian such as Jurassic species H. arzoensis and H. wiedenrothi are later considered as misidentification, the first moved to Notidanoides and later moved to Crassodontidanus.

References

References

1. (2017-10-02). "Late late Albian (Early Cretaceous) shark teeth from Annopol, Poland". Alcheringa: An Australasian Journal of Palaeontology.
2. (9 May 2017). "Hexanchus griseus".
3. Kindersley, Dorling. (April 2019). "Animal". DK Publishing.
4. "New shark species confirmed: Genetic testing finds a different sixgill shark".
5. "New species of shark discovered through genetic testing".
6. (September 2018). "Insights about depth distribution, occurrence and swimming behavior of ''Hexanchus griseus'' in the Cantabrian Sea (NE Atlantic)". Regional Studies in Marine Science.
7. (March 2020). "[no title cited]". PLOS ONE.
8. (2009). "The oldest hexanchiform shark from the Southern Hemisphere (Neoselachii; Early Cretaceous, Antarctica)". Antarctic Science.
9. Szabó, Márton. (2020-03-01). "A Late Jurassic (Kimmeridgian–early Tithonian) fish fauna of the Eperkés-hegy (Olaszfalu, Bakony Mts., Hungary): the oldest record of Notidanodon Cappetta, 1975 and a short revision of Mesozoic Hexanchidae". Palaeobiodiversity and Palaeoenvironments.

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