The use of polarized light in the zonal orientation of the sandhopper Talitrus saltator (Montagu)

Year: 2023

Authors: Ugolini A., Hariyama T., Wilcockson DC., Mercatelli L.

Autors Affiliation: Univ Firenze, Dipartimento Biol, Via Romana 17-19, I-50125 Florence, Italy; Hamamatsu Univ, Inst NanoSuit Res, Preeminent Med Photon Educ & Res Ctr, Sch Med, 1-20-1 Handayama,Higashi Ku, Hamamatsu 4313192, Japan; Aberystwyth Univ, Inst Biol Environm & Rural Sci, Penglais SY23 3DA, Aberystwyth, Wales; CNR, Ist Nazl Ott, Largo E Fermi 6, I-50125 Florence, Italy.

Abstract: It is well known that the celestial polarization is used as a compass cue by many species of insects and crustaceans. Although it has been shown that the sandhopper Talitrus saltator perceives polarized light and possesses an arrangement of the rhabdomeres that could allow e-vector interpretation and utilization, T. saltator does not use the e-vector of the skylight polarization as a compass cue when making excursions along the sea-land axis of sandy shores. We performed tests in confined conditions to clarify if skylight polarization is somehow involved in the zonal recovery of T. saltator. We observed the directional responses of sandhoppers in a transparent bowl under an artificial sky (an opaline Plexiglas dome). The bowl was covered by a blue gelatin filter with a grey filter (control condition) and a linear polarizing filter (experimental conditions) positioned under the blue one in such a way as to occupy half of the upper surface of the Plexiglas bowl so as to create a linear polarization gradient. Our experiments confirm that T. saltator perceives polarized light and highlight that this visual capability determines the perception, or perhaps the increase, of the radiance and/or spectral gradient and their use as compass cues in the zonal orientation. Moreover, our findings confirm that the radiance gradient is used as a chronometric compass orienting reference in the absence of other celestial orienting cues.

Journal/Review: ZOOLOGICAL LETTERS

Volume: 9 (1)      Pages from: 10-1  to: 10-7

More Information: Funding was provided by the University of Florence (UniFi RICATEN 2018—2019) assigned to AU and by JSPS KAKENHI Grant 22K18250 assigned to TH. We wish to thank the Ente Parco Naturale Regionale Migliarino S. Rossore Massaciuccoli (Pisa) for the permission to collect the sandhoppers.
KeyWords: Talitrus saltator; Skylight polarization; Celestial orientation; Radiance gradient; Spectral gradient
DOI: 10.1186/s40851-023-00207-8

ImpactFactor: 1.700

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