What unique behavior do some pillbugs exhibit when disturbed?

Pillbugs, often referred to as roly-polies, exhibit the unique behavior of rolling into a tight ball when disturbed. This defensive mechanism is an evolutionary adaptation that protects them from potential predators. By curling up, they expose less of their body to danger, making it more difficult for a predator to catch or eat them. This behavior also helps to retain moisture, which is crucial for their survival since they are terrestrial crustaceans and can be susceptible to drying out. The action of rolling into a ball is quite distinctive and allows them to minimize physical vulnerability in threatening situations, effectively serving as a form of shelter.

Other behaviors such as potentially emitting a foul odor or changing color are not typical responses to disturbances, and while some insects may have chemical defenses or camouflage strategies, these do not apply in the case of pillbugs. Additionally, the capability of flying away is not characteristic of pillbugs, as they lack wings and therefore cannot fly. This focus on their unique curling behavior explains their specific adaptation to environmental and predator challenges they encounter.