Rapid colour change by the spider, Tylorida striata (Thorell, 1877) (Araneae: Tetragnathidae)

Although it has been known since the 19th century that the tetragnathid spider Tylorida striata has the capability of rapidly changing colour, descriptions of this to date have been limited to simply noting that it darkens in response to disturbance. The process of rapid colour change by this species is described here formally, both qualitatively and quantitatively, for the first time. Submergence in ethanol elicited no rapid colour change – demonstrating that the colour change is induced by a perceived environmental signal rather than a received physiological stress. This is also consistent with observations of modification of the response as a result of familiarisation. It is hypothesised that, in association with web-dropping escape behaviour, rapid colour change probably serves a cryptic function.