Behavioural evidence for the use of geomagnetic cue in Japanese glass eel Anguilla japonica orientation

Japanese eel is already magnetosensitive at the glass eel phase. However, currently, there is no evidence that they can use geomagnetic cues for orientation. We examined orientation behaviour in a radially symmetrical test arena in which the horizontal component of the geomagnetic field could be manipulated. Groups of glass eels released at the centre of the arena showed a mean orientation angle significantly biased to the south of 198A degrees in the ambient geomagnetic field, but showed random orientation in the geomagnetic field when its horizontal component was cancelled in a solenoid. Results showed that they use geomagnetic cues for orientation.