in a list*/
public void initIndividuals() {
this.listIndividuals = new CopyOnWriteArrayList<Individual>();
int startPositionX = INITIAL_POSITION_X;
this.spaceShip = new Ship();
this.alien1 = new Alien(new AlienType(1), startPositionX, POSITION_Y);
startPositionX += DELTA_X;
this.alien2 = new Alien(new AlienType(2), startPositionX, POSITION_Y);
startPositionX += DELTA_X;
this.alien3 = new Alien(new AlienType(3), startPositionX, POSITION_Y);
startPositionX += DELTA_X;
this.alien4 = new AlienMotherShip();
this.alien4.moveTo(startPositionX, POSITION_Y);
startPositionX += DELTA_X;
this.alienShot = new AlienShot(startPositionX, POSITION_Y);