It's what's known as a bioluminescent burglar alarm, and just like the alarm on your car or your house, it's meant to cast unwanted attention onto the intruder, thereby either leading to his capture or scaring him away.
Es lo que se conoce como alarma bioluminiscente antirrobo. Al igual que la alarma del auto o de la casa está diseñada para llamar la atención sobre el intruso para, de ese modo, llevarlo a la captura o ahuyentarlo.