He demonstrated that effect in a seaside pen in the Bahamas. His field assistant, T. J. Ostendorf, captured a small lemon shark and slowly rotated it onto its back, underwater. That put the shark into a sleep-like state. Then Stroud took a magnet and spun it as he moved it toward the shark. The shark immediately bent away from the magnet — “like it’s another magnet,” Stroud said...It appears that the magnet needs to be spinning or rotating. So it's not enough to keep one in your pocket while swimming.
Sharks possess electrical sensors, called the ampullae of Lorenzini, that look like tiny freckles on their snouts. Biologists believe sharks use these sensors to detect the heartbeats of their prey and to navigate using the Earth’s magnetic field. Stroud suspects the spinning magnet overwhelms those electrical sensors.
“It’s probably something like a bright flashlight across your eyes,” he said. “It’s just temporarily blinding, and you’re startled. And it’s not pleasant.”..
Many shark species are being overfished, and some are endangered. One reason is that fishermen trying to catch other fish often catch sharks by accident. Stroud wondered – what if he could produce fishhooks that catch fish like tuna and halibut as usual, but that sharks avoid?
More at Public Radio International.
ليست هناك تعليقات:
إرسال تعليق