The Bluntnose Sixgill shark (Hexanchus griseus), often called the Cow shark, is the largest hexanchoid shark, growing to probably 18-26 feet in length. It is found in tropical and temperate waters worldwide and its diet is widely varied by region.
Family: Hexanchidae – Cow Sharks
Genus: Hexanchus
Species: griseus
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Cow and Frilled Sharks
Common Name– Cow Sharks
Genus– Hexanchus
Species– griseus
Status: IUCN Red List NEAR THREATENED
Average Size and Length: The Bluntnose Sixgill shark can grow to probably between 18-26 feet long. Adult males generally average between 10 and 11 feet, while adult females average between 11 and 14 feet.
Current Rare Mythical Sightings: The Bluntnose Sixgill shark resembles many of the fossil sharks from the Triassic period. A greater number of Hexanchus relatives occur in the fossil record than are alive today.
An adult Bluntnose Sixgill shark was recently seen at a depth of 854.7 feet in the Philippines. On December 2, 2017, the ROV camera of Paul Allen’s research vessel RV Petrel captured video footage of the shark lurking around a WWII shipwreck in Ormoc Bay. This was the first time the species was photographed in Philippine waters. In 2018, a Sixgill shark was filmed near the Saint Peter and Saint Paul Archipelago, midway between Brazil and Africa, at a depth of around 400 feet. (Catoto, Roel. “Rarely seen shark sighted in Ormoc Bay | MindaNews”. www.mindanews.com. Retrieved 2017-12-22).
Teeth and Jaw: It has a ventral mouth. There are 6 rows of saw-like teeth on its lower jaw and smaller teeth on its upper jaw.
Head: The snout is blunt and wide, and its eyes are small. Its pupils are black, and its eye color is a fluorescent blue-green.
Tail: The Bluntnose Sixgill shark has a very long tail.
Demographic, Distribution, Habitat, Environment and Range: The Bluntnise Sixgill shark has global distribution in tropical and temperate waters. It is found in a latitudinal range between 65°N and 48°S in the Atlantic, Indian, and Pacific oceans. It has been seen off the coasts of North and South America from North Carolina to Argentina and Alaska to Chile. In the eastern Atlantic, it has been caught from Iceland to Namibia, in the Indo-Pacific it has been caught from Madagascar north to Japan and east to Hawaii, and in the Mediterranean, it has been caught in Greece. It typically swims near the ocean floor or in the water column over the continental shelf in poorly lit waters. It is usually found 1,640–3,610 feet from the surface, inhabiting the outer continental shelf, but its depth range can extend from 0, to at least 6,152-8,202 feet. Juveniles will swim near the shoreline, in colder temperatures, in search of food, sometimes in water as shallow as 39 feet, but adults typically stay at depths greater than 330 feet, but sometimes in shallow water over submarine canyons. It can be seen near the ocean’s surface only at night.
Diet: It has a wide variety of benthic and pelagic prey, including fish, rays, chimaeras, squid, crabs, shrimps, seals, and other sharks.
In 2013, during filming for the Shark Week episode “Alien Sharks”, Bluntnose Sixgill sharks were found to be territorial as one was filmed laying claim to the carcass of a sperm whale calf that was being used to lure deep-sea shark species within range of submarine cameras. The shark was recognized as being the same individual by the scars on its back and sides, and the bites it removed from the carcass allowed other animals, such as hagfish, to feed and further break down the dead whale (Alien Sharks, 2013).
Bluntnose Sixgill sharks may not have an opportunity to eat for an entire year. Therefore, when they find and scavenge large carcasses on the sea floor, they will gorge.
Ram-Suction Index: They rip and tear chunks of flesh off of prey by trashing their heads and bodies from side to side.
Aesthetic Identification: The Bluntnose Sixgill shark has a large, heavy and powerful body, with soft fins. Skin color ranges from tan, through brown, to black. It has a light-colored lateral line down the sides and on the fins’ edges, and darker colored spots on the sides. Newborns have a counter-shaded lighter underside. They have one dorsal fin located near the caudal fin. The pectoral fins are broad, with rounded edges. It has 6 gill slits.
Biology and Reproduction: The Bluntnose Sixgill shark is ovoviviparous with embryos receiving nourishment from a yolk sac while remaining inside the mother. Litters are large and typically have 22-108 pups measuring 24–30 inches at birth. Gestation period is unknown and unconfirmed at this time. Females reach sexual maturity at 15 feet in length and males 10.3 in length. They are thought to be long-lived.
Researchers are possibly studying the courtship habits of the Bluntnose Sixgill shark.
Behavioral Traits, Sensing and Intelligence: Bluntnose Sixgill sharks can occur alone or in groups. They are often sensitive to light. Adults are passive, and younger sharks tend to be more aggressive.
Young and adults may be segregated.
Bluntnose Sixgill sharks have a slow metabolism and they conserve energy any way they can. They are extremely slow-moving typically.
Bluntnose Sixgill sharks have an extremely acute sense of smell.
Speed: Although sluggish in nature, the Bluntnose Sixgill shark is capable of attaining high speeds for chasing and catching its prey using its powerful tail.
Bluntnose Sixgill Shark Future and Conservation: Its longevity and popularity as a sport fish makes it vulnerable to exploitation and unable to sustain targeted fishing for very long. Although it is usually caught as bycatch, it is also caught for food and sport.
Bluntnose Sixgill Shark Recorded Attacks on Humans: Harmless to humans unless provoked. Smaller sharks can be more aggressive if caught. Larger sharks are reported docile by divers.