Relationship between compass systems of orientation in equatorial sandhoppers

Ugolini, Alberto

doi:10.1006/anbe.2001.1766

Cited by 25 publications

(21 citation statements)

References 16 publications

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“…For the experiments, we used an apparatus similar to the one employed by but slightly modified (Ugolini & Macchi 1988;Ugolini 2001). The sandhoppers were released in a transparent Plexiglas bowl (18 cm diameter) with 1 cm depth of seawater.…”

Section: Methodsmentioning

confidence: 99%

“…If the length of the mean resultant vector increased when data were multiplied by an index of more than one, the distribution was considered non-unimodal and automatically open in the points of the greatest separation between the sandhoppers' directions. The mean angles of the groups of direction thus formed were calculated separately (see also Ugolini 2001). Figure 1 shows that the young sandhoppers from the intrapopulation crosses (male Albegna´female Albegna and male Feniglia´female Feniglia) were quite well directed towards the respective sea-land directions of their parents' home beaches.…”

Section: Methodsmentioning

confidence: 99%

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Orientation at night: an innate moon compass in sandhoppers (Amphipoda: Talitridae)

Ugolini

Fantini

Innocenti

2003

Proc. R. Soc. Lond. B

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The supralittoral amphipod Talitrus saltator is well known for its capacity for astronomical orientation using the sun and moon as compasses. It has also been demonstrated that the sun compass is innate in this species. In our experiments, we released inexpert (naive) young born in the laboratory into a confined environment under the full moon and in the absence of the horizontal component of the magnetic field. They were allowed to see the natural sky and the moon only at the moment of release. The young individuals were obtained in the laboratory by crossing adult individuals from the same and different populations of sandhoppers. The young from intrapopulation crosses were well oriented towards the directions corresponding to those of their parents, whereas the young from interpopulation crosses were oriented in an intermediate direction. Therefore, our experiments demonstrate in the sandhopper T. saltator that sea-land moon orientation relies on an innate chronometrically compensated mechanism.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Orientation at night: an innate moon compass in sandhoppers (Amphipoda: Talitridae)

Ugolini

Fantini

Innocenti

2003

Proc. R. Soc. Lond. B

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“…The bowl and plate were mounted on a tripod and surrounded by a cylindrical screen 1e 3 cm higher than the water level, which blocked the sandhoppers' view of the surrounding landscape. To prevent the sandhoppers using the natural magnetic field as a compass cue to maintain a constant direction even in the absence of visual reference points (Arendse 1978), we equipped the device with a pair of suitably powered Helmholtz coils (diameter ¼ 64 cm, distance ¼ 35 cm) to cancel the horizontal component of the natural magnetic field (see Ugolini 2001 for further details). Releases were carried out under a full moon (lunar phase from 89 to 96%) and on moonless nights (new moon phase).…”

Section: Releases Under the Natural Skymentioning

confidence: 99%

Moon orientation on moonless nights

2007

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The sandhopper Talitrus saltator is known to use sun and moon compasses to return to the band of wet sand on a beach. The two compass systems are based on separate chronometric mechanisms that compensate for the azimuthal movement of the two astronomical cues. The aim of our research was to test whether the sandhopper's time-compensating mechanism for lunar compass orientation continues to work during the new moon phase (i.e. when the moon is not visible). Our tests were carried out in a confined environment under the natural sky and in the laboratory under artificial light, in both the full and new moon phases. Sandhoppers released in sea water headed towards the expected land direction of their home beach using the natural or artificial moon as a compass cue independently of the moon's natural phase, including the new moon phase. The sandhoppers' chronometric mechanism that compensates for the moon's azimuthal motion thus works continuously, even during the phase when the actual moon is never visible. This could be based on spatiotemporal interpolation between visible moon positions.

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“…Some of them, like celestial and astronomical cues, are of a general nature, whereas others are local. Among location-independent compass cues, many species of sandhoppers possess sun, moon and magnetic compasses (see Pardi and Ercolini, 1986;Ugolini, 2001a;Ugolini, 2001b;Ugolini et al, 2002;Ugolini, 2003). Local cues are also important: through learning, sandhoppers can modify the innate compass reference direction to improve their orientation along the sea-land axis direction or when they are displaced to a differently orientated beach (Ugolini and Macchi, 1988;.…”

Section: Introductionmentioning

confidence: 99%

Green land and blue sea: a coloured landscape in the orientation of the sandhopperTalitrus saltator(Montagu) (Amphipoda, Talitridae)

Ugolini

Somigli

Mercatelli

2006

Journal of Experimental Biology

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SUMMARY The use of the landscape in the zonal recovery of Talitrus saltator (Montagu) was demonstrated in the past using natural and artificial landscapes. Here we evaluate the importance of colour in the landscape orientation of sandhoppers. Adult individuals of T. saltator were released in a Plexiglas bowl under the sun, with a view of an artificial landscape: a black cardboard strip or a pair of differently coloured filters, each occupying 180° of the horizon. Our results not only confirm the influence of the black and white artificial landscape-based compass cue on the zonal orientation of T. saltator, but also show that vision of a blue and green artificial landscape affects the direction of orientation; in fact, the orientation agreed with the directional indication of the landscape even when it contrasted with the sun compass indication. The same result was obtained with a blue–grey and green–grey landscape, but not with pairs of grey filters. Therefore, in the sandhoppers'visual world, a coloured landscape that matches the prevalent natural field colours greatly contributes to their directional choice.

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Relationship between compass systems of orientation in equatorial sandhoppers

Cited by 25 publications

References 16 publications

Orientation at night: an innate moon compass in sandhoppers (Amphipoda: Talitridae)

Orientation at night: an innate moon compass in sandhoppers (Amphipoda: Talitridae)

Moon orientation on moonless nights

Green land and blue sea: a coloured landscape in the orientation of the sandhopperTalitrus saltator(Montagu) (Amphipoda, Talitridae)

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