The skylight gradient of luminance helps sandhoppers in sun and moon identification

Year: 2012

Authors: Ugolini A., Galanti G., Mercatelli L.

Autors Affiliation: Dipartimento Di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125 Firenze, Italy;
CNR – Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, Italy

Abstract: To return to the ecologically optimal zone of the beach, the sandhopper Talitrus saltator (Montagu) maintains a constant sea-land direction based on the sun and moon compasses. In this study, we investigated the role of the skylight gradient of luminance in sun and moon identification under natural and artificial conditions of illumination. Clock-shifted (inverted) sandhoppers tested under the sun (during their subjective night) and under the full moon (during their subjective day) exhibit orientation in accordance with correct identification of the sun and the moon at night. Tested in artificial conditions of illumination at night without the artificial gradient of luminance, the artificial astronomical cue is identified as the moon even when the conditions of illumination allow sun compass orientation during the day. When the artificial gradient of luminance is added, the artificial astronomical cue is identified as the sun. The role of the sky gradient of luminance in sun and moon identification is discussed on the basis of present and past findings.

Journal/Review: JOURNAL OF EXPERIMENTAL BIOLOGY

Volume: 215 (16)      Pages from: 2814  to: 2819

More Information: This research was funded by the Universita di Firenze (local funds ex-60%) assigned to A.U.
KeyWords: Moon compass; Orientation; Skylight gradient of luminance; Sun compass; Talitrus saltator; Amphipoda; Animals; Biological Clocks; Seawater; Sunlight, Talitrus saltator
DOI: 10.1242/jeb.069542

Citations: 15
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