Kandrona rays are yeerks food. They feed by absorbing them through their skin. Kandrona rays are beamed through a kandrona ray/particle generators into the yeerk pool, or on the Yeerk homeworld from the natural sun. Later it was revealed that the Iskoort also feed off of Kandrona rays. Yeerks and Iskoorts need to feed off of Kandrona rays everythree days.