From the Super Mario Wiki, the Mario encyclopedia
The player must control the tilting platform in the middle and direct it left or right. A creature will fall and the player must sort it in the correct section: the left section (ocean) or the right section (desert). Such creatures can include otters, crabs, and penguins (which should fall on the ocean side); and scorpions, cacti, and cobras (which should go to the desert). If a creature is placed in the wrong side, it will freeze or dry up.