YOUNG CRICKETS' SUPERIOR ESCAPE RESPONSE

A cricket's mechanosensory hairs, which cover its cerci at the end of its abdomen, are literally lifesavers, picking up the telltale vibrations of a predator making its deadly approach. Since small crickets are more likely to become a predator's snack than larger ones, Olivier Dangles,Jérôme Casas and their colleagues measured the escape performance of small and medium sized juvenile and adult wood crickets (Nemobius sylvestris) for the first time in their natural environment(p. 3165). To take their experiment out of the lab and into the field, the team built a portable actuator connected to a piston, which they programmed to release a flow of air directly at the cerci that mimicked the approach of an attacking wolf spider. Filming the crickets' escape responses at 1000 frames per second to the air flow, they found that both groups of juveniles were more likely to respond than adults, and also much more likely to respond by jumping. Measuring the distance the crickets travelled in response to the air flow or to being touched by the piston, they found that adults moved a relatively smaller distance than the juveniles when escaping, and that juveniles responded faster. The team suspect that the juveniles' superior escape performance is to make up for the increased likelihood of them being preyed on, and also that many crickets wait until the last possible minute – when they are touched by the piston – before using their powerful back legs to escape by jumping.