A space-dwelling lifeform is a spaceborne species native to the Delta Quadrant. They propel themselves through space via flagellation much like protozoa and are capable of approaching speeds up to 3,000 kilometers per second.
Space-dwelling lifeforms travel in lightly dense swarms consisting of fewer than two thousand organisms. Among them is at least one dominant organism, physiologically similar to the others but much larger. This larger lifeform attracts mates by emitting a stream of plasma, causing the smaller lifeforms to attach themselves to the larger lifeform. In the process, the smaller lifeforms roll over and change their color from a dark red to a bright blue to indicate submissiveness.
The larger lifeforms also use their ability to emit plasma as an aggressive tactic, particularly towards a sexual rival.
These lifeforms do not appear to have a digestive system; instead, they have an extremely porous outer covering which they use to absorb particle directly from space. In addition, they are capable of generating their own magnetic wake.
USS Voyager encountered a swarm of space-dwelling lifeforms in 2371. While observing the creatures, the starship was pulled into the swarm by its magnetic wake. Aboard Voyager, the electrophoretic levels created by the swarm caused Kes' metabolic activity to increase. As a result, the young Ocampa entered a premature elogium.
During Voyager's attempts to escape the swarm, the smaller lifeforms became sexually attracted to the starship and began attaching themselves to its hull. This was due to the fact that the vessel's subspace signature matched the plasma stream emitted by the larger, dominant lifeforms. Sensing a rivalry, one of the dominant lifeforms attacked Voyager. Determining the creatures' behaviors, the Voyager crew had the ship roll over and vent plasma residue to make the ship appear blue, signaling its submissiveness to the dominant creature. Voyager was then able to leave the swarm and continue on its journey towards the Alpha Quadrant. (VOY: "Elogium")