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. 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 and
Malta. Fossilized remains of this species from the
Middle Miocene have also been discovered in the
Duho Formation of
South Korea. It typically swims near the ocean floor or in the
water column over the
continental shelf in poorly lit waters. Juveniles will swim near the shoreline in search of food, sometimes in water as shallow as , but adults typically stay at depths greater than . It can be seen near the ocean's surface only at night. 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 . In 2019, the remains of a pregnant bluntnose sixgill shark were found on a
Vancouver Island beach, north of
Victoria,
British Columbia. On 18 October 2019, a large bluntnose sixgill shark measuring over and weighing 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. Research has found that it takes more time for the sixgills to have to swim back down to their natural habitat of the bathypelagic rather than to swim up during the night to find food in the more populated zones. As such, it can be inferred that they have some sort of adaptation that aids buoyancy to ensure that these sharks are able to float more easily. An example of this DVM occurrence was found off the coast of
Oahu, Hawaii, whereby 4 sixgills' behaviors were studied. Between midnight and 3 AM, the 4 sharks swam up to a minimum depth of whereas at about noon, they reached their maximum depth of between . 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. Researchers were able to rule out predator and competitor avoidance as potential reasons for the vertical movement patterns because they found pairs of sharks with synchronized movements, indicating that the sharks were responding to the same stimuli. The sharks demonstrated distinct and consistent patterns of vertical migration despite size, sex, and spatial scales, showing that foraging behavior can most likely be seen as the reason for the diel vertical patterns of sixgill sharks. Lastly, the bluntnose sixgill shark has consistent seasonal movements. They move north during the winter and spring and south during the summer and fall. In this study as well, researchers were able to determine that these movement patterns can be attributed to the seasonal movements of prey over other reasons. == Feeding behavior ==