I would consider the Animal class to be obsolete. Methods have been added directly into the Actor class to perform the 'canSee' (see 'isTouching') and the 'eat' (see 'removeTouching'), as well as the 'atWorldEdge' (see 'isAtEdge') method. This leaves the 'move' method which uses the 'WALKING_SPEED' field, where the field is a class constant. As such, all objects of all subclasses must use that same speed. That gives a heavy restriction on the 'move' method of the Animal class. So, you can see that there really is no usefulness in any Actor class to have the Animal class as a superclass. Having the shells destroy the bombs is simply having the shells 'eat' the bomb that it 'canSee' (or removing a bomb that is touched). In this case, however, you may also want the shell removed when it removes a bomb. Having the tank create a shell requires a trigger (what causes the creation of a shell -- or what triggers a shell to be fired). The tank will be doing this action, so the act method of the class of the tank would be the appropriate place for the code (or in a method that act method calls). Depending on what is used for the trigger, you may have to regulate the rate of shell firing.

Hey I got it down. I used a firing method similar to that of Greenfoot Space Invaders. From there I used the animal class to make the shell eat the bomb then a destroy command.