MAGNETIC ORIENTATION BY HATCHLING LOGGERHEAD SEA-TURTLES (CARETTA-CARETTA)

Laboratory experiments were conducted to test the ability of loggerhead sea turtle hatchlings (Caretta caretta L.) to orient using the magnetic field of the earth. Hatchlings were tethered to a rotatable lever-arm apparatus which tracked swimming orientation in complete darkness. Hatchlings tested in the earth's magnetic field were nonrandomly oriented with a mean angle of 42-degrees; those tested under an earth-strength field with a reversed horizontal component were also nonrandomly oriented, but with a mean angle of 196-degrees. The distributions under the two magnetic field conditions were significantly different, indicating that loggerhead sea turtle hatchlings can detect the magnetic field of the earth and use it as a cue in orientation.