Sea Turtles

Though all seven species of sea turtles are threatened or endangered, they are still found in every ocean except the Arctic. Believed to use the Earth's magnetic field to navigate, sea turtles have an extraordinary sense of time and location, and most species return to nest at the exact place where they were born. Certain species even swim ashore together in a single, mass arrival. After a few months, hundreds of hatchlings dig their way out of the nests and seek the ocean. How do they find it? More...

Their eggs look like table tennis balls. And on a plate in a restaurant even like battered tennis balls.
Barnacle.

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J'ai perdu mes amis en Afrique durant la dernière semaine de 2017

How Do Sea Turtles Find the Exact Beach Where They Were Born?
The marine reptiles use Earth's magnetic field as a guide back home, new study says.
By Carrie Arnold, National Geographic

PUBLISHED January 16, 2015

After hatching on beaches around the world, these huge marine reptiles undertake multiyear, epic migrations at sea. Then, the turtles return to the exact spot where they were born to mate and lay their own eggs. ... Now a new study has the answer: The turtles also rely on Earth's magnetic field to find their way home.


For loggerhead sea turtles, home is where your (magnetic) heart is.

After hatching on beaches around the world, these huge marine reptiles undertake multiyear, epic migrations at sea. Then, the turtles return to the exact spot where they were born to mate and lay their own eggs.

Scientists have long known that the turtles, like many animals, navigate at sea by sensing the invisible lines of the magnetic field, similar to how sailors use latitude and longitude. But they didn't know how the turtles were able to return to the very spot where they were born. (See "Migrating Monarch Butterflies Use Magnetic Compass to Cut Through Clouds.")

For loggerhead sea turtles, home is where your (magnetic) heart is.

After hatching on beaches around the world, these huge marine reptiles undertake multiyear, epic migrations at sea. Then, the turtles return to the exact spot where they were born to mate and lay their own eggs.

Scientists have long known that the turtles, like many animals, navigate at sea by sensing the invisible lines of the magnetic field, similar to how sailors use latitude and longitude. But they didn't know how the turtles were able to return to the very spot where they were born. (See "Migrating Monarch Butterflies Use Magnetic Compass to Cut Through Clouds.")

Now a new study has the answer: The turtles also rely on Earth's magnetic field to find their way home. That's because each part of the coastline has its own magnetic signature, which the animals remember and later use as an internal compass.

It's not an easy commute, though—the magnetic field changes slowly, and loggerheads have to shift their nesting sites in response, according to the study, published January 15 in Current Biology.

"It's pretty fascinating how these creatures can find their way through this vast expanse of nothing," said study co-author J. Roger Brothers, a biology graduate student at the University of North Carolina, Chapel Hill.


https://news.nationalgeographic.com/news/2015/01/150115-loggerheads-sea-turtles-navigation-magnetic-field-science/