Life only needs a very few things to evolve… an energy source, and enough free movement for elements to combine in a chemical soup. Both of those things can exist in the vacuum of space just as easily as on a planet, and people generally underestimate just how much less extreme of conditions exist in vacuum than do at the bottom of our ocean – similar extreme temperatures and lack of food, but actually far less of a pressure differential compared to what we think of for complex life. Looked at that way, it is quite possible for life to evolve in space… especially if Panspermia is correct and the building-blocks of life are already floating through space and recombining in the free-floating vacuum of space. It would start as single celled organisms feeding on solar radiation as an energy source, doubtless, but wherever there are lifeforms using solar energy to stay alive, life will evolve that tries to steal that energy by preying on them.
Given enough time and density, it IS possible for complex, multicellular life to evolve in space… but it is far more likely that life capable of surviving in space will escape from a planet and find an ecological niche for itself in space… or that a creature would be designed by an intelligent agent that could do so. For example, we know that Earth bacteria IS currently surviving in space on many of our satellites, despite our best efforts to maintain a sterile environment… there is enough energy up there for them to thrive.
The space around the Dark Star is EXTREMELY nutrient-rich for an area of space, full of excretions from the odd whale-things and filled with the proteins and amino acids being produced around the Dark Star that seem to be the source of life in this region of the galaxy. It is entirely possible that quite a few life forms have evolved naturally in the void here… but where did the whales come from?
John Drake's Stories 