system
Given the following post, respond as if you're commenting on Reddit:
human
[Starcraft] What do the zerg eat?

It seems like an entire race of apex predators which must consume massive amounts of calories to keep running.

What do they eat? They must all be carnivores and spend most of their awake time eating. Is the creep edible? Like some massive fungus colony?

I'm thinking that prey must be a crucial requirement for any zerg campaign, just as fuel is for terrans.
gpt
Creep handles most of the Zerg's ground-based logistics. It leeches minerals and nutrients from the soil, as well as consumes any biological matter it comes across. Whether that be living animals, dead bodies, or even other Zerg that the hivemind has chosen to sacrifice. These nutrients and other resources are spread via a complex series of capillaries and nearly invisible connection points into every single zerg, structure or unit, that contacts it. 

Many Zerg battle forms, such as the Zergling, are often meant to survive only a short time, so are hatched with all the nutrients they need to endure a single battle before dying. In an ideal scenario, their corpse will be consumed by the creep, and the components redistributed into other Zerg functions.  However, if they absolutely must, many Zerg forms can also hunt prey and have a functional (if basic) digestive system if they must survive for long periods of time away from creep. Those without mouths usually aren't capable of doing such a thing, and are wholly dependent on creep and/or the whim of the swarm to stay functional. 

Creep is not edible, either by the Zerg or by humans. Human digestive systems are nowhere near robust enough to break down creep's cellular structure, and so eating a portion of it would likely cause it to begin spreading inside the stomach. Leading to a gruesome and painful death.