The aerodynamic signature of running spiders.
Many predators display two foraging modes, an ambush strategy and a cruising mode. These foraging strategies have been classically studied in energetic, biomechanical and ecological terms, without considering the role of signals produced by predators and perceived by prey. Wolf spiders are a typical example; they hunt in leaf litter either using an ambush strategy or by moving at high speed, taking over unwary prey. Air flow upstream of running spiders is a source of information for escaping prey, such as crickets and cockroaches. However, air displacement by running arthropods has not been previously examined. Here we show, using digital particle image velocimetry, that running spiders are highly conspicuous aerodynamically, due to substantial air displacement detectable up to several centimetres in front of them. This study explains the bimodal distribution of spider's foraging modes in terms of sensory ecology and is consistent with the escape distances and speeds of cricket prey. These findings may be relevant to the large and diverse array of arthropod prey-predator interactions in leaf litter.
Casas
Jérôme
J
University of Tours, Institut de Recherches sur la Biologie de l'Insecte, UMR CNRS 6035, 37200 Tours, France. casas@univ-tours.fr
Steinmann
Thomas
T
Dangles
Olivier
O
D000818:Animals; D017753:Ecosystem; D004924:Escape Reaction; D006135:Gryllidae / Q000502:physiology; D008124:Locomotion / Q000502:physiology*; D011235:Predatory Behavior; D012420:Running / Q000502:physiology; D013112:Spiders / Q000502:physiology*