On Writing Alien Species

One of the most fun aspects of writing for me is creating new alien species.
It's one of the handful of times during my writing process that I actually get to use my biology major (and feel like all of those years spent paying for college weren't totally in vain).

I'm not sure how other people do it, but for me I like to hunt up the strangest animals the Earth has produced, and then think about how I can take something neat about them to incorporate into a new alien being.  Sometimes focusing on one aspect of a real creature can lead to the creation of a whole species and culture.

For example, I think about methanogens- that's microscopic organisms that can live in and around volcanoes.  They have something called di-sulfide bridges in their DNA which prevents it from flying apart under extreme temperatures.  I think about that and then start scribbling down notes (I have to use pen and paper for this, just a quirk of mine):

-High heat tolerance
-Volcanic planet origin?  Volcanic region of a planet?
-Body form would reflect a land evolved animal (3 jointed limbs for running or climbing, would probably have a snout or muzzle of some kind...)
-Food around volcanoes would be microscopic organisms on or in the rock like lichen, oh wait, there are oases around Hawaiian volcanoes... species could be tree-evolved after all (like us)... etc.

And so on.  I tend to follow the principle that society and culture follow from body form for creating a species' psychology, philosophy, and other non-physical aspects.  Do brutal surroundings create a brutal species or one that is highly tolerant of adversity?

Sometimes it helps to look up human groups that live in similar environments and take aspects of their cultures to incorporate into the new alien one.

No mater what I do, though, I like to have one hard rule:  Be as realistic as possible.

Realistic you ask?  How can I be realistic when dreaming up things that never were?

By realistic I mean being creative without violating any of the rules by which our universe operates -mostly.  Every now and then I like to throw in something that we think of as impossible just for fun.  However, I make this the exception rather than the rule.  I want my readers to be fully engaged in the story as I like to be in creating it.  Anything that would throw them out of that and make them think, "ugh, that's just dumb" is an anathema to me.

I put a lot of research into my work to make the odds of that happening as small as possible.  That is part of the fun of writing science fiction.  I get to read about a bunch of different fields like astronomy, anthropology, and chemistry.  I know it might sound a bit boastful, but science fiction is one of the few genres that gets to draw on the sum total of human knowledge.

To me, that's just the coolest and most fun thing about it, and I guess that's why I enjoy writing it so much.