[3] The first scientific description of the bluntnose sixgill shark was authored in 1788 by Pierre Joseph Bonnaterre.

Most common sharks today only have five gill slits.In general, sixgills increase in length and weight with maturity.

While juveniles have short and flexible claspers, mature male sixgills have rigid, calcified longer ones.

[9] With a global distribution in tropical and temperate waters, the bluntnose sixgill shark is found in a latitudinal range between 65°N and 48°S in the Atlantic, Indian, and Pacific oceans.

[4] On December 2, 2017, the ROV camera of Paul Allen's research vessel RV Petrel captured video footage an adult bluntnose sixgill shark lurking around a World War II shipwreck in Ormoc Bay, Philippines at a depth of 259 m (850 ft).

[17] In 2019, the remains of a pregnant bluntnose sixgill shark were found on a Vancouver Island beach, north of Victoria, British Columbia.

[18] On 18 October 2019, a large bluntnose sixgill shark measuring over 3 metres (9.8 ft) and weighing 900 kilograms (2,000 lb) was found dead on the beach of Ürkmez in the western province of Izmir, Turkey.

Being in such a deep area of the ocean, these sharks have developed the behavior of undergoing diel vertical migration (DVM) in order to have more access to food.

[20] This shows a daily pattern whereby the sixgills are going up during the nights when it is darker and colder to forage for food up in the shallower depths but as morning comes and light and higher temperatures starts to come in more intently again, the sharks go back down to their original habitat to maintain a lower metabolic rate, ensuring that they will be able to use the nutrients from whatever they ate during the night slowly, reducing the need for them to search for more food throughout the day.

Another study found that the motivating factor for the bluntnose sixgill sharks' DVM behavior was foraging.

[22] Sixgill sharks possess variability in their feeding mechanisms that could have contributed to their evolutionary success and global distribution.

Sixgill sharks also lower their pectoral fins right before they strike in order to stop forward progressions, making it easier for them to forage.

[23] Although sluggish in nature, the bluntnose sixgill shark is capable of attaining high speeds for chasing and catching its prey using its powerful tail.

Because of its broad range, it has a wide variety of prey, including fish, rays, chimaeras, squid, crabs, shrimps, seals, and other (smaller) sharks.

[11] The bluntnose sixgill shark is therefore classified as a generalist species, and is less likely to be affected by scarcity in any one of its food sources.

[24] A study done in 1986, with 28 sixgills, discovered that the most abundant meal they were able to obtain include cartilaginous and bony fishes, followed by marine mammals and several invertebrates.

In 1994, it was found that of 137 samples, the major prey groups were cephalopods, teleost fishes, chondrichthyans and marine mammals.

This is indicated by the greater number of tail beats and the sharks' ability to glide upwards for several minutes.

The positive buoyancy can help the sharks to hunt stealthily by approaching prey from below undetected since the upward gliding permits minimal movement.

Evidence of this hypothesis is that female bluntnose sixgill sharks show up with seasonal scars around their gill slits, which apparently is from breeding with males.

[citation needed] The bluntnose sixgill shark is listed as Near Threatened by the International Union for Conservation of Nature (IUCN) because, despite its extensive range, its longevity and popularity as a sport fish makes it vulnerable to exploitation and unable to sustain targeted fishing for very long.