title: Crypsis via leg clustering: twig masquerading in a spider.
abstract: The role of background matching in camouflage has been extensively studied. However, contour modification has received far less attention, especially in twig-mimicking species. Here, we studied this deceptive strategy by revealing a special masquerade tactic, in which the animals protract and cluster their legs linearly in the same axis with their bodies when resting, using the spider Ariamnes cylindrogaster as a model. We used cardboard papers to construct dummies resembling spiders in appearance and colour. To differentiate the most important factors in the concealment effect, we manipulated body size (long or short abdomen) and resting postures (leg clustered or spread) of the dummies and recorded the responses of predators to different dummy types in the field. The results showed that dummies with clustered legs received significantly less attention from predators, regardless of the body length. Thus, we conclude that A. cylindrogaster relies on the resting posture rather than body size for predator avoidance. This study provides, to the best of our knowledge, empirical evidence for the first time that twig-mimicking species can achieve effective camouflage by contour modification.
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Shichang
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Kuei-Kai
authors.initials: KK
authors.lastname: Mao
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Po-Ting
authors.initials: PT
authors.lastname: Lin
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Chiu-Ju
authors.initials: CJ
authors.lastname: Ho
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Wei
authors.initials: W
authors.lastname: Hung
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Dakota
authors.initials: D
authors.lastname: Piorkowski
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan.
authors.forename: Chen-Pan
authors.initials: CP
authors.lastname: Liao
authors.affiliation: Department of Life Science, and , Tunghai University , Taichung 40704, Taiwan ; Center for Tropical Ecology and Biodiversity , Tunghai University , Taichung 40704, Taiwan.
authors.forename: I-Min
authors.initials: IM
authors.lastname: Tso
keywords: Ariamnes cylindrogaster; camouflage; contour modification; crypsis; twig-mimicking