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This stress could be enough to temporarily alter this behavior, even though the sharks seemed to tolerate being brought to the surface. "We interpreted that erratic phase as a possible recovery period due to short term physiological stress associated with being captured and brought to the surface." "However, one of the things we noticed is that across all of these sharks there was an initial period of about two days after tagging where the sharks did not show this pattern and seemed to behave a bit more erratically, and then they settled into that distinct vertical migration every day after that," he said. This is a beautifully consistent vertical pattern the sharks undergo every day." "In Exuma Sound this corresponds to coming up to 400-500 meters deep at night and remaining at 900-1200 meters during the day.
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"At dusk they come up the slope sometimes in the water column to shallower depths where water temperature are about 62 degrees Fahrenheit, remaining there overnight, and then at dawn they return to deeper depths where temperatures are 41 degrees Fahrenheit," Grubbs said. Furthermore, the data showed, intriguingly, that these sharks vertically migrate every day and night. This tagging revealed to the researchers that nearly all bluntnose six gills survive being caught and brought to the surface. But all of these were tagged by bringing the sharks to the surface and tagging them alongside the boat or even bringing them onto the deck of ship." Since this time we have tagged more than 20 bluntnose sixgill sharks with archiving satellite tags and another 50 with simple identification tags. "We began this project in 2005 to begin investigating whether deep sea sharks caught and brought to the surface survive if released. "It is often assumed that these deep sea sharks would die if released," he said. Yet as commercial fisheries globally move deeper, deep sea sharks are being increasingly caught, particularly as bycatch." Contrast this with the volumes of scientific information on species like white sharks and tiger sharks. "Yet we know virtually nothing about their biology and ecology. "Approximately half of all living species of sharks on the planet live their entire lives in the deep sea," Grubbs told Newsweek. Tagging them could enable scientists to learn more about their biology and behavior, and protect them from threats. However, researchers know very little about this mysterious species. Females are larger than males."īluntnose sixgills are distributed across tropical and temperate waters around the world usually living at depths of between 650 and 3,300 feet, although they have been spotted up to 5,000 feet below the surface. They are likely primarily carrion feeders, but may also take live prey when the opportunity arises. Females can have over 80 pups in a litter. "They are reported to grow to over 5 meters long and weigh more than a ton. "They have a single dorsal fin that is placed far back on the midline near the tail," Gavin Naylor, one of the scientists on the expedition from the Florida Program for Shark Research at the Florida Museum of Natural History, told Newsweek. They are highly distinctive due to the fact that they have six large conspicuous gill slits, hence the name. In fact, it represents perhaps the oldest living lineage of sharks in the world, the researchers say. The bluntnose ( Hexanchus griseus) is part of an old lineage of sharks that can be traced back 180 million years in the fossil record. She is huge." At one point the shark even tries to nibble on the spear gun attached to Nadir. The sub crew were left in a state of awe by the encounter: "My goodness that is amazing," one of the team comments, while another can be heard saying, "This is a monster. The team, led by Dean Grubbs, from Florida State University, were conducting dives in a submersible called "Nadir" as part of an expedition organized by OceanX to tag one of the sharks in their deep-sea environment.ĭuring one of the dives, the team were fortunate to come up close and personal with a huge female bluntnose-=one of the largest sharks in the world-which one of the researchers in the video can be heard describing as "definitely bigger than the sub is long."
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A team of researchers has captured incredible footage of a close encounter with an ancient species of shark known as the bluntnose sixgill.