A computerised method to observe spider web building behaviour in a semi-natural light environment

Spider webs are a record of the application of a series of behavioural patterns. Web building behaviour is of great interest to ethologists and taxonomists studying the evolutionary relationships of spiders. However, due to the inability of the researcher to observe the spider around the clock during web building, many details of the behavioural patterns remain undetected. To overcome this problem we developed a novel, computerised method to continually observe the spider during web building. The spider is kept in a temperature controlled room, on a reversed light cycle, confined to an observation arena placed in front of an infrared illuminated background. An infrared sensitive digital video camera is used to capture live images which are transferred to a computer where they are analysed in real time. A separate program allows a detailed study of the recorded movements, including various spatial and temporal analyses. It also allows for the export of movement patterns. The method of observation and data analysis developed by us, enables the detailed study of the web building behaviour of nocturnal spiders and eliminates most constraints encountered to date. Due to the inaccuracy of human observation of long chains of behavioural events and the stereotypic nature of web building behaviour, computerised observation systems are preferable.