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Author Topic: Swiming Efficiency of Aquatic Animals Far exceeds the Propeller  (Read 385 times)

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Sea Turtles Have an Internal ‘GPS’ That Uses Earth’s Magnetic Field

by TreeHugger
January 26, 2015 9:00 am

Written by Michael Graham Richard

Many animals have a talent for finding their way around the globe that any of us who gets lost doing a short trip can’t help but envy. From birds who go back and forth across continents, following the seasons, to the beautiful sea turtles that can find the specific beach where they were born years before to, in turn, lay their eggs. For decades, scientists have wondered how the turtles did it, and it seems like we might finally have an answer thanks to a study conducted at the University of North Carolina at Chapel Hill.

Photo Credit: Les_Williams / Flickr

“Sea turtles migrate across thousands of miles of ocean before returning to nest on the same stretch of coastline where they hatched, but how they do this has mystified scientists for more than fifty years,” said J. Roger Brothers of the University of North Carolina at Chapel Hill. “Our results provide evidence that turtles imprint on the unique magnetic field of their natal beach as hatchlings and then use this information to return as adults.”

To prove that this is the case, the researchers compared 19 years of data on Loggerhead Sea Turtle migration on the Eastern coast of Florida with data on naturally occurring local changes in the Earth’s magnetic field. The scientists found a strong association between the spatial distribution of turtle nests and subtle shifts in the Earth’s magnetic field.

The effect went both ways: When the magnetic fields shifted in such a way that adjacent locations along the beach moved closer, the turtles came back to nest closer together, spreading over a shorter stretch of the coast. When the magnetic signature of certain spots moved apart, the turtles spread out over a longer stretch.

Little is known about how turtles detect the geomagnetic field, but at least we can now show with a fair amount of certainty that they use it.

But why have sea turtles evolved  ::) to go nest where they themselves hatched? It’s all about finding the right conditions; soft sand, the right temperature, few predators and an easily accessible beach.
“The only way a female turtle can be sure that she is nesting in a place favorable for egg development is to nest on the same beach where she hatched,” Brothers said. “The logic of sea turtles seems to be that ‘if it worked for me, it should work for my offspring.’”

Photo Credit: Les_Williams / Flickr

And yes, I’m aware that the Global Positioning System (GPS) that we use to get around doesn’t use magnetic fields, but rather Einstein’s relativity (there’s an explanation here). Using it in the title was just short-hand for a way to navigate to your destination.
Via Journal of Current Biology, Livescience
This post originally appeared on TreeHugger.

Agelbert NOTE: The following comment was even more interesting than the article!  Enjoy.

Beverly S.
3:31PM PST on Jan 27, 2015

Many, if not all animals have an amazing sense of direction. I remember reading that we humans also have a "compass" in our noses, so I did a little research. Interesting!

Some years ago scientists at CALTECH (California Institute of Technology in Pasadena) discovered that humans possess a tiny, shiny crystal of magnetite in the ethmoid bone, located between your eyes, just behind the nose.  :o 

Magnetite is a magnetic mineral also possessed by homing pigeons, migratory salmon, dolphins, honeybees, and bats. Indeed, some bacteria even contain strands of magnetite that function, according to Dr. Charles Walcott of the Cornell Laboratory of Ornithology in Ithaca, New York, "as tiny compass needles, allowing them [the bacteria] to orient themselves in the earth's magnetic field and swim down to their happy home in the mud".

It seems that magnetite helps direction finding in animals and helps migratory species migrate successfully by allowing them to draw upon the earth's magnetic fields. But scientists are not sure how they do this.

In any case, when it comes to humans, according to some experts, magnetite makes the ethmoid bone sensitive to the earth's magnetic field and helps your sense of direction.
Stephen Juan, Ph.D. is an anthropologist at the University of Sydney

Read more: http://www.treehugger.com/natural-sciences/no-place-like-magnetic-home-sea-turtles-gps-earth-magnetic-field.html#ixzz3QBWvIzs4

Agelbert NOTE: Have we lost our PREVIOUS ability to follow earth's magnetic fields through "use it or lose it" SUBTRACTION of genetic material otherwise known as NATURAL SELECTION? Only your Darwinian Evolutionist knows - and they don't want to go there.  Admiting we are LESS "evolved" than we previously were is a NO NO in Darwinian circles. ;D
Hope deferred maketh the heart sick: but when the desire cometh, it is a tree of life. Pr. 13:12


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