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article imageScientists studying great white sharks get an awesome surprise

By Megan Hamilton     Aug 12, 2014 in Environment
Floating in the silent waters off of Guadalupe Island, an autonomous vehicle that resembles a torpedo floats in the blue. Then a great white shark, in a cautious arc ascends to investigate this unfamiliar intruder to its world.
Humming quietly and equipped with six cameras, the vehicle captures an astounding scene as the huge shark briefly examines this newfangled oddity, then turns to its left and descends into the darkness, according to The Verge.
There is a brief moment of silence.
Then WHAM! The shark explodes up from the depths and attacks the vehicle, biting it with a resounding series of crackles and crunches. One can only imagine what a seal hears as its bones break when one of these sharks attacks. The footage is impressive and the scientists involved are excited.
On their boat a few hundred feet above, scientists Amy Kukulya and Roger Stokey, along with their crew, are amazed. The footage is above and beyond what scientists from the Woods Hole Oceanographic Institute (WHOI) had hoped for. The organization is dedicated to developing tools for and in conjunction with fellow scientists. Kukulya is a senior engineering technician and she's interested in underwater systems and especially in autonomous vehicles, per The Verge.
In November, 2013, the institute worked in conjunction with the Discovery Channel in preparation for Shark Week, and the scientists and crew members know they now have footage that's unlike anything that's been seen before.
Kukulya and her fellow engineers had prepped for this expedition for years, researching and finding ways to improve autonomous vehicles so that they could be taught to follow sharks. Kukulya started out by training them to follow boats, then to track a diver riding a scooter zipping around the ocean depths.
"The idea is you tag a shark with one of our navigation beacons, these transponders, and the vehicle's basically just interrogating every three seconds, and it's sending back three replies. The first ping gives it a bearing and a range, and then there's a slight delay, and a second ping comes back and gives it depth," she told The Verge. "And so the vehicle's able to triangulate its position, and know exactly in three-dimensional space where the shark is."
Under Water Autonomous Vehicles (UAVs) have long been used for ocean exploration. In fact, UAVs work quite well for detecting things sitting on the seafloor, or for simple moving objects like a boat on the water's surface.
Over time the team has been tweaking the UAV here and there, building up its power and autonomy, per The Verge.
"It becomes a more complicated math problem, essentially," Kukulya said. "So you tag a driver on a scooter and have him randomly drive around, and you see how quickly the vehicle can interrogate the transponder. Then you see how fast it can process that information, and [whether] it can stay close enough, but not too close, to whatever you're following to get the data that you need."
What really makes the SharkCam special is its hardware. The REMUS (Remote Environmental Monitoring Units) SharkCam, at about 100 pounds, has a range of 45 nautical miles. At nearly seven feet long, it has six GoPros wrapped in sturdy housing that lets it go down to 150 meters. Equipped with navigational tools, it has an onboard computer that helps it track a great white, The Verge reports.
The crystal-clear waters off of the coast of Mexico offered 100 feet of visibility, allowing the team to see all the way down to the edge of darkness. They'd be able to watch sharks hunting, mating, and observe sharks in the wild in ways that were previously not possible.
The team hopes to use this technology to study whales, sharks, sea turtles and scores of other marine creatures.
The modern great white shark (Carcharodon carcharias) has been swimming the oceans for 11 million years, according to ReefQuest Centre for Shark Research.
White sharks grow to become the largest predatory fish in the ocean, attaining lengths of more than 6.1 meters long and they can weigh as much as 2,268 kilograms, or 4,409 pounds. There have also been reports of sharks as large as 7.62 meters, and it's thought that the name "white shark" came from the fish's all-white body, according to Marinebio.org.
With it's crescent-shaped tail, the great white is a powerful swimmer and it steers itself in a rather stiff-bodied fashion, similar to how tuna swim. Shaped like a torpedo, these majestic fish are related to mako and salmon sharks.
Great whites have a a wide geographic distribution and can be found in cold temperate and tropical waters, Marinebio reports. It was once thought that these sharks primarily inhabited coastal areas, but satellite tracking studies have shown that they migrate long distances--sometimes covering entire ocean basins.
Great whites can be found hunting elephant seal haul-outs along the central California coast from October through March. From May through September, they can be found prowling the western cape of South Africa, where they favor cape fur seal. They have also been found from Newfoundland to Florida, and from the Aleutian Islands to southern Mexico, Marinebio reports. Throughout their range, great whites aren't very common and are becoming increasingly rare.
Research on interactions between great whites and species of seals and sea lions shows that these sharks likely hunt their prey visually. Cruising around near rocky bottoms, the dark coloring on the backs of white sharks make them difficult to see, and they watch for unsuspecting seals on the surface above. Once a seal is sighted, the great white accelerates rapidly to the surface and rams into it, stunning the animal and taking a large bite at the same time. Then the shark returns to feed on the carcass.
Hunting like this is risky business and great whites often bear heavy-duty battle scars from the teeth and claws of elephant seals and sea lions.
White sharks have other problems as well. They are listed as vulnerable to extinction by the IUCN Red List of Threatened Species. While this shark gets a lot of media attention, relatively little is known about its biology, per Marinebio. Great whites have been reported most frequently from South Africa, Australia, California, and the northeastern US, but they appear to be less common than other widely distributed sharks. Threats to this shark include targeted commercial and sports fisheries for jaws, fins, game records, and for aquarium display, as well as media-fueled campaigns to kill great white sharks after someone is bitten. Destruction of inshore habitats that are used for giving birth and as nursery grounds for juvenile sharks is also a problem.
Hopefully the research being conducted by the scientists from WHOI will help to increase our knowledge of these magnificent creatures so that they may prowl the oceans for generations to come.
More about woods hole oceanographic institute, Great white shark, Discovery Channel, the verge
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