So many of them so fast! Perhaps you could add some lives to restart? Also after I died it I think it continued to try and make the zombies, you might want a boolean if statement to check if the game is over. :)

Phew, tough dodging so many whales but was able to do it! Perhaps it could keep a counter of the amount of worms caught? http://greenfoot.org/scenarios/files/MiksAsteroids.zip has a scenario with a lot of details on that.

I think you might want to alter your choice of keys for moving around, I get very confused trying to figure out what keys to use. Usually A => look left, d => look right, s => go down, w => go forward. Obviously that can be played with, but trying to maintain that four button appearance aids a lot of people. You might also want to look about adding something to the yellow block to show the current direction you are facing (or not depends on how difficult you plan to make it ;)

Love the little messages put when I mess up :) Very hard to get the angles right with the turns. But I guess that is part of the gameplay factor :)