Complex global behaviour may emerge from the interaction of tadpoids that have a few self-determined behaviours. By altering a single behavioural parameter one observes that the entire interaction of the tadpoids alters in ways which would at first appear unrelated to the initial change.
A single change within a complex system has knock-on effects, which even with a thorough knowledge of the components of the system is hard to predict. For example, by increasing the maximum possible speed of the tadpoids, the movement of the flock is not a faster version of the slower flock. Also, by increasing the distance that tadpoids need to be within other tadpoids, does not result in a similar flock with the tadpoids spaced further apart, but creates an altered state that has far reaching effects on the individual interactions and hence the global behaviour.
By using the pull of the flock algorithm this allows for natural looking, realistic flocking to emerge. This is because each tadpoid has a choice on where to head based on its individual perception of the environment and the tadpoids head for other tadpoids, whereas using the Reynolds centring algorithm each tadpoid when 'out-flock' is forced to a given heading - the average position of the flock. This position could be where there are not any tadpoids, so is an unnatural method.
By strategically controlling the predator's movement, a user may learn to coerce the tadpoids and maybe even herd them into a pen. However, if the tadpoids flocking algorithm is removed, the task of trying to 'round-up' the tadpoids increases in difficulty as they have to be penned more or less one by one.
The introduction of the predator's influence upon a tadpoid as a summative effect allowed the tadpoid to evade the predator while simultaneously seeking the safety of the flock.
