The turtles can perceive both the magnetic field’s intensity and its inclination angle, the angle that the field lines make with respect to the Earth’s surface, earlier research has shown.
By using previously reported genetic information from more than 800 nesting Florida loggerheads, Dr. Lohmann and Mr. Brothers were able to show that there was more genetic similarity among turtles that nest on beaches with similar magnetic signatures than there was among turtles that nest on beaches that were physically close to each other.
“We expect that geographically close locations will be genetically related, and geographically distant locations will have distinct populations. That’s not what we see,” Mr. Brothers said. “The variation in earth’s magnetic field around the nesting area seems to really predict genetic differentiation much better than geographic distance.”
It’s also a better predictor than environmental conditions like beach temperature, he said.
Loggerhead turtles are known to nest on Florida’s Gulf as well as Atlantic coasts, with some apparently nesting on both sides of the peninsula at different points in their life, Mr. Brothers said. With magnetic fields running across the peninsula, individual turtles might be making navigational errors and nesting on beaches that are magnetically similar to their home beach, but on opposite coasts, he said.
Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up You agree to receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters.
Dr. Lohmann said that conservation efforts in Bermuda, where there have been unsuccessful attempts to restore sea turtle populations driven to extinction centuries ago, might benefit from considering this geomagnetic imprinting.
Theoretically, turtles might be encouraged to nest on certain beaches if the magnetic field of hatchlings were manipulated to convince them that they were born in a different location.
The current study is based on genetic data, not experimental evidence, but Dr. Lohmann said a more definitive study would be too challenging to undertake. Sea turtles don’t begin to reproduce until they are about 20, and only one out of 1,000 hatchlings survives to reproduce, so scientists would need to run an unrealistically long and large experiment, he said.
Even without being definitive, the new research is still useful, said Nathan Putman, a senior scientist at LGL Ecological Research Associates Inc. in Bryan, Tex., who was not involved in the study.
“Understanding very fundamental and basic aspects of the organism’s navigational decisions gives you a lot more information,” he said.
MayIServeYouWell on April 14th, 2018 at 05:41 UTC »
I wonder how these animals perceive this sense? Is it like they're operating with a big map in their head, and they can just kind of tell where they are on it? Just as I navigate from room to room in my house, knowing its every turn and nook, they circle the globe.
Drak_is_Right on April 14th, 2018 at 02:18 UTC »
Is this at all like how birds have a protein that allows them to see magnetic lines?
edit: the protein isolated that allows a species of birds to "know" the magnetic fields is located in their eyes and seems tied also to availability of light. still a lot more research to be done, but it could very well be along the same lines.
https://cosmosmagazine.com/biology/birds-may-see-magnetic-field-with-help-of-eye-protein
marcusregulus on April 14th, 2018 at 01:49 UTC »
Can this correct? The magnetic poles drift around, and at a much faster rate than continental drift. The poles have even flipped many times. Turtles must have additional ways to navigate correctly besides magnetism.