The journal Current Zoology (formerly Acta Zoologica Sinica) has just published a special issue on The Evolution of Mechanisms Underlying Behaviour’, partly inspired by the 2013 Association for the Study of Animal Behaviour’s Winter Meeting on the same topic. I was kindly invited to contribute an article to this issue and decided to review behavioural flexibility and cognition in orb spiders during web-building. I was particular interested in addressing the question of how spiders assess the structure of their web-site during their exploration behaviour prior to beginning web-building proper. This is a question that has interested me for several years now (and undoubtedly will for many more to come), but which sadly lack solid experimental evidence. In this therefore somewhat speculative review paper, I discuss two extreme hypotheses of what type of information the spiders gather during the exploration behaviour. The very cognitive demanding ‘cognitive map hypothesis’ suggests that spiders gather metric spatial data and forms a simple cognitive map of their surroundings during the exploration behaviour, while the cognitive simple ‘stigmergy hypothesis’ suggests that spiders somehow utilise the threads laid during exploration behaviour to inform them of the quality of the site perhaps combined with simple binary yes-no information on the presence of obstacles.
Hesselberg, T. (2015). Exploration behaviour and behavioural flexibility in orb-web spiders: A review. Current Zoology 61, 313-327.
http://www.actazool.org/paperdetail.asp?id=12440 (Open Access)
Abstract:
Orb-web spiders and their webs constitute an ideal model system in which to study behavioural flexibility and spatial cognition in invertebrates due to the easily quantifiable nature of the orb web. A large number of studies demonstrate how spiders are able to modify the geometry of their webs in response to a range of different conditions including the ability to adapt their webs to spatial constraints. However, the mechanisms behind this impressive web-building flexibility in these cognitively limited animals remain poorly explored. One possible mechanism though may be spatial learning during the spiders’ exploration of their immediate surroundings. This review discusses the importance of exploration behaviour, the reliance on simple behavioural rules, and the use of already laid threads as guidelines for web-building in orb-web spiders. The focus is on the spiders’ ability to detect and adapt their webs to space limitations and other spatial disruptions. I will also review the few published studies on how spatial information is gathered during the exploration phase and discuss the possibility of the use of ‘cognitive map’-like processes in spiders. Finally, the review provides suggestions for designing experimental studies to shed light on whether spiders gather metric information during the site exploration (cognitive map hypothesis) or rely on more simple binary information in combination with previously laid threads to build their webs (stigmergy hypothesis).
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