These are 3 different machanical animals. They are all pretty basic mechanical devices that turn rotary motion into more of a linear motion. My kids (and their friends) have gotten a real kick out of them. I drew them all in sketchup.

Jumping Prairie Dog Turn the crank and make the prairie dog jump up and down.

Diving Dolphin Turn the crank and watch the dolphin dive through the waves.

Wood Pecker Turn the crank and see the wood pecker peck away. (This was originally posted as a pecking bird, but my kids all call it the woodpecker, so I'm putting it up as part of this collection).