The Sun, the Moon, and the Sandhopper

Moon orientation on moonless nights

“…Our results, and previous findings, clearly show that an artificial light source is used at night as if it were the real moon; furthermore, this is largely independent of the light source's intensity and spectral composition or the phase of the real moon (Ugolini et al 2002a(Ugolini et al , 2005). In our experiments, the artificial light source was never mistaken for the sun, since sun compensation at night is based on a mechanism that involves the sun returning to the east after sunset and passing from the south (Talitrus model) instead of from the north (Apis model; Pardi & Ercolini 1986;Ugolini et al 2002b).…”

“…Despite its lack of a circatidal activity rhythm (Williams 1979), T. saltator is among the few arthropods in which a moon compass has been demonstrated: sandhoppers use the moon and sun as compass cues to steer the correct and shortest route along the seae land axis of their home beach (Papi & Pardi 1953;Pardi & Ercolini 1986;Ugolini et al 1999aUgolini et al , 2002a.…”

“…zonal recovery) is shared by many arthropods of different taxa living in the same or similar habitats (ecotonal environments, see Campan 1997). This zonal recovery is mainly based on the ability to compensate chronometrically for the azimuthal variation of the sun and moon to maintain (theoretically constant) the seaeland direction of orientation throughout the day and night (reviewed in Pardi & Ercolini 1986;Ugolini et al 2002a;.…”

“…The use of the moon as an orienting factor, the existence of a moon compass and of separate chronometric mechanisms for sun and moon compensation, and the use of an artificial light source to reproduce good moon orientation have already been demonstrated in sandhoppers (Pardi & Papi 1952;Pardi & Ercolini 1986;Ugolini et al 1999aUgolini et al , 2002aUgolini et al , 2005). The aim of our research was to test whether the sandhopper's time-compensating mechanism for lunar compass orientation continues to work when the moon is invisible (during the new moon phase).…”

Optic flow and sea - land orientation in the sandhopper Talitrus saltator (Montagu)

“…Sandhopper y-axis orientation is based on bi- directional movements without the need for place memory: sandhoppers do not have a 'home' and are not central place foragers. These bi-directional movements are mainly guided by local cues, such as the surrounding panorama (Williamson, 1951;Williamson, 1954;Craig, 1973;Hartwick, 1976;Edwards and Naylor, 1987;Ugolini et al, 1986;Ugolini and Cannicci, 1991), and by compass cues, such as the sun, the moon and the geomagnetic field (Ugolini, 2001;Ugolini et al, 2002;Ugolini et al, 2003), whereby the directional choice of sandhoppers also makes use of the spectral differences between the landward and the seaward part of the panorama (Ugolini et al, 2006).…”