What device is placed under an animal's skin and can be read by a microchip scanner?

The device that is placed under an animal's skin and can be read by a microchip scanner is referred to as a transponder. Transponders are small, integrated circuits that typically come with a unique identification number. When a microchip scanner is passed over the area where the transponder is implanted, it emits a radio frequency signal that the scanner can read. This signal allows for the retrieval of the identification number, which is crucial for identifying lost pets and ensuring they can be reunited with their owners.

In the context of animal identification, transponders play a vital role in ensuring that pets can be identified quickly and accurately, reducing the time and complications involved in reuniting lost animals with their families. The terms chip, tracker, and identifier can have various meanings but do not specifically capture the functionality and definition of the device used for pet identification as accurately as transponder does.