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Background. The ‘whirling’ defensive behavior of Pholcus ancoralis (L. Koch, 1865) was studied in a forest and laboratory in Mo’orea, French Polynesia. This behavior involves fast web-borne gyration to dissuade predators and is widespread in the Pholcidae family.
Methods. Different local predators (Anterhyncium rufipes, Lipinia noctua, and Thorelliola ensifera) were placed in two-chambered systems with P. ancoralis individuals and qualitative data on whirling frequency and duration were obtained.
Results. Potter wasps (Anterhyncium rufipes) triggered whirling in 50% of trials and moth skinks (Lipinia noctua) triggered whirling in 20% of trials. The average durations of the behavior triggered by each were 853 and 455 seconds, respectively. Pacific horned jumping spiders (Thorelliola ensifera) triggered whirling in 10% of trials with an average duration of only 20 seconds.
Discussion. Wasps triggered whirling the most frequently and of a long average duration. This has not been seen in other studied pholcids. This difference in predator specificity of whirling may be due to differences in habitat between pholcid species.