Now we're going to add a "bad guy" -- a sea turtle. Everyone knows that turtles eat jellyfish. In fact, that's one of the reasons it's so bad for plastic bags to end up in the ocean - the turtles think they look like jellyfish and eat them and die.

Anyway, in this game the jelly is the good guy and the turtle is the bad guy.

We're going to be adding a number of behaviours:

• The turtle appears randomly
• Only ever one turtle at a time
• If the turtle touches the jelly, we lose a lot of health
• We slowly lose health even if nothing else is happening
• Every time we eat a fish, we regain some health
• The turtle also eats fish, if it gets to the fish before the jelly
• When health gets to zero, the game is over