Orientation and Navigation of Sea Turtles

Long-distance migrations of animals represent one of the great wonders of the natural world.  In the marine environment, migratory movements sometimes reach astonishing extremes: for example, some sea turtles, salmon, sharks, and elephant seals travel distances that exceed the width of oceans before returning to their home areas to reproduce.  How animals find their way during such migrations has remained a central mystery of sensory and behavioral biology.

Sea turtles are among the most impressive navigators in the animal kingdom. As hatchlings, turtles that have never before been in the ocean are able to establish unerring courses towards the open sea and then maintain their headings after swimming beyond sight of land.  Young turtles follow complex migratory pathways that often lead across enormous expanses of seemingly featureless ocean. After completing their years in the open sea, juvenile turtles take up residence in coastal feeding grounds and show great fidelity to their feeding sites, homing back to specific locations after long migrations and experimental displacements.  Similar navigational abilities exist in adult turtles, which migrate considerable distances between specific feeding areas and nesting beaches.

 

Top left: a hatchling green turtle (photo by Ken Lohmann, Univ. North Carolina); Top right: a juvenile green turtle (courtesy of Univ. Central Florida turtle group); Bottom left: Hawaiian green turtles (photo by Ursula Keuper-Bennett and Peter Bennett; Bottom right: hatchling loggerhead turtles (photo by Ken Lohmann)

 

The longest and most spectacular migrations are made by young loggerhead turtles. The journey begins when the hatchlings, each no bigger than a child's hand, dig their way out of their underground nests on the beach and enter the sea. During the vast migration that follows, turtles travel for a period of years along migratory routes that span entire oceans. Young loggerheads in the North Atlantic cover more than 9,000 miles (15,000 kilometers) before returning to the North American coast. Those in the Pacific travel even farther.

How can young sea turtles with no prior migratory experience guide themselves across an entire ocean and back? Considerable progress has been made toward understanding how young loggerheads in the Atlantic Ocean navigate.  To learn about how baby loggerheads guide themselves during their first migration, follow the hatchling links.

Hatchlings embark on an impressive transoceanic migration, but they do not navigate to targets more specific than broad oceanic regions.  In contrast, older turtles acquire an ability to pinpoint specific geographic locations such as feeding areas and nesting beaches.  Recent experiments have demonstrated that sea turtles possess a remarkable ability to exploit positional information in the Earth's magnetic field as a kind of navigational map that can be used to guide movements toward specific goals.   To learn about this research, follow the magnetic map links.

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Much of the research presented in these web pages was made possible by grants from the National Science Foundation.



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Last revised 24 September 2010