Sky radiance and spectral gradient are orienting cues for the sandhopper Talitrus saltator (Crustacea, Amphipoda)

Year: 2021

Authors: Ciofini A., Mercatelli L., Hariyama T., Ugolini A.

Autors Affiliation: Hamamatsu University School Of Medicine · Department of Biology, Dipartimento di Biologia UniFi

Abstract: The sandhopper Talitrus saltator relies on both the sun and the moon
compasses to return to the belt of damp sand on the beach in which it
lives buried during the day. In addition to the sun, the gradient of
radiance and the spectral distribution across the sky could provide
directional information that T. saltator can potentially use to orient
itself during the day even when the sun is not visible (e.g. cloudy sky).
The scope of this work was (1) to determine the intensity levels of sky
radiance that the sandhoppers use in their zonal recovery and (2) to
investigate whether this species relies on the celestial spectral
gradient in its zonal recovery. Sandhoppers were tested in the
laboratory under artificial radiance or spectral gradients. Our results
show that under an artificial sky simulating the natural radiance
gradient on a cloudless day, sandhoppers orientated toward the
correct seaward direction of their home beach; however, individuals
lost their ability to use the intensity gradient as an orientation cue
when the radiance was attenuated by at least 40%. Sandhoppers
were also able to head in the correct seaward direction of their home
beach at any time of the day by using the spectral gradient as their
only source of visual orientation reference.


Volume: 224      Pages from: 1  to: 7

KeyWords: Sky radiance, Spectral gradient, Orientation, Sandhopper, Talitrus saltator
DOI: 10.1242/jeb.239574