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February 3, 2016

Shark v Drone — Video of the Ultimate Battle

Screen Shot 2016-01-22 at 9.58.29 PM

From The Guardian:

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Great white shark's predatory behavior captured by underwater drone video

A team of marine biologists discovered that great white sharks ambush prey from the ocean's dark depths, as they attacked drones recording their movements

Great white sharks appear to use darkness and depth to ambush prey, marine biologists have learned, thanks to unprecedented footage by an undersea drone that was attacked nine times by four sharks.

In the 13 hours of footage, the sharks cruise low above the sand, swim up to the robotic vehicle and inspect it from all sides, bump it curiously, and burst out of the blue to seize the drone in their jaws.

In research published last December in the Journal of Fish Biology, the scientists described the first great white predatory behavior filmed from under the surface.

"Most of what we know from white sharks is from electronic tagging, or from what we see at the surface," Greg Skomal, a biologist and lead author told the Guardian. "But when these sharks disappear, what they're actually doing at depth, where they spend their time — we don't have a sense of that."

He said automated unmanned vehicles (AUVs) like his team's let humans observe marine life in comprehensive detail, rather than what scientists can see in the fleeting shark breaches, or their encounters at the surface or through electronic tracking.

From the waters off Guadalupe, an island off Mexico where Pacific white sharks congregate, the scientists observed 10 different individuals, including the 20-foot female named Deep Blue and a local shark nicknamed Bubba.

Skomal said that the behavior captured by the drone cameras supports the idea that white sharks dive down as far as 200 meters in order to use light to their advantage.

"If the shark hangs down at a great depth, in the darkness, then its prey swims above it silhouetted and the shark reduces its own likelihood of detection," Skomal said.

"The remarkable new observations indicate that [my colleagues'] hypothesis is correct, and the sharks ambush from the darkness."

Most surprising to the researchers, Skomal said, was that "the hunter would become the hunted — the AUV was viewed by the shark as potential prey and aggressively attacked."

Some sharks did not bite but rather bumped the drone, nudging the vehicle with their snout in what the researchers call an "agonistic" behavior — an aggressive or even defensive thump, but not anything like a committed attack.

At other times the sharks simply approached the drone to look at it, before moving on along their way.

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Video below.

February 3, 2016 at 08:01 AM | Permalink | Comments (2)

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