Officials say the girls, ages 14 and 15, twice put their hamster, named Bugsy, in a microwave. Police say they also stuck Bugsy in the freezer.
Officer Carl Miller says the girls told authorities they just wanted to see the hamster go around on the microwave's plate. The girls told authorities that they didn't think the animal would be hurt because it was only in there about five seconds.
Animal Control officers say the hamster survived, but chewed off three of its feet that were burned and blackened.
The girls, whose identities have not been released because of their ages, are being held in Juvenile Hall.