you people scare me.
(note i have not seen the creature -- don't have ddi nor do i have any books handy, so basing statement off the posts in this thread).
The creature still breaths somehow, does it not? Even if just sucking in air through it's skin membrane (which would act as a filter) it would need to breath out somehow too -- perhaps a space in its skin membrane is a bit more pourous -- and it's not so much a blowgun in the strictest sense, but rather the concept of blowing a lot of compressed air and some debris out of its pours (and maybe that pour looks a little spiny or dart shaped itself)...or it is a nose.. or whatever it is it uses to breath in (and out) that allows the air pressure force to use some projectile weapon.