27 January 2015

A Sea Turtle's Magnetic Voyage Back Home

Photo from www.arkive.org

Once they reach adulthood, sea turtles (e.g. Caretta caretta[1]), along with salmon and other marine mammals, travel thousands of miles across the open ocean only to return home to reproduce at the very coastal line where they hatched [2,3,4]. This amazing feat has baffled scientists for fifty years now [2].

Then how come they know their way home? New evidence points out that they “imprint” on magnetic fields as hatchlings and use these magnetic features as signature cues to return to their natal beach as adults [2,3]. Since early studies proved difficult in studying them in the open ocean, scientists took advantage of looking into changes in their behavior in response to changes in magnetic fields instead [2].

By processing a long-standing database, scientists found a strong link between the subtle shifts in the Earth’s magnetic field and the spatial distribution of the turtle nests. Only to confirm their theory: slight shifts in the Earth’s field resulted to coming together of adjacent magnetic signatures, hence gathering sea turtles in a much shorter coastline. Consequently, diverging magnetic signatures meant sparse eggs were laid and nests were farther from each other. This new evidence indicates that changes in magnetic fields influence where turtles will nest [2].

To learn more about sea turtles visit SeaLifeBase and to read more on salmons, visit FishBase.

[1] SeaLifeBase. Caretta caretta (Linnaeus, 1758). Retrieved January 27, 2015 from http://sealifebase.ca/summary/Caretta-caretta.html#.

[2] Cell Press. (2015, January 15). For sea turtles, there’s no place like magnetic home. ScienceDaily. Retrieved January 18, 2015 from www.sciencedaily.com/releases/2015/01/150115134713.htm

[3] Lohmann, K.J., Putman, N.F., Lohmann, C.M. (2008). Geomagnetic imprinting: a unifying hypothesis of long-distance natal homing in salmon and sea turtles. Proceedings of the National Academy of Sciences 105(49): 19096-19101.

[4] Putman, N.F., Lohmann, K.J., Putman, E.M., Quinn, T.P., Klimley, A.P., Noakes, D.L.G. (2013). Evidence of geomagnetic imprinting as a homing mechanism in Pacific salmon. Current Biology 23(4):312-316.

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