Desert Locust

Desert locusts exhibit dramatic phenotypic plasticity, existing in two radically different forms: a solitary phase (brown, avoids other locusts) and a gregarious phase (yellow, swarms with millions of others). The transformation is triggered by physical contact - if a young locust bumps into others frequently (indicating crowding), it develops into the gregarious form. The switch takes a single generation.

This example shows how environmental signals (touch frequency) can trigger complete behavioral and physical transformation without genetic change, illustrating the power of phenotypic plasticity for rapid environmental response.