Wednesday, January 5, 2011

How turtles can conquer Atlantic by swimming thousands of miles in a perfectly straight line


Are we there yet? Leatherback sea turtles travel thousands of miles for anything up to 150 days to reach feeding and breading grounds

They are famed for their epic voyages across the world's roughest oceans.
But until now, nobody quite appreciated just how good leatherback turtles were at navigation.

In a new study, British scientists have discovered that the gigantic females can swim for thousands of miles in a perfectly straight line.

Following a course that would be the envy of a state-of-the-art cruise liner, the turtles make the transatlantic journey from Central Africa to South America using the shortest possible route.

Inbuilt sat-nav: Scientists from Exeter University have now discovered that these amazing creatures are able to make their long journeys traveling the shortest possible route - often swimming in a perfectly straight line

Exactly how turtles can swim in a straight line remains a mystery to biologists.
However, they are thought to use a combination of vision - relying on the position of the stars and sun - and a sense of the Earth's magnetic field, to steer their way.

Fancy a dip? Leatherbacks spend almost their entire lives in the water. The only time they leave their watery sanctuary is when they are nesting or when hatchlings, like this little fella, emerge from their nests

The findings come from a study led by the Centre for Ecology and Conservation at Exeter University.

Over five years, the researchers tagged 25 females with satellite tracking devices strapped or drilled to their shells as they left their hatching grounds in Africa to seek food across the Atlantic.

They discovered three migratory routes - including one 4,699 mile journey straight across the Atlantic from Gabon to the coastal waters off southern Brazil and Uruguay that took 150 days.

Dr Matthew Witt, who published the findings in the journal Proceedings of the Royal Society B, said: 'Despite extensive research carried out on leatherbacks, no-one has really been sure about the journeys they take in the South Atlantic until now.

'What we’ve shown is that there are three clear migration routes as they head back to feeding grounds after breeding in Gabon, although the numbers adopting each strategy varied each year.

'We don’t know what influences that choice yet, but we do know these are truly remarkable journeys – with one female tracked for thousands of miles travelling in a straight line right across the Atlantic.'

A map of the three routes taken by migrating turtles. Group 2, made up of leatherback turtles, travelled in a straight line

source: dailymail

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