Well, man's best friend isn't going to be a sea monkey, is it? I mean, I bought the sea monkey kit, waiting excitedly for them to start dancing around in their top hats, and all they did was slowly simmer to death on my window cill throughout the summer months. No, I'm sure much more interaction and entertainment is to be had in the company of a dog.
Besides, dogs, like men, can be kept happy for hours on end chasing a ball around a field.
:-)