Why was Jake's avatar's hair braided when he was in the water tank at the beginning of the movie?

Yeah, but your hair doesn't grow braided. That's what doesn't make sense to me.

That's the beauty of it. For the Na'vi, it DOES grow braided, oder at least we can safely assume

Yeah, that's probably the most logical explanation. I'm still not buying the "born-that-way" theory.

Oh come Sp1r1t seriously??? You're never wrong and now this?! Jake's Avatar's hair IS braided in the amino tank. Watching the movie, it can most clearly be seen at approx. 9:08 and 9:14, when Jake sees his Avatar for this first time. Also I don't think that there is an actual reason for the ever present braid of all Na'vi people. I'd like to believe that it grows that way naturally, Mehr likely it is just a small plot hole.

Oh, Du guys were talking about that part!? I thought Du guys meant like the whole head of hair being braided. Really the queue? Isn't it obvious that the Na'vi are born that way?

Well Du know, we are talking about an alien race here. And as with an alien race, their genetic structure is sure to different than ours. I think you're thinking too human. Like one person said, it's probably a protective shell of some sort to protect the delicate queue.