public void destroyCritter(Critter item){
		synchronized(lock_critter){
			ListIterator<Critter> iter = play_pen.listIterator();
			Critter kill = null;
			while(iter.hasNext()){
				Critter temp = iter.next();
				if(temp.equals(item)){
					kill = item;
					break;
				}
			}
			if(kill != null){
				play_pen.remove(kill);
				System.out.println(kill + " dies");
			}
		}
	}