Scientists Can Tell If Great White Sharks Are Around by Testing DNA in Seawater

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Love the beach but fear sharks? Your risk of dying in a shark attack is infinitesimal—roughly 1 in 3.7 million—but it’s still a risk nonetheless. Scientists say white sharks are becoming more prevalent along California’s coast thanks to federal protections, and on the opposite side of the country, Cape Cod recently saw its first fatal shark attack in more than 80 years.

A new proof-of-concept study, published in Frontiers in Marine Science, could shed new light on what's lurking beneath the surface. Researchers from UC Santa Barbara, the U.S. Geological Survey, and partner universities theorized that environmental DNA (eDNA)—an organism's cast-off bits of genetic material—could show the presence of white sharks in a particular part of the California coast.

White sharks forge distinctive trails by shedding skin and discharging mucus, feces, and other genetic markers in seawater. Researchers created a species-specific test for white shark eDNA, then rode stand-up paddleboards to four sites beyond the line of surf to collect water samples. After analyzing the samples in the lab, they found white shark eDNA in two samples from areas where the fish were known to gather, and no eDNA in the other two samples from sites where sharks hadn't been observed. The results from the preliminary experiment showed that the new test could accurately identify the sharks' eDNA—and that might save a surfer in the future.

"One of the goals of this research is for a lifeguard to be able to walk down to the shore, scoop up some water, shake it, and see if white sharks are around," Kevin Lafferty, lead author of the study, said in a statement.

The use of eDNA has some limitations. Ocean currents can cause eDNA to drift, and that genetic information can degrade quickly in the surrounding environment. “Another challenge is that eDNA might persist in the ocean environment for days, meaning a positive detection might indicate a species that is no longer locally present,” the researchers write in their paper. Still, they say the development is a step in the right direction for better shark monitoring and conservation efforts.

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Poike/iStock via Getty Images Plus

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Do Dogs Get Headaches?

Even without raging benders, dogs might still get headaches.
Even without raging benders, dogs might still get headaches.
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Like babies, dogs can be hard to read in the medical ailment department. Are they listless because they’re tired, or because they’re sick? What’s behind their whining? And can they suffer that most human of debilitating conditions, the headache?

Gizmodo polled several veterinarians and animal behavior specialists to find out, and the answer seems to be a resounding yes.

Although a dog can’t express discomfort in a specific way, particularly if it doesn’t involve limping, animal experts know that canines that have diagnosed brain tumors or encephalitis can also be observed to have a high heart rate, a sign of physical pain. According to Tim Bentley, an associate professor of veterinary neurology and neurosurgery at Purdue Veterinary Medicine, administering painkillers will bring a dog’s heart rate down. If signs of physical distress also decrease, a headache was likely involved.

Unfortunately, not all dogs may offer overt signals they’re feeling some brain pain. According to Adam Boyko, an associate professor of biomedical sciences at the Cornell University College of Veterinary Medicine, dogs instinctively try to mask pain to avoid showing weakness.

Ultimately, dogs have many of the same central neural pathways as humans, which can likely go awry in some of the same ways. But the kind of persistent headaches owing to head colds or hangovers are probably rare in dogs. And while it goes without saying, they definitely don't need any of your Advil.

[h/t Gizmodo]