is mainly a deep water shark, rarely found at depths of less than 100 m. The species seems to usually stay close to the bottom, near rocky reefs or soft sediments. The deepest one has been found was about 2500 m.
There exist size differences between male and female sharks. Females tend to be slightly larger than males, averaging around 4.3 m in length while males tend to stay near 3.4 m. There is little or no color difference between the sexes; however, the seasonal scars appearing on the fins of females, which are believed to be a result of mating, are commonly used for sex identification. Sex can be easily determined by the presence of elongate claspers on the pelvic fins of male sharks. The bluntnose sixgilled shark is classified under the genus Hexanchus with only one other species, Hexanchus nakamurai, or the bigeyed sixgill shark. Both sharks are similar in all aspects aside from their unmistakable size difference. While H. nakamurai reaches only about 2.3 m in length, reaches lengths of 4.8 m. (Parker and Parker, 2002)
Little is yet known about the life cycle and fetal development of (Ebert, 2002).
Very little is known about these sharks in terms of their social behavior and thus little is known about their mating systems. There are a few theories, however, attempting to explain how (MacQuity and King, 2000)mates. Researchers believe that the morphology of the teeth of play an important role in mating. The male has a more erect primary cusp than do the females. The male is believed to nip the female's gills with this cusp in order to catch her attention and entice her into mating. Evidence supporting this idea of courtship is evident by the seasonal scars that appear on females every year presumably from being nipped by males. Bluntnose sixgill sharks are believed to be primarily solitary animals and there is no information indicating whether they prefer one or many mates.
There is no information available pertaining to parental care for (Martin, 2000). However, as with other sharks, it can be assumed that no parental care is given to the young, which can number up to 108.
crabs and shrimp), agnathans (Hagfish and sea lampreys), chondrichthyans (ratfish) and teleosts (dolphinfish and lingcod). A subspecies of living in Cuban waters is also a skilled scavenger that feeds on carcasses of mammals. (Parker and Parker, 2002)is a skilled predator and is solely carnivorous, feeding on such animals as fishes, rays, and other sharks. Although they have been reported as being sluggish in nature, their body structure enables them to reach remarkable speeds for chasing and effectively capturing prey. Aside from feeding on molluscs and marine mammals, they eat crustaceans (
This species is a large, deep-water predator, but we have little information on its ecological effects. There is some evidence that white sharks' population off the coast of South Africa. Researchers there believe that will eventually outcompete Carcharodon carcharias in that area. is not known to participate in any symbiotic relationships. (Martin, 2000; Musick and McMillan, 2002)has an important impact on the
This species is killed for food, harvested with line gear, gill nets, and other equipment. It is also caught by game fishermen.
Since they are large and widespread animals, these sharkes they may have a significant role in deep-water fisheries, but we have no information on this. (Bester, 2001; MacQuity and King, 2000; Martin, 2000; McFarlane , et al., 2002)
Despite their size, these sharks are not considered much of a direct threat to humans. They are described as shy, nonagressive animals that pose no threat to humans unless physically provoked. Also, their preference for deep water and darkness makes human encounters with this species relatively rare.
Some medical professionals consider the liver ofto be toxic, as its ingestion has been known to cause painful sickness for up to 10 days. The skin of has also been known to cause such sickness.
Fishermen are killing (Bester, 2001)for sport and for food (as they are being more frequently spotted in fishing areas) faster than ever before. Because of their low reproductive rate, sixgill sharks can easily be over-harvested. There are new regulations being enacted prohibiting the recreational killing of these sharks. The IUCN rates this species as "Lower Risk/Near Threatened", and notes that the lack of population data means that this species could be in more trouble than we know.
are mainly deepwater sharks with shy demeanors. Opportunities to study live specimens are few and far between. Bluntnose sixgill sharks kept in captivity suffer from stress due to their light-sensitive eyes and their large size.
David Armitage (editor), Animal Diversity Web, George Hammond (editor), Animal Diversity Web.
Jessica Bauml (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
uses sound to communicate
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
active during the night
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
Shark Foundation. "Hexanchus griseus" (On-line ). Accessed 3/17/03 at http://www.shark.ch/cgi-bin/Sharks/spec_conv.pl?E+Hexanchus.griseus.
IUCN. "IUCN Red List of Threatened Species: Hexanchus griseus" (On-line ). Accessed 3/19/03 at http://www.redlist.org/search/details.php?species=10030.
Bester, C. 2001. "Bluntnose Sixgill Shark" (On-line). Icthyology at the Florida Museum of Natural History. Accessed December 07, 2004 at http://www.flmnh.ufl.edu/fish/Gallery/Descript/BSixgill/Bsixgill.html.
Ebert, D. 2002. Some observations on the reproductive biology of the Sixgill Shark Hexanchus griseus . South African Journal of Marine Science, 24: 359-363.
MacQuity, M., D. King. 2000. SHARKS. New York: DK Publishing, Inc.
Martin, R. 2000. "Biology of the Bluntnose Sixgill" (On-line). Accessed July 28, 2004 at http://elasmo-research.org/research/sixgill.htm.
McFarlane , G., J. King, M. Saunders . 2002. Preliminary study on the use of neural arches in the age determination of bluntnose sixgill sharks. Fish Bulletin, 4: 861-864.
Musick, J. A., B. McMillan. 2002. The Shark Chronicles. New York: Henry Holt and Company, Inc.
Nevell, L. "British Marine Life Study Society: Six-gilled Shark" (On-line ). Accessed 3/17/03 at http://ourworld.compuserve.com/homepages/BMLSS/six-gill.htm.
Parker, S., J. Parker. 2002. The Encyclopedia of Sharks. Ontario: Firefly Books LTD.