Thanks KAK and Popcornbird!

KAK, when I was little I had several pairs of the brown gerbils. I think they only came in one color back then.
It wasn't until I was in college that I saw black ones and brought a pair home from college with me.

Popcorn, T-bird is interested in the gerbils when they roll around in the ball. They like to roll under her cage a lot because of all the seeds she drops.
Samantha didn't actually notice the gerbils until two days ago. I took a couple of photos of her meeting one of them in the ball.
I hope to post the photos this weekend sometime. She is being a very good big sister.