Animating an image within a layer mask

The beauty of this technique is that although you change the layer object position, the mask stays in place. Here, you’ll start the next phase of the animation process by moving the image of the tail itself. As you do this, the gradient mask won’t change, so it will have the same effect on the visibility of the whale as it sinks and rises in and out of the water.

1.	In the Animation palette, click the Duplicate Current Frame button (). Leave frame 2 selected.
2.	Select the Move tool (), and make sure that Layer Selection () is selected in the tool options bar.
3.	In the image window, drag the tail image down until it almost disappears below the surface of the water.
4.	In the Animation palette, drag frame 2 left, so that it becomes the new frame 1.