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Bluntnose sixgill shark

2/16/2016

 
Picture© Andy Murch
We bring you…. drumroll, please… the bluntnose sixgill shark (Hexanchus griseus)! 
Other common names include, “cow shark” and “mud shark," and they’re actually a pretty common, large deep water shark (up to 5.4 m /18 ft large; females tend to be bigger than males).


They are one of the few members in the Hexanchidae family, and this shark has an unusual number of gill slits (six). Their coloration varies from brown, gray or even black, with small, bright green eyes that have a large, black pupil. 

They are a pretty stocky animal, with a rounded, blunt snout. They have one dorsal fin and it’s like all the way back, by the tail. This shows that they’re slow, sluggish swimmers but can be pretty persistent when chasing after their food (crustaceans, fish, rays, dead mammals and cephalopods). 

Sixgill sharks are pretty cosmopolitan, often found at depths of about 90 m (300 ft), but sometimes found in the shallows and can come in contact with divers; but no worries, they aren’t dangerous. In fact, they tend to stick to themselves… which is why we don’t really know much about their reproductive tendencies, or much at all. We do know they’re viviparous with yolk-sac, and can have anywhere from 22 to 108 pups born (WOAH).

There’s probably a really high mortality rate and not many survive to maturity (apparently they can live up to 80 years).  According to the IUCN, they are assessed as Near Threatened (NT). However, since we know so little about them… it sadly could be worse. 

ever gone diving with these sharks before?

glossary

  • Cephalopods: The most intelligent, mobile, and largest of all molluscs. These include: squid, octopuses, cuttlefish, the chambered nautilus, and their relatives.
  • Cosmopolitan: Worldwide distribution.
  • Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
  • Dorsal fin: Fin located on the back.
  • IUCN: International Union for Conservation of Nature.
  • Pelvic fins: Fins located behind the gills on either side.
  • Pups: Baby sharks.
  • Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.

say hello!

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    Author

    TFUI Founder Melissa C. Marquez is author of all animal bios and "Behind the Fins" segments.
    ​
    A proud #LatinainSTEM, Marquez is a marine biologist who focuses on shark habitat use and movements; she is also a science communicator (follow her on Twitter) who focuses on diverse Chondrichthyan education and who focuses on the media coverage of sharks.
    You can learn more about her on her website.

    SEE MELISSA'S TEDx TALK HERE:

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  • About TFUI
    • TFUI Origins >
      • About TFUI Founder Melissa
      • TFUI Officers
    • Take a Bite
    • Get Involved
    • FAQ
  • Bite Blog
  • Education
    • The Sharks >
      • Shark Anatomy
    • The Skates & Rays
    • The Chimaeras
    • Why Environments Matter
    • The Threats
    • Open Access >
      • Behind the Fins: Interview series
      • Bite into Research
      • Shark Bites: Book Recommendations
      • Sustainable Seafood Apps
  • Fins United
    • Shark Party Ideas
    • Little Fins Nursery
    • Big Fins Reef
  • Contact