Imagine a damp forest floor with a toad sitting motionless by a log. An insect scuttles from under the log, moving too fast to identify, and immediately the toad lunges towards the insect, flicking its tongue towards it. The toad misses its meal this time and the insect swivels away from the lunge of the toad and runs for cover; it was a cockroach (Fig. 3.1). These two behaviours, prey capture by toads and escape running by cockroaches, are excellent case studies in neuroethology because both show how it is possible to identify the roles played by individual nerve cells in recognising significant stimuli and triggering appropriate behavioural responses. In these cases, the stimuli require immediate action on the part of the animal. A toad will in fact try to catch and eat any small animal that moves along the ground in front of it; it probably does not hunt for cockroaches in particular. Likewise a cockroach will turn and run away from rapidly accelerating air currents, such as those produced by the sudden strike of any predator including a toad. Toads and cockroaches are not specifically adapted to detect each other, but natural selection has shaped the evolution of effective neuronal mechanisms that enable toads to recognise scuttling insects as a potential meal and cockroaches to escape from predatory assaults. In each behaviour, the animal needs to assimilate sensory information rapidly and to organise its motor response appropriately.