Our guinea pig, Robby (officially Robin) is eight and a half years old. My son told me the oldest guinea pig in captivity died at age 14 (he loves the Guiness Book of World Records). I'm guessing for guinea pigs in the wild the life span is about 2 minutes, given their poor eyesight, slow gait and inability to perceive height. Anyway, Robby is a much-loved part of our environment and we will miss him dearly when he is gone.
The children take care of him with very little direction from me. The older children teach the younger children how to hold Robby, how to pet him, how to give him food and water, and how to clean his cage (with gloves of course). They know they are needed and they rise to the occasion. Meaningful contribution is a necessary component of our perceived self-worth. The children realize their competence and it shows, not only in how they take care of Robby but in their approach to all the work they do.