The Body bias encompasses a great many biological functions, from a bumblebee's bizarre method of flight (which consists entirely of dynamic stall - go look it up, it's really fascinating) to a scorpion's venom, and how sharks swim.
So what I'm wondering is, is there a way to develop a Bod-biased ability for which your race does not normally have the parts? Can you force yourself to grow wings, a little at a time? Or develop a poisonous bite akin to a cobra if you don't normally produce venom? Or are these things completely off-limits without some major surgical or magical modifications?
And if you DO get those modifications - if, for instance, I use magic to graft the venom-sac of, say, a Lernaean hydra onto myself - do you start out with something like 1@1 Produce Venom Bod whatever-the-bias-is-for-that? Or do you get whatever the Lernaean hydra's SAL at producing venom is, seeing as it's almost strictly a function of developing the organ you've just inherited?
Flight looks like an 8 level bod skill.
Symbiont, which would be your grafting venom sacs (I think) is bod level 14.
You ever have Deja Vu? I could have sworn I've done this before.
Grafting on the venom sacs isn't a case of symbiosis; rather, it's a magical method of making it possible for the character to learn a B7@7 Special Attack Form skill he would not otherwise have access to. He would not start out with skill in using or producing his venom unless the magic specifically granted such skill; instead, he would have the opportunity to make a skill learning roll.
Forcing yourself to grow wings sounds like a Psi shapechange skill. Again, this allows the possibility of a skill learning roll.
To sum up, the Bod bias area is not like the others, where you can set out to learn a skill from scratch and succeed if the dice are favorable. It has a unique requirement that you must possess the appropriate body for the skill in question. If you do not, you may not learn the skill until you use some other skill - be it tech, magic, psionic, or bod - to change your body appropriately.
Again Scott provides the correct and concise answer, and I extend my thanks.
Having the venom production sacs and knowing how to use them are distinct abilities, and since the one that matters is the attack, that is the skill I would track. I would assume that venom production follows the attack use skill. And that means your skill at producing and using the venom is dependent on learning the strike skill.
You would probably also want to develop some sort of resistance or immunity to poison, as the chance that you would poison yourself on a botch would seem to be pretty high.
--M. J. Young