Adult individuals of Talitrus saltator were tested for celestial orientation in a plexiglass bowl covered with colour filters of different wavelengths. Results show that T. saltator can recognize the sun and use it for orientation only at γ <450 nm. At γ >500 nm, the sight of the sun (and sky) only induces phototactic behaviour. It has also been confirmed that an important celestial orienting factor is perceived in the UV range. Variations in populations from diversely oriented coastlines are discussed. Preliminary results of electroretino-graphic responses indicate the presence of at least two visual pigments in the eye and a steep decrease in sensitivity for γ >500 nm.

We studied the capacity for zonal recovery in an equatorial sandhopper, Talorchesfia tricornuta, inhabiting the sandy beaches of equatorial West Africa. These beaches are often narrow and backed by an evident landscape. The sky usually has heavy cloud cover. The expenments were performed both in a confined environment and in the field, in full sun or an overcast sky, with the magnetic field natural, deviated or absent T. tricomutn was able to assume the correct direction using the sun and magnetic field as orienting factors. Moreover, the releases in the field with the natural landscape visible indicate that the landscape may constitute a further important orienting factor in zonal recovery.

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