Editing Xenomorph (section)

===Life cycle===
Aliens are [[eusocial]] life-forms with a [[Caste (biology)|caste]] system ruled over by a queen.<ref name="A2"/><ref name="AvP"/><ref name="A4"/> Their life cycle comprises several distinct stages: they begin their lives as an egg, which hatches a [[parasitoid]] larval form known as a facehugger, which then attaches itself to a living [[Host (biology)|host]] by, as its name suggests, latching onto its face. In the ''[[Alien 3]]'' novelization, Ripley commented that this parasitoid would probably be able to use any host from as small as a [[cat]] to as large as an [[Asian elephant]].

The facehugger then "impregnates" the host with an [[embryo]], known as a "chestburster".{{efn|The terms ''facehugger'' and ''chestburster'' date at least as far back as ''The Book of Alien'' and ''HR Giger's Alien''—behind-the-scenes scrapbooks composed the year of the original film's release—and are used frequently by the film's cast and crew in retrospect.}} During this time, the host is kept in an unconscious state with normal vital functions. After depositing the embryo inside the host, the facehugger dies and releases its hold on its victim's face and head, as shown in ''Alien'' and ''Aliens''. The host will then experience a short period of near-symptomless recovery during which the embryo is in [[gestation]], followed by the sudden and painful eruption of the chestburster from the host's chest, resulting in their death. The chestburster then matures to an adult phase, shedding its skin and replacing its cells with [[polarization (waves)|polarized]] [[silicon]]. 

Due to [[horizontal gene transfer]] during the gestation period, the alien also takes on some of the basic physical attributes of the host from which it was born (something noticed by Ripley in ''Alien 3'', when the xenomorph plaguing the complex [[Quadrupedalism|moved on four limbs]], having gestated within a quadruped (a dog in the theatrical release and an ox in the [[director's cut]]) whereas all the others she had previously seen had gestated within humans/[[Bipedalism|bipeds]]), allowing the individual alien to adapt to the host's environment (breathe the air, etc.). This is also shown in the two live-action crossover films, ''[[Alien vs. Predator (film)|Alien vs. Predator]]'' (2004) and ''[[Aliens vs. Predator: Requiem]]'' (2007), where an embryo, having gestated within a Predator/Yautja, displayed Predator/Yautja physical traits (arthropod-like [[mandible]]s) from eruption onwards.

This process of horizontal gene transfer is also shown to be two-way; in ''[[Alien Resurrection]]'' (film and novelization), Ripley's clone, Ripley-8, is shown exhibiting numerous xenomorph characteristics, physical and behavioural; this is touched more upon in the novelization (chapter 4), where it is described that when a host is infested with an xenomorph embryo, it does not just infest the host like a parasite, but also like a virus, "a major breakthrough in adaptive evolution ... a way to guarantee that any host, any host at all, would provide whatever it was the developing embryo needed, even if/when the host's body was inadequate."

The adult phase of the alien is known by various different names. The adult aliens have been referred to as "drones", "warriors", "workers", and sometimes "soldiers", similar to the way [[ant]]s have been defined. The names of the adult phase have also been used to name different types of adult phases of the alien in numerous sources, including video games, comic books, novels, and the films, but only in the commentaries by the team who created the films. No official name has been given to the adult stage of the alien in the films themselves.

====Queen====
[[File:Alien (1986) - Alien queen.jpg|thumb|Ripley and Newt encounter a queen in ''Aliens''.]]
Queen aliens are significantly larger and stronger than the normal adults, being approximately {{convert|4.5|m}} tall.<ref>[http://www.sideshowtoy.com/cgi-bin/category.cgi?category=082504alien2 Sideshowtoy]. Retrieved February 15, 2006.</ref> Their body structure also differs, having two pairs of arms, one large and one small. The queen's head is larger than those of other adult Aliens and is protected by a large, flat crest, like a crown, which varies from queen to queen. Unlike other aliens, the queen's external mouth is separately segmented from the rest of her head, allowing her to turn her mouth left and right almost to the point where it is facing perpendicular to the direction of the rest of her head. In the second film, ''Aliens'', unlike other adults and queens, the queen had high-heel protrusions from her feet.

Egg-laying Alien queens possess an immense [[ovipositor]] attached to their lower torso, similar to a queen termite's. Like [[hymenoptera|some]] insect [[Queen (bee)|queens]], there appears to be no need for an Alien queen's eggs to be fertilized.<ref name="AvP"/><ref name="A4"/> When attached to her ovipositor, the queen is supported by a "biomechanical [[throne]]"<ref>James Cameron, ''Alien Evolution: Aliens''</ref> that consists of a lattice of struts resembling massive insect legs.

In the original cut of ''Alien'', the Alien possessed a complete lifecycle, with the still-living bodies of its victims converted into eggs. However, the scene showing the crew converted into eggs was cut for reasons of pacing, leaving the ultimate origin of the eggs obscure. This allowed ''Aliens'' director [[James Cameron]] to introduce a concept he had initially conceived for a spec script called ''Mother'',<ref name="mother">''[[Aliens (film)|Aliens]]'', film commentary, ''Alien Quadrilogy'' box set</ref> a massive mother Alien queen which laid eggs and formed the basis for the Aliens' life cycle. Cameron conceived the queen as a monstrous analogue to Ripley's own maternal role in the film.<ref name="mother"/> In that vein, some critics have compared it to [[Grendel's mother]].<ref>[http://web.nwe.ufl.edu/~jchapman/beowulf/beomain.html ''The Alien Trilogy: A New Beowulf''] {{webarchive |url=https://web.archive.org/web/20080209102624/http://web.nwe.ufl.edu/~jchapman/beowulf/beomain.html |date=February 9, 2008 }}</ref><ref>[http://web.nwe.ufl.edu/~jchapman/beowulf/queenA.html ''Alien Queen'' in Cameron's ''Aliens'' (1986).] {{webarchive |url=https://web.archive.org/web/20080115222308/http://web.nwe.ufl.edu/~jchapman/beowulf/queenA.html |date=January 15, 2008 }}</ref>

The queen was designed by Cameron in collaboration with special effects artist [[Stan Winston]], based upon an initial painting Cameron had done at the start of the project. The Winston Studio created a test foamcore queen before constructing the full hydraulic [[puppet]] which was used for most of the scenes involving the large Alien. Two people were inside working the twin sets of arms, and puppeteers off-screen worked its jaws and head. Although at the end of the film, the queen was presented full-body fighting the power-loader, the audience never sees the legs of the queen, save those of the small-scale puppet that appears only briefly. In ''Aliens'', Cameron used very selective camera-angles on the queen, using the '[[wikt:less is more|less is more]]' style of photography. Subsequently, the movie won an [[Academy Award for Visual Effects|Oscar for Visual Effects]]. An adult queen was to reappear in ''Alien Resurrection''. The original mechanical head previously used in ''Aliens'' was provided by [[Bob Burns III|Bob Burns]] and was an altered design. It was repainted with a blend of green and brown, giving it a shimmering, insect-like quality. This color concept would be abandoned in ''[[Alien vs. Predator (film)|Alien vs. Predator]]'' in favour of the original black color scheme.<ref name="AVPmaking"/>

In the climax of ''Alien vs. Predator'', the queen's basic design was altered to make her more "streamlined" in appearance and her overall size was increased to six meters (20 feet) tall. Other changes include the removal of the "high-heel" protrusions on her legs, including additional spines on her head and making her waist thinner because there was no need for puppeteers inside her chest. The [[animatronic]] queen had 47 points of hydraulic motion.<ref name="AVPmaking"/>

''Aliens vs. Predator: Requiem'' (2007) introduced a younger form of the full-grown queen, albeit with traits inherited from its [[Predator (alien)|Predator]] host. Recalling the facehugger's method of embryo implantation, the Predalien uses its inner mouth to directly deposit multiple chestburster embryos into pregnant female hosts, also using its mandibles to latch on the faces of said hosts, completely bypassing the need for facehuggers.<ref name="belly">"The bellybursters were actually in the first draft that Colin and I read...They had the bellybursters...caused by an alien warrior...We actually made it the Predalien that was reproducing in this fashion" –Greg Strause, "AvP-R: Preparing for War: Development and Production" featurette, from the ''Aliens vs. Predator: Requiem'' Region 1 Extreme Unrated Set DVD</ref> This is explained by the Brothers Strause as a means of quickly building an army of Aliens before the young queen evolves into its sedentary, egg-laying state.<ref name="autogenerated1">''"Basically the Predalien's kind of a baby queen—there's a phase in between warrior alien and full-blown queen...they do this thing with embryo implantation.. the idea with that was, how does a baby queen quickly form her own little mini-drone army to get the hive built before she evolves into the final state where she can't completely defend herself?"''--Colin Strause, "AvP-R: Preparing for War: Development and Production" featurette, from the ''Aliens vs. Predator: Requiem'' Region 1 Extreme Unrated Set DVD</ref>

====Egg====
Adult xenomorphs are capable of creating their own reproductive egg ('ovamorph') by [[Pupa#Cocoon|embedd]]ing their prey into an organic substance that (in theory) metabolically reacts to merge host-parasite [[DNA|genetic material]]. The entire process is xeno-dominant, resulting in a facehugger. The eggs laid by the queen are ellipsoidal, leathery objects between one-half and one meter (two and three feet) high with a four-lobed opening at the top. The eggs can remain in a stasis mode for years, possibly indefinitely, until nearby movement is detected. As a potential host approaches, the egg's lobes unfold like flower petals, and the parasitic facehugger extracts itself from the egg and attaches itself to the potential host.

Giger initially designed the eggs with a much more obvious vaginal appearance, complete with an "inner and outer vulva".<ref name="littlegiger">[http://www.littlegiger.com/articles/files/Cinefantastique_09_01.pdf H. R. Giger Alien Design by Frederic Albert Levy], p.36</ref> The producers complained that Catholic countries would ban the film if the allusion was too strong, so Giger doubled the lobes to four so that, in his words, "seen from above, they would form the cross that people in Catholic countries are so fond of looking at".<ref name="littlegiger" />

The interior of the original egg was composed of "Nottingham lace" ([[caul fat]]), which is the lining of a cow's stomach. In the first film, the quick shot of the facehugger erupting from the egg was done with sheep's intestine.<ref name="doc" /> Initially, the egg remained totally stationary except for the hydraulic movement of the lobes; however, by ''Alien Resurrection'', the entire egg was made to ripple as it opened. In the Director's Cut of ''Alien'', an additional scene shows still living crew members being cocooned into new eggs, either morphing into a new embryo or acting as a food source for the facehugger inside the egg.{{citation needed|date=June 2019}} According to the novelization for ''Resurrection'', the Egg, in and of itself, could be considered a living organism in its own right.

====Facehugger====
[[File:Alien-The Facehugger.png|thumb|A facehugger attached to Kane in ''Alien'']]
A facehugger is the second stage in the Alien's metamorphosis. It has eight long, finger-like legs, which allow it to crawl rapidly, and a long tail adapted for making great leaps. These particular appendages give it an appearance somewhat comparable to [[Chelicerata|chelicerate]] [[Arthropoda|arthropods]] such as [[arachnid]]s and [[horseshoe crab]]s.

The facehugger is a [[parasitoid]]; its only purpose is to make contact with the host's mouth for the implantation process by gripping its legs around the victim's head and wrapping its tail around the host's neck. Upon making contact, the facehugger administers a cynose-based paralytic to the host in order to render it unconscious and immobile.<ref>Aliens Colonial Marines Tech Manual</ref><ref name=WYreport/> During a successful attachment, the facehugger will insert an [[ovipositor]] down the host's throat while simultaneously implanting an embryo. The host is kept alive, and the creature breathes for the host.<ref name="A1"/> Attempts to remove facehuggers generally prove fatal to the host,<ref name="A2"/> as the parasitoid will respond by tightening its tail around the host's neck, and its acidic blood prevents it from being cut away. In addition, its grip on the host's head is strong enough to tear the host's face off if it is forcibly removed.<ref name="A1"/>

Once the Alien embryo is implanted, the facehugger will remain attached until the implant is secure, which can take anywhere from less than a minute to 16 hours. Once this happens, the parasite detaches, crawls away, and dies.<ref name=WYreport/> The victim awakens with no awareness of the implantation, believing themselves to have been asleep, and appears to have a normal, healthy bodily function.

According to ''AVPR: Science of the Xenomorph'', a behind-the-scenes documentary on ''Aliens vs. Predator: Requiem'', it is theorized that facehuggers may implant a viral agent [[Cannibalization (parts)|that "commands" the host's cells to grow the chestburster]], as opposed to an implanted embryo.<ref>''Aliens vs. Predator: Requiem'' 2-disc ultimate combat edition</ref> This is an alternate explanation to [[horizontal gene transfer]] as to how the resulting xenomorph is able to adopt the characteristics of its host.

Giger's original design for the facehugger was a much larger creature with eyes and a spring-loaded tail. Later, in response to comments from the filmmakers, Giger reduced the creature's size substantially.<ref name="dvd">HR Giger, ''The Beast Within: The Making of Alien'', Alien Quadrilogy Box-set</ref> At first, Giger assumed that the facehugger would wrap around the outside of the astronaut's helmet, but Scott decided that it would have far more impact if the facehugger was revealed once the helmet was removed. Scott and Giger realized that the facehugger should burn through the helmet's faceplate with its acid blood; subsequent redesigns of the space helmet included a far larger faceplate to allow for this.<ref>Giger 52</ref>

[[Dan O'Bannon]] initially conceived the facehugger as somewhat resembling an octopus, possessing tentacles. However, when he received [[H. R. Giger]]'s designs, which substituted finger-like digits for tentacles, he found Giger's design concept to be superior. Since no one was available at the time, O'Bannon decided to design the facehugger prop himself. The technical elements of the musculature and bone were added by [[Ron Cobb]]. Giger's initial design for the smaller facehugger had the fingers facing forward, but O'Bannon's redesign shifted the legs to the side. When the [[foam rubber]] sculpture of the facehugger was produced, O'Bannon asked that it should remain unpainted, believing the rubber, which resembled human skin, was more plausible.<ref>Dan O'Bannon, audio commentary, ''Alien'', from the ''Alien Quadrilogy'' DVD set</ref>

There has been some debate about the sexual appearance of the facehugger, some saying it unmistakably resembles female genitalia.<ref>{{Cite journal |last=Bundtzen |first=Lynda K. |date=1987 |title=Monstrous Mothers: Medusa, Grendel, and Now Alien |url=https://www.jstor.org/stable/1212458 |journal=Film Quarterly |volume=40 |issue=3 |pages=11–17 |doi=10.2307/1212458 |jstor=1212458 |issn=0015-1386|url-access=subscription }}</ref>

In ''[[Aliens (film)|Aliens]]'', the facehuggers were redesigned by [[Stan Winston]] so that they would be capable of movement. Unlike the creatures in the first film, the creatures would take a much more active role in impregnating their victims. When Ripley throws one off her, the facehugger is now capable of scuttling across the floor and leaping at its prey, wrapping its tail around the victim's throat. The facehugger is also shown to be capable of independently surviving outside of its egg. Due to the film's budget, only two fully working facehuggers were built.

In ''Alien 3'', another addition was planned but ultimately dropped, a "super-facehugger" that would carry the embryo of the queen Alien.<ref name="A3org">Alien3: ''Adaptive Organism: Creature Design'', from the Alien Quadrilogy boxset.</ref> This super-facehugger is briefly glimpsed in the Assembly cut of ''Alien 3'' but not identified as such.<ref name="A3org" /><ref>Alien3: Assembly cut</ref> It made a brief appearance in the canonical ''Alien'' book called ''Alien: Sea of Sorrows'', set after the events of ''Alien Resurrection'', about the grandson of Ripley Clone 8, Ellen Ripley's clone.

====Chestburster====
[[File:Alien 1979 Chestburster.png|thumb|left|A chestburster emerging from Kane's chest in ''Alien'']]
<!-- Deleted image removed: [[File:Alien 1986 Chestburster.png|thumb|Aliens 1986 Chestburster<br/>{{ffdc|1=Alien 1986 Chestburster.png|log=2020 July 17}}]] -->
<!-- Deleted image removed: [[File:Alien 1992 Chestburster.png|thumb|Alien³ 1992 Chestburster<br/>{{ffdc|1=Alien 1992 Chestburster.png|log=2020 July 17}}]] -->
After impregnation, facehuggers die and the embryo's host wakes up afterward, showing no considerable outward negative symptoms and a degree of [[amnesia]] regarding events at the time of implantation. Symptoms build acutely after detachment of the facehugger, the most common being sore throat, slight [[nausea]], increased congestion, and moderate to extreme hunger.<ref name="A1"/> In later stages where the [[incubation period]] is extended in preparation of a queen birth, symptoms will include a shortness of breath, exhaustion, and [[hemorrhaging]] (detectable through biological scanners and present in nosebleeds or other seemingly random bleeding incidents), as well as chest pains caused by a lack of space due to the chestburster's presence or even premature attempts to escape the host.

The incubating embryo [[Horizontal gene transfer|takes on some of the host's]] [[DNA]] or [[Phenotypic trait|traits]], such as [[bipedalism]], [[quadrupedalism]],<ref name="A3" /> possessing the [[mandible]]s of a [[Predator (alien)|Predator]],<ref name="AvP-R">{{Cite AV media|people=[[Shane Salerno]] (writer) [[Brothers Strause|Colin and Greg Strause]] (directors)|title=[[Aliens vs. Predator: Requiem]] |medium=DVD |publisher=[[20th Century Fox]] |date=2008}}</ref> and other structural changes that enable adaptation to its new environment. According to Weyland-Yutani medical scientists in ''Aliens: Colonial Marines'', the chestburster will draw nutrients from the host's body in order to develop a placenta as it grows, attaching itself to several major organs in the process. The placenta has cancerous qualities, such that even if the embryo were removed surgically, the placenta would simply cause the affected organs to shut down, resulting in death; the only exceptions to this are from human-xenomorph hybrid hosts like the cloned Ripley 8, who survived an extraction procedure without issue.

Over the course of one to twenty-four hours--indeterminable in some cases, and sometimes up to a week, in the case of some queens--the embryo develops into a chestburster, at which point it emerges, violently and fatally ripping open the chest of the host.

There is no on-screen explanation of the reasons for the different incubation times. Fully-grown aliens may avoid harming species acting as hosts for un-emerged chestbursters, though this may only be in the case of a queen embryo.

When a chestburster erupts from the body of a human host, it is less than {{convert|30|cm|in}} tall, although the embryo can vary in size from a guinea pig to a large dog depending on the size and species of the host. Its appearance and adaptive characteristics are also determined by the host. Typically, its first instinct upon emerging is to flee and hide until full maturation, as well as find a source of nutrition. However, it soon undergoes a dramatic growth spurt, reaching adult size in a matter of hours; in ''Alien'', the chestburster had grown to {{convert|2|m|ft}} in height by the time the ''Nostromo'' crew located it again.{{efn|In ''Aliens'', Ripley claims that the creature killed the entire crew in 24 hours, so the growth stage must be under one day}} The chestburster is shown to have molted before reaching maturity.<ref name="A1"/> In ''Aliens vs. Predator: Requiem'', Alien warriors who are still growing are shown, displaying shed skin. In the unrated cut, the [[#Predalien|Predalien]] is shown wiping off its final molted skin at the film's start.

The chestburster was designed by ''[[Alien (film)|Alien]]'' director [[Ridley Scott]] and constructed by special effects artist [[Roger Dicken]].<ref name="woman">{{cite book |last1=Gallardo |first1=Ximena |date=2006 |title=Alien Woman: the Making of Lt Ellen Ripley |pages=25 |publisher=A&C Black |isbn=9780826415707 |url=https://books.google.com/books?id=4ecFu4B_CpoC&dq=chestburster+roger+dicken&pg=PA25}}</ref> Giger had produced a model of a chestburster that resembled a "degenerate plucked turkey"<ref>Giger p. 56</ref> and was far too large to fit inside a ribcage. Much to Giger's dismay, his model reduced the production team to fits of laughter on sight. Scott drafted a series of alternative designs for the chestburster based on the philosophy of working "back [from the adult] to the child" and ultimately produced "something phallic".<ref name="burster">''Alien Evolution'', in the [[Alien Quadrilogy]] box set</ref> The chestburster in the original ''Alien'' was armless, but arms were added in ''Aliens'' to facilitate the creature crawling its way out of its host's corpse.<ref name="Winston">{{cite book|author=Jody Duncan|author2=James Cameron|name-list-style=amp|title=The Winston Effect: The Art and History of Stan Winston Studio|date=2007|page=336|isbn=978-1-84576-150-9|publisher=Titan|location=London}}</ref> This concept would be abandoned in ''Alien Resurrection'', but it would return in ''Alien: Covenant''.