Sharks Use Earth's Magnetic Field To Navigate the Seas (sciencemag.org) 16
A new study suggests some sharks can read Earth's field like a map and use it to navigate the open seas. ScienceMag: The result adds sharks to the long list of animals -- including birds, sea turtles, and lobsters -- that navigate with a mysterious magnetic sense. "It's great that they've finally done this magnetic field study on sharks," says Michael Winklhofer, a biophysicist at the Carl von Ossietzky University of Oldenburg in Germany, who was not involved in the study. In 2005, scientists reported that a great white shark swam from South Africa to Australia and back again in nearly a straight line -- a feat that led some scientists to propose the animals relied on a magnetic sense to steer themselves. And since at least the 1970s, researchers have suspected that the elasmobranchsâ"a group of fish containing sharks, rays, skates, and sawfish -- can detect magnetic fields. But no one had shown that sharks use the fields to locate themselves or navigate, partly because the animals aren't so easy to work with, Winklhofer says. "It's one thing if you have a small lobster, or a baby sea turtle, but when you work with sharks, you have to upscale everything."
Bryan Keller, an ecologist at Florida State University, and his colleagues decided to do just that. The researchers lined a bedroom-size cage with copper wire and placed a small swimming pool in the center of the cage. By running an electrical current through the wiring, they could generate a custom magnetic field in the center of the pool. The team then collected 20 juvenile bonnethead sharks -- a species known to migrate hundreds of kilometers -- from a shoal off the Florida coast. They placed the sharks into the pool, one at a time, and let them swim freely under three different magnetic fields, applied in random succession. One field mimicked Earth's natural field at the spot where the sharks were collected, whereas the others mimicked the fields at locations 600 kilometers north and 600 kilometers south of their homes. When the applied field was the same as at the collection site, the researchers found that the animals swam in random directions. But when subjected to the southern magnetic field, the sharks persistently changed their headings to swim north into the pool's wall, toward home, the researchers report today in Current Biology
Bryan Keller, an ecologist at Florida State University, and his colleagues decided to do just that. The researchers lined a bedroom-size cage with copper wire and placed a small swimming pool in the center of the cage. By running an electrical current through the wiring, they could generate a custom magnetic field in the center of the pool. The team then collected 20 juvenile bonnethead sharks -- a species known to migrate hundreds of kilometers -- from a shoal off the Florida coast. They placed the sharks into the pool, one at a time, and let them swim freely under three different magnetic fields, applied in random succession. One field mimicked Earth's natural field at the spot where the sharks were collected, whereas the others mimicked the fields at locations 600 kilometers north and 600 kilometers south of their homes. When the applied field was the same as at the collection site, the researchers found that the animals swam in random directions. But when subjected to the southern magnetic field, the sharks persistently changed their headings to swim north into the pool's wall, toward home, the researchers report today in Current Biology
But will putting lasers on them mess up the sense? (Score:5, Funny)
But will putting lasers on them mess up the sense?
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Com on... nobody needs sharks, but if you have sharks they obviously need frikken lasers strapped to their heads.
There is minimal interaction between magnetic fields and photons in either vacuum or virtually any medium, so lasers are extremely unlikely to affect a magnetic sense.
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>nothing really new here.
I beg to differ - moving from assumption to knowledge is something very significant. It's just not surprising or disruptive.
A dismissive attitude towards such studies, along with those that try to replicate previous studies, is the primary reason the quality of so much science has declined. Questioning assumptions and independent replication are the meat and potatoes of science - the flashy new exciting discoveries are usually eventually proven wrong, it's the "boring" stuff th
Earth's magnetic field reverses? (Score:2)
How do sharks survive through reversals of the earth's magnetic field?
I think an sharknado happens at that time! (Score:2)
I think an sharknado happens at that time!
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The same way they survive moving into new territory I'd imagine.
Magnetic navigation helps them find "home", if the fields change, they probably just remember the new feeling of "home" - it's not like fields change really quickly on biological timescales - at the fastest you're talking tree-growing timescales. You could still find home even with fast-growing trees all over the neighborhood changing the look. And a full pole reversal actually takes around 7000 years, though the changes are faster near the e
Some real news!!! (Score:2)
That's pretty interesting actually. I mean, literally swimming across the pacific in a straight line. I wonder how the sharks are impacted whenever their is a pole reversal, which has been known to happen.
Clearly the shark has survived previous pole reversals, though many species don't. Many of the pole reversals seem to coincide with several of the mass die offs that have occurred.
They should of posted the story about the Australian man that got bit by a shark, lost his leg AND had to fight a court battle
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They should of posted the story about the Australian man that got bit by a shark, lost his leg AND had to fight a court battle over getting to keep the shark tooth that was lodged into his surf board. They did eventually let him keep it but apparently it's a crime to have any part of a protected animal, and the particular shark was protected, even though the tooth was left behind.
I suppose you could argue it was a gift from the shark. A souvenir, if you will. "Great to have you, come again any time!"
How cute, me too (Score:2)
I use a special gizmo that uses the earth's magnetic field to make a needle point to North.
So I always get lost more northerly.
Compasses are stupid (Score:2)
Navigating by the stars is more reliable. Or satellite. Humans are way smarter than sharks. A shark has an IQ of what? 12?
Seriously? (Score:2)
The magnetic field at two points separated by 600km of latitude is minimally different, between 5 and 6 degrees different dip. And you think sharks can detect that difference? Nonsense.
The minimal difference in Earth's magnetic field over long distances is why compasses work over wide regions of the Earth--most if it, in fact, unless you're near a magnetic pole.