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.

Colour matching in an orb‐web spider: a twig‐masquerading species as seen by potential predators

“…Tseng et al ., ). The combination of morphology, behaviour and colour matching in masqueraders seems to be an efficient way to deceive diurnal predators (Zhang et al ., ). However, several aspects of masqueraders ecology still wait to be assessed (Skelhorn et al ., ).…”

“…Therefore, the function of masquerade is to lead the predator to misclassify and not to preclude detection as in crypsis (Skelhorn et al ., ). Although masquerade has been addressed by recent studies (Skelhorn et al ., ; Pekár, ; Zhang et al ., ), its principle of action still needs to be clarified regarding the role of colour in such misclassification (Skelhorn et al ., ). There are different classes of masquerade, considering the dependence of colour matching to some specific object (Skelhorn et al ., ).…”

Multifunctionality of an arthropod predator’s body coloration

“…The evolutionary significance of different spider body colours is still a matter of conjecture. Some spiders use their body coloration to attract mates (Lin, Zhang, Liao, Hebets, & Tso, 2015), as prey lures (Blamires et al, , 2012Tso, Zhang, Tan, Peng, & Blamires, 2016;White & Kemp, 2016;Zhang, Chen, et al, 2015a), to avoid (Bonte & Maelfait, 2004;Brechbuhl, Casas, & Bacher, 2010;Bush, Yu, & Herberstein, 2008;Hoese, Law, Rao, & Herberstein, 2006), startle or confuse predators (Liu, Blamires, Liao, & Tso, 2014;Moya-Lorano, Taylor, & Fernandez-Montraveta, 2003;Zhang, Mao, et al, 2015b), for thermoregulation (Robinson & Robinson, 1978), or perhaps a complex interplay of these functions. Most of what is known about the function of spider body colours emanates from studies of single features, for example conspicuous bright stripes or spots (Blamires et al, 2012;Tso et al, 2016).…”

Estrutura da teia e estratégias de defesa de Wixia abdominalis O. Pickard-Cambridge, 1882 (Araneae, Araneidae)

“…Therefore, the function of masquerade is to lead the predator to misclassify the visual recognition of the prey and not to preclude detection as in crypsis (Skelhorn et al 2010). Although masquerade has been addressed by recent papers (Skelhorn et al 2011, Pékar 2014, Zhang et al 2015, its principle of action still need to be clarified regarding the role of colour in such misclassification (Skelhorn et al 2010).…”

“…Simon, 1889 (Theridiidae), achieve defensive success mainly by means of appropriate postures associated with their unusual body shape (Zhang et al 2015). Species presenting this colour matching-independent masquerade are referred to as "object imitators", and can be misclassified by predators in a wide range of backgrounds (Skelhorn et al 2010).…”