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| Titel: |
The Occurrence of Different Phase Angles Between Contrasting Seasons in the Activity Patterns of the Cave Harvestman Goniosoma spelaeum (Arachnida, Opiliones) |
| Auteur: |
Gnaspini, P. Santos, F. H. Hoenen, S. |
| Verschenen in: |
Biological rhythm research |
| Paginering: | Jaargang 34 (2003) nr. 1 pagina's 31-49 |
| Jaar: |
2003-02 |
| Inhoud: |
The cave harvestman Goniosoma spelaeum (Mello-Leitao, 1932) from southern Brazil has been studied in the field, in two contrasting seasons - summer and winter. This species is considered to be a strict trogloxene, which includes those animals that must both periodically leave the cave for food or reproduction, and come back to the cave (probably for its stable environment). Each animal was individually marked. Seven phases of the activity behavior were observed and analyzed: start of activity; displacement towards the cave entrance; exit to the epigean environment; epigean displacement for hunting/feeding; return to the cave; displacement inwards; and end of activity. To detect the influence of environmental features, relative humidity, light intensity and temperature were measured outside the cave, just at the entrance, and inside the cave. Our results suggest that the light/dark cycle should be the major environmental zeitgeber - in winter, exits occur earlier than in summer, because sunset occurs earlier, and returns occur later, because sunrise occurs later. However, the phase angle between activity and sunset/sunrise hours changes from winter to summer, sometimes including part of the light interval. This occurs especially with younger animals, which live close to the cave entrance. This fact suggests that there is probably a minimum time to forage that acts together with light/dark cycle, during summer, when the dark interval is shorter. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 11 van 11 gevonden artikelen
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