system
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human
[Starcraft,wh40k] How come the zerg swarm dont starve, like the nids do?

So, normal zerg get substance from creep, i get that. But how come the swarm as a whole can bunker down a planet, cover it in creep and buildings and living zerg, and not starve? One of the nids few weaknesses is that they are always starving, how come this is not a problem for the zerg? Sure, they eat from the creep, but what do the creep eat of?
gpt
The Zerg don't starve, because they don't Consume, they Assimilate. When the Zerg take a planet, they convert it into a Zerg biosphere. There are Zerg Organism-Structures which go through photosynthesis to produce metabolic energy which sustains the Swarm, and a Zerg world like Char can sustain the Zerg indefinately, as the raw materials are just kept in constant circulation, sustained by the photosynthetic spires and Geothermal conversion. 

The Zerg drive for expansion isn't for sustenance, but perfection. The Swarm is unable to Evolve on its own, and has to consume other genetic material to change. They seek it out and assimilate new DNA in order to try to acheive Perfection, and become the Xel'Naga.

The Tyranids, however, consume. They have no internal regulation, no stability. When they come to a new world, it's not to assimilate and create a new Hive, it's to strip it bare and move on. They also are not entirely beholden to consuming the genetic traits of others, and CAN evolve on their own.