Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude
For animals that migrate long distances, the magnetic field of the earth provides not only a possible cue for compass orientation, but a potential source of world-wide positional information. At each location on the globe, the geomagnetic field lines intersect the earth’s surface at a specific angle...
Main Authors: | , |
---|---|
Other Authors: | |
Format: | Text |
Language: | English |
Published: |
1994
|
Subjects: | |
Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.9642 http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf |
id |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.489.9642 |
---|---|
record_format |
openpolar |
spelling |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.489.9642 2023-05-15T17:35:21+02:00 Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude Kenneth J. Lohmann Catherine M. F. Lohmann The Pennsylvania State University CiteSeerX Archives 1994 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.9642 http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.9642 http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf text 1994 ftciteseerx 2016-01-08T08:24:42Z For animals that migrate long distances, the magnetic field of the earth provides not only a possible cue for compass orientation, but a potential source of world-wide positional information. At each location on the globe, the geomagnetic field lines intersect the earth’s surface at a specific angle of inclination. Because inclination angles vary with latitude, an animal able to distinguish between different field inclinations might, in principle, determine its approximate latitude. Such an ability, however, has never been demonstrated in any animal. We studied the magnetic orientation behavior of hatchling loggerhead sea turtles (Caretta caretta L.) exposed to earth-strength magnetic fields of different inclinations. Hatchlings exposed to the natural field of their natal beach swam eastward, as they normally do during their offshore migration. In contrast, those subjected to an inclination angle found on the northern boundary of the North Atlantic gyre (their presumed migratory path) swam south-southwest. Hatchlings exposed to an inclination angle found near the southern boundary of the gyre swam in a northeasterly direction, and those exposed to inclination angles they do not normally encounter, or to a field inclination found well within the northern and southern extremes of the gyre, were not significantly oriented. These results demonstrate that sea turtles can distinguish between different magnetic inclination angles and perhaps derive from them an approximation of latitude. Most sea turtles nest on coastlines that are aligned approximately north–south, so that each region of nesting beach has a unique inclination angle associated with it. We therefore hypothesize that the ability to recognize specific inclination angles may largely explain how adult sea turtles can identify their natal beaches after years at sea. Text North Atlantic Unknown |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
ftciteseerx |
language |
English |
description |
For animals that migrate long distances, the magnetic field of the earth provides not only a possible cue for compass orientation, but a potential source of world-wide positional information. At each location on the globe, the geomagnetic field lines intersect the earth’s surface at a specific angle of inclination. Because inclination angles vary with latitude, an animal able to distinguish between different field inclinations might, in principle, determine its approximate latitude. Such an ability, however, has never been demonstrated in any animal. We studied the magnetic orientation behavior of hatchling loggerhead sea turtles (Caretta caretta L.) exposed to earth-strength magnetic fields of different inclinations. Hatchlings exposed to the natural field of their natal beach swam eastward, as they normally do during their offshore migration. In contrast, those subjected to an inclination angle found on the northern boundary of the North Atlantic gyre (their presumed migratory path) swam south-southwest. Hatchlings exposed to an inclination angle found near the southern boundary of the gyre swam in a northeasterly direction, and those exposed to inclination angles they do not normally encounter, or to a field inclination found well within the northern and southern extremes of the gyre, were not significantly oriented. These results demonstrate that sea turtles can distinguish between different magnetic inclination angles and perhaps derive from them an approximation of latitude. Most sea turtles nest on coastlines that are aligned approximately north–south, so that each region of nesting beach has a unique inclination angle associated with it. We therefore hypothesize that the ability to recognize specific inclination angles may largely explain how adult sea turtles can identify their natal beaches after years at sea. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Kenneth J. Lohmann Catherine M. F. Lohmann |
spellingShingle |
Kenneth J. Lohmann Catherine M. F. Lohmann Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
author_facet |
Kenneth J. Lohmann Catherine M. F. Lohmann |
author_sort |
Kenneth J. Lohmann |
title |
Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
title_short |
Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
title_full |
Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
title_fullStr |
Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
title_full_unstemmed |
Detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
title_sort |
detection of magnetic inclination angle by sea turtles: a possible mechanism for determining latitude |
publishDate |
1994 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.9642 http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.9642 http://www.unc.edu/depts/geomag/PDFGeomag/LL1994.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766134481840766976 |