The equivalent of a tripwire that uses an invisible beam of light, typically infrared.

Not moulting, not shedding hairs or fur. / (botany) indehiscent, not shedding seeds or fruit.

Of, or relating to a predator. / Living by preying on other living animals. / (figuratively) Exploiting or victimizing others for personal gain.

To make a person or thing appear to be different than their true nature in order to fool someone else.