Board Thread:Warhammer 40k General Discussion/@comment-46.162.84.254-20130704080553/@comment-24821739-20140709223033

Tyranids can go long times without needing sustenance.

This is not said anywhere (in cannon), but, the Narvhal causes the Tyranids to travel slower than Warp-Capable races. In between galaxies is dead space... Thus, they would have to either shut down their metabolism, or find another way to survive in deep space, as there is no bio-mass to devour (via stores of biomass or something). (This could be a completely idiotic thing to say, however, that's my understanding. I'm no astrophysicist but I found this!)