public void detectOther(Sprite other) {
        if(isRemovable) return;
        if( other == detected) return;
        detected = other;
        if(getCenter().distance(other.getCenter()) <= 
            getWidth() / 2 + other.getWidth()/2){
            collide(other);
            other.collide(this);
        }else{
            if(other instanceof Prey)other = (Prey)other;
            if(other instanceof Predator)other = (Predator)other;
            other.detectOther(this);
        }
    }