How does a Xenomorph mature into its adult form?

Nice theory!

GAVIN SINGLETON - What an incredibly intricate hypothesis! I happen to believe there is a significant amount of weight behind this presentation! Thank you ever so much for taking the time to create this and share it with us! :)

i use to think that the chest burster developed a hard outer shell around it making the dome head where it would crawl around like a beetle before developing the rest of the body the chest burster becomes the inner jaws and the primary jaw develops a stupid theory i use to have when i was ten XD

The Aliens RPG says chestbursters eat (anything really- organic or inorganic) to reach full size.  Which recalls the deleted food locker scene from Alien.  After reaching full size they only eat to heal or generate webbing.

Veronica Cartwright has mentioned that it went from white to black as it matured because it was bruising from growing so quickly.

The simplest idea is that they have an incredibly enhanced metabolism that kicks in when they're still an embryo, and stops when they reach 7-8 feet in height.

The gestation and growth times vary wildly.  Kane was in the ballpark of 16 hours for gestation and less than two hours to reach full size.  The Fiorina creature however, emerged more developed, but was still only adolescent size when it killed Murphy over 10 hours later.  It's gestation was closer to Kane's however (around 15 hours).

Dialogue about rapid growth of the Auriga creatures was deleted (probably not even shot).  AvP went to a ridiculous extreme of gestation and growth in under 10 minutes (but that could be explained away by the Predators mucking about with the Queen).  The Gunnison creatures spawned by the crash had a more normal gestation - around 8 hours.

very cool post about the cycle theory! I hope we get to see something resembling the xenomorph's growth cycle with these mutations in Alien Covenant

Adding on to the cocoon theory, maybe those tubes on a Xenomorph's back are what releases the resin?

I doubt they coccoon themselves to grow.  It would make them vulnerable.  Plus we see the 'mid-stage' in Alien3 when the Alien kills Murphy.  But that creature didn't have the dorsal tubes.

Very interesting topic indeed. The rapid growth definitely would be a painful endeavor and usually, growth like that results in a shortened life span and malfunctioning limbs and joints. Yet, the Alien seems fine when it's fully mature.

I really like the mention of the Alien being white but turning black due to extreme bruising - nasty!

My theory is more inline with what S.M mentioned - in order to produce energy and fuel a metabolism, you need fuel. For us, it's calories. The Alien clearly requires the same nutrients we ingest or the Facehugger to Chestburster process would be a waste and Aliens could simply just "grow on trees" (Covenant reference...).

With that understood, it's safe to assume that the Alien does require food, or some form of caloric intake to fuel it's insanely fast metabolism. I also feel like they shed multiple layers and multiple exoskeletons as they grow. 

It's interesting to note however, in the AvP RTS game Aliens vs. Predator Extinction, the Aliens DID cocoon prior to emerging fully grown. So.. it is still a possibility and we could simply have not seen it yet.

Something that challenges the need for food to reach full size is that there's no evidence the Aliens ate on the Auriga.  There's no obvious remnants or remains of food in the cages.

In fact apart from AvP:R, and some questionable scenes in Alien 3, there's no evidence they eat at all.

But where would they get the energy from?! If they used sunlight and converted it to energy the way plants do, okay, but Aliens come out at night and rarely are ever seen moving about in the light. 

If they don't eat then they must have some truly "Alien" method for producing energy to grow and move around. 

"But where would they get the energy from?! "

That's the million dollar question.

The old RPG also mentions they can access solar energy, static electricity and direct current.  The energy generated by a light breeze is sufficient to sustain an adult.

It could simply be that they're efficient enough to grow to full size on whatever was gained from the host.

Electric current I could buy, even solar energy despite them being primarily nocturnal. But air? That would require some explanation haha.

But what would cause the Aliens to lay dormant? It seemed as though until the Queen signalled them to attack or hosts walked near them that they remained relatively lifeless. 

I think they were getting at kinetic energy from a breeze is enough to keep them 'charged'.

As for why they were dormant - conservation I would assume.  They guess there's no more hosts, so they'll just sit and wait until more show up.

I remember an old theory that Xenomorph Chestbursters eat any material they can get their two jaws on to use to fuel their growth, be it a cat (ala the AVP2 video game), or simple metal and other miscellaneous material.

It would certainly explain how they manage to get the physical material required for growth, and would add an element of mystery as to why a creature would have such a resource-efficient growth process in the first place.

Time for me to chip back in on this one, me thinks.

As S.M. mentions there is next to no evidence in the movies that shows that the Xenomorph eats before transforming from a Chestburster into an Adult. One suggestion could be some form of hyper-accelerated metabolism, but remember that the Xenomorphs that took over Hadley's Hope could not be seen by the Marines infra-red visor - I know some will argue that the creature probably produced heat equivalent to that of the ambient temperature of the hive, which Huson called a "Dry Heat", but if the Xenomorph does emit such heat wouldn't such heat have alerted Ripley to the Aliens presence when it hid aboard the Narcissus escape shuttle.

While there is no evidence to support my theory, I like to think that the answers stem from a reservoir of the notorious Black Goo from Prometheus, stored somewhere within the Xenomorphs biology. When transforming into and adult a Chestburster sheds its silicon skin, revealing its exoskeletal frame and "sweats" the black goo, causing the maturation process. When fully grown the Adult Xenomorph then uses the gases and heat emitted from the Black Goo's viral cells reproducing within its "bowels" to fuel its heightened mobility as well as its accelerated healing. It may also be possible that the Xenomorph uses this internal reservoir to transform a host into an egg, and that the Queen may use the reservoir to fuel her endless productions of eggs. But thats just my theory.

Though, the more I think on it, my theory could explain the importance of the Black Goo in Prometheus and its "DNA" to Alien/Aliens? Hmmm...

Interesting Topic i missed.... when i am less busy i hope to add my two cents... but its something pretty much been mentioned already on here.

Upvoted!