NEWS CATEGORIES:

NEWS ARCHIVE >>
SOFTPEDIA REVIEWS >>

Home / News / Science / Nature

Nature

How Can Marine Turtles Always Return to the Same Sex Beach? They detect Earth's electromagnetism	By Stefan Anitei, Science Editor 8th of March 2007, 12:21 GMT Adjust text size:


Scientists have been puzzled for long by the ability of the marine turtles to return their entire life to the same beach to depose their eggs. These egg-laying sites can be often located far from the feeding areas and the individuals (both females and males, as they mate in the same area where the females lay their eggs) swim several hundred kilometers of ocean with no visual landmarks. A new research led by Simon Benhamou of the Center for Functional and Evolutionary Ecology at Montpellier1, France, points out that turtles' exceptional navigational ability relies on detecting the earth's magnetic field, against the deflection induced by the ocean currents. Each 4 years, Indian Ocean green turtles (Chelonia mydas) make a journey of hundreds of kilometers to specific breeding shores, where they will lay 4 to 6 successive clutches. The research team made two experiments. The turtle populations investigated were from Islands of Europa and Mayotte, off the Madagascar coast. Female turtles were captured at the beginning of their egg-laying cycle (thus strongly impelled to return to this area to complete their cycle), tagged with Argos transmitters to satellite track them and released in open sea, several hundred kilometers from the egg-laying site. The researchers wanted to see if turtles' movements were controlled by the currents or if they used them to ease their journey. The marine turtles' navigation system permitted them to keep their direction towards their natal beaches wherever they find themselves, like a compass pointing towards them. They were able to fix any deflection they were subjected to, like boat transportation or ocean currents. The animals could not stand up against ocean drift plotting their track, thus the movements made by the animals were a mix of deliberate actions by the turtles and the slide induced by the oceanic currents, that makes them wander for long periods during adverse ocean weather. One turtle released 250 km away from its egg-laying beach on Europe swam over 3 500 km (2 200 mi) in two months before returning there! In the other investigation, the team checked how much the earth's magnetic field counts on the turtles' navigation system. For the first time was proven what was before just a supposition: marine turtles employ the magnetic field of the earth to navigate. Impairing its detection using a powerful magnet attached on the turtles' heads decreased their navigational sense. They were still able to return to their original egg-laying beach, thus the turtles do not rely only in the geomagnetic field. They probably use olfaction, like some sea birds (petrels and albatrosses) or homing pigeons do, but this is just a supposition by now.

TAGS:

turtle | magnetic | egg

Rating:

Good (3.5/5)

6 vote(s) so far

Read by 1,321 user(s) | Add comment | Link to this article

Subscribe to news |

Print article |

Send to friend

© Copyright 2001-2008 Softpedia
Contact:

SEARCH THE NEWS ARCHIVE :

Today's News | Yesterday's News | News Archive

MORE RELATED ARTICLES:

Marine Monsters from Dinosaur Era Discovered in Svalbard Archipelago

Why Some Bacteria Are Magnetic?

Crocodile Sex Is Not Hotter with Global Warming

Bats Use Earth's Magnetic Field for Navigation

Hydrogen Bonds for New Magnets

A Two-Headed Fossil Reptile

A New Magnetic Chip Increases Computer Storage, Speed and Impedes Data Loss at Power Cuts

Birds Employ Earth's Magnetic Field for Navigation

Male Shortage and Global Warming

The Source of Stelar Magnetism

User opinions:

No user comments yet.

Be the first to express your opinion using the form below!

Share your opinion:

SUBMIT PROGRAM \| ADVERTISE \| GET HELP \| SEND US FEEDBACK \| RSS FEEDS \| ENTER NEWS SITE \| ENGLISH BOARD \| ROMANIAN FORUM
© 2001 - 2008 Softpedia. All rights reserved. Softpedia™ and the Softpedia™ logo are registered trademarks of SoftNews NET SRL.	Copyright Information \| Privacy Policy \| Terms of Use \| Update your software \| Archive