There are 4 animals in this demo like the other demos. There are 2 animals that can perform in shows, the Bottlenose Dolphin and the Orca as well as 2 other animals, the Rockhopper Penguin and the Green Sea Turtle. The player can buy marine-themed objects and can make shows just like the full game. But there is a glitch that is common in this demo that causes guest's heads to disapear.
Some designers have been able to steal the Marine Mania .nif files from the demo, which allowed them to mesh Marine Mania. Eventually, however, the nifs became available for everybody to use.