movement of space animals
Animals on planets are so 20th century - let's herd us some space animals!
In this story I have the need to move a herd of pesky space animals. They like Suns for their juicy solar energy and hydrogen, have stumbled into our solar system and are in no hurry to leave.
This causes some problems, I'll come up with those later on, the point is that my guys will want to move the herd about.
So:
* How would an animal in space evolve with an ability to move rapidly? What, specifically, would be the bodily apparatus for movement?
* How would we go about herding them?
* They move at about an eighth to a half of the speed of light, can be a bit less or a bit more (I'll change this if it turns out to be problematic, please let me know. Do mind that they have a long way to go between solar systems).
* The movement must be sustained for quite a long time (dozens of years, between stars), so particle ejection (Jet?) based movement is less preferable to say, some form of gravity manipulation, because I don't want my space animals to get stranded in the great void with an empty particle/fuel tank, without the ability to refill it.
* They're solid animals, not gas/plasma based like in some sci-fi stories
* Their size has to be larger than a small space craft (can't nudge them about, or capture them easily)
* They're not aggressive but will defend themselves if they feel threatened
* I don't care much about shape, though exotic ones will be nicer for the story (see: http://worldbuilding.stackexchange.com/questions/1359/how-do-i-prevent-my-turtle-from-collapsing-under-its-own-gravity/2746#2746 )
* EDIT2: The life span of the animals and their evolution span can be long, really long. I'm thinking a couple of thousand of years for life, and the evolution can take billions of years. 162
But you may suggest other spans as needed.
EDIT: Ok, I found this: http://worldbuilding.stackexchange.com/questions/1401/could-life-form-in-outer-space but I don't feel that it covers the speed and supposed energy requirement of my space critters. Also, it seems to lack a hard science discussion about evolution (see the comments by <PERSON>). I'd like to get a plausible, sizeable, rapid-moving animal that will eventually damage the sun or humanity's requirements of the sun (it's a futuristic thing so we might have a <PERSON> sphere that could be ruined or something like that. Suggestions into the manner of the disruption that the animal will cause are welcome, especially if they have to do with the animal's requirements for movement).
<PERSON>, space cowboys 162