Starfleet Jedi

Do Tyranids in 40K continue to live in Galaxies they have already swarmed, or to they just move on?

As far as I know, they consume everything and then move on to consume more of... everything.

("Everything" here means "everything alive").

Yeah, they turn a planet's biomass and water into a broth of some kind and slurp it with giant biostraws, all that with a fleet of billion of units and over a hundred days.
It is said that the Astronomican is a beacon that attracts them, but since its range is limited, it's hard to tell if there are more Tranids elsewhere.

Mr. Oragahn wrote:Yeah, they turn a planet's biomass and water into a broth of some kind and slurp it with giant biostraws, all that with a fleet of billion of units and over a hundred days.
It is said that the Astronomican is a beacon that attracts them, but since its range is limited, it's hard to tell if there are more Tranids elsewhere.

So, Tyranids act like Army Ants, and don't stick around after striping an area of food. That means that if they would not leave anyone in galaxies they have fed in, and that they are looking for food because they are starving.
http://en.wikipedia.org/wiki/Army_ant

It seems relevant to figuring out Tyranid numbers since it would actually be counter productive for their numbers to exceed a certain size, and the swarms would be the entire colony/hive.

So, Tyranids act like Army Ants, and don't stick around after striping an area of food.

Basically, yes.

For maximum numbers, start here:
http://www.starfleetjedi.net/forum/view ... f=5&t=2067

For numbers of ships and number of specimen, size of a fleet and devastation process, see here:
http://www.starfleetjedi.net/forum/view ... =12&t=1282

PS: I confused ship count with creature count in my former post; somehow both are not considered exactly the same, probably on the sole basis that some are capable of space travel and all other specimen aren't.