Guinea Pig
Surprise—this little piggy's not a pig! Guinea pigs are also called cavies (KAY-veez). In the wild, they live in South American mountains and grasslands. Descended from wild cavies, pet piggies are friendly and fun to watch. They yawn when mad and rub their rumps on things to signal, "That's mine!" Provide them with plenty of fresh hay for nesting and snacking. Sometimes you'll catch guinea pigs popping their own poo pellets in their mouth. Yuck! For them, it's like a vitamin. Click here to watch a video on pet guinea pigs.

Hamster
To keep hamsters happy, it helps to understand their wild relatives. Hamsters naturally live in underground tunnels. That's why pet hamsters need lots of bedding to dig through. Shredded white paper and hay are best. Avoid pine or cedar shavings; they can cause breathing problems. Hamsters are active at night, so it's best if their cages aren't in your bedroom. Otherwise, you won't get much sleep! Click here to watch a video on caring for hamsters.

Rat
Like wolves, sharks, and spiders, rats get a lot of unfair knocks. But these supersmart critters make excellent pets. Although many people think rats are dirty, they're actually quite clean. They constantly groom themselves and especially appreciate a clean cage. Because they're so smart, rats need lots of fun toys and attention. Most rats love to be petted and gently scratched. You can even train them to fetch, sit, and walk a tightrope!