Study
Geomagnetic map used in sea-turtle navigation
Lohmann, Kenneth J.; Lohmann, Catherine M. F.; Ehrhart, Llewellyn M.; Bagley, Dean A.; Swing, Timothy
Nature, 2004
Juvenile green turtles from a feeding ground were tethered in a water arena surrounded by coils reproducing the magnetic fields of sites well to the north and south of their capture location, and their swimming directions recorded.
- Studied in
- Chelonia mydas
- Sample size
- juvenile green turtles tested in magnetic coil systems
Turtles exposed to the field of a northern site swam south, and those exposed to a southern field swam north — in each case towards their actual home area.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Turtles can derive positional information from the geomagnetic field and use it to steer towards a known location.
How NatureHQ reads it
A map result rather than a compass result, and the design is what makes it one: the animals were not displaced, so the only thing telling them they were somewhere else was the field itself. What it does not show is the receptor, which remains unidentified in turtles as in birds.
- Tethered juveniles in an arena; the behaviour is a swimming direction, not a journey.
- Two simulated locations, both within the range the animals plausibly know.
Showing a turtle the magnetic field of a place it is not
Can an animal work out where it is from the magnetic field alone — not which way to point, but where it is?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Sea turtles
Put a turtle in a tank and reproduce the magnetic field of a place hundreds of kilometres north of where it actually is, and it swims south — towards where it would need to go if it really were there.
Sea turtles
Nesting turtles follow the magnetic signature of their natal coast, and that signature drifts. Where neighbouring stretches drifted together, turtles crowded in; where they drifted apart, nesting thinned.
Published by: Nature PortfolioPublished in a Nature Portfolio journal.
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.