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"In a few hours it's gonna burst through your ribcage, and you're gonna die. Any questions?"
Ripley 8, to Larry Purvis regarding the Chestburster (from Alien Resurrection)
Alien-The Chestburster
A Chestburster from Alien.
Biological information

Potentially any planet

Physical description



20 lbs

Skin color



Rapid growth rate, appearance varies depending on host

Other information



The Chestburster (variously: Chest Burster,[1] Chest-Burster[1] or chestbuster[2]) is the infant form of the species Xenomorph XX121 and the third stage in its life cycle. It is most well known for its horrific method of gestation — as an embryo it is implanted into a host lifeform's chest cavity by a Facehugger, and upon maturing it will erupt violently from the host's chest, killing them in an incredibly bloody and traumatic fashion. Chestbursters are small, generally not more than a foot tall and around two feet long including their tails, although larger examples have been seen.[3]


Chestbursters resemble large worms, beige or brown in color and with a mouth of metallic teeth and a tail capable of propelling the creature at considerable speed. Some Chestbursters have been seen to possess arms,[4] but this is not always the case, with others merely having small stubs where presumably the arms will eventually develop. It is possible a longer gestation period may determine the presence of arms at birth; notably, Queen Chestbursters (which have a considerably longer gestation period) have been known to birth with all four of their arms present, as well as legs and a partially developed head crest.[5] Even regular Chestbursters have been known to birth fully formed, with arms and legs, essentially just a smaller version of the adult that it subsequently developed into.[6] The reason for this is unclear, although it has been theorized that, in cases where a Chestburster is unable to escape its host's body at the usual time (perhaps due to greater structural integrity of the host's ribcage and chest cavity), the host may die prematurely as a result of the invasive organism within them, which will subsequently develop further until it is large and strong enough to emerge.[3]

During development, the Chestburster is attached to the host via a small umbilical cord, through which it presumably gathers the nutrients it needs to grow.[7] Owing to the Xenomorph's tendency to assimilate a degree of its host's genetic traits via the DNA Reflex,[8] Chestbursters will also vary widely depending on the lifeform in which they gestate. For example, Xenomorphs born from Yautja will feature the mandibles of their host at birth.


A Chestburster is generally introduced into its host by a Facehugger, although at least one Predalien — a juvenile Queen — has been known to insert infant Xenomorphs directly into a host without the need for a Facehugger.[9] While the terms "impregnation" and "implantation" are liberally used to describe this process, they are not strictly accurate; studies by Lasalle Bionational have shown that no actual embryo is inserted into the host. Instead, the infant Xenomorph begins its life as a knot of specifically tailored cancers that bring about chemogenetic restructuring of the host's cells, essentially "building" the Chestburster from the host's own biological material at a cellular level.[10]

This complex process involves the absorption of organic material from the host, which is then broken down at a molecular level and rearranged into new compounds. Carbon units are disassociated and recombined into crystal lattices, which are used in the formation of the Xenomorph's hard body structures.[11] Freed H+ ions are combined with surplus sulphate (SO42-) and nitrate (NO3-) groups to form the basis of the creature's highly acidic blood.[11] As a side-effect of this unique process of development, Xenomorph genetic material is passed to the host as well as vice versa, and it is this trait that presumably allowed the scientists aboard the USM Auriga to clone the Queen gestating inside of Ripley 8 as well as Ripely 8 herself.

The manner in which the Chestburster develops from the host's genetic material means that the host's characteristics will in turn dictate, to an extent, the Xenomorph's physical features — embryos are thought to copy 10-15% of the host's genetic code in a process dubbed the "DNA Reflex".[8] This genetic absorption is designed to help Xenomorphs adapt to the environment in which they are born, and also helps the developing creature to "hide" from the host organism's immune system.[12] The assimilation of host DNA leads to physical (and possibly mental) variations in the adult creature. The Predalien Chestburster, for example, sports the signature mandibles of the Yautja (and grows dreadlocks upon reaching maturity), while quadrupedal hosts produce quadrupedal Xenomorphs. It is also theorized that the intelligence and instincts of the adult creature may be influenced by the host.[13]

During the formation and growth process, the host initially exhibits no considerable outward negative symptoms, although symptoms build acutely after detachment of the Facehugger, the most common being a sore throat, slight nausea, increased congestion and moderate to extreme hunger.[14] During the extended gestation period of an embryonic Queen, symptoms may additionally include a shortness of breath, exhaustion and internal hemorrhaging (detectable through biological scanners and present in nosebleeds or other seemingly random bleeding incidents), as well as chest pains inflicted either by the lack of chest space due to the Chestburster's presence, or even premature attempts to escape the host.[6]

Growth of the Chestburster is rapid; the creature's signature inner jaw is known to form within an hour of implantation.[12] However, certain physical defects in the host are known to adversely affect Chestburster development. For example, Larry Purvis, one of the civilians impregnated by science team aboard the USM Auriga, suffered from a thyroid deficiency which dramatically slowed the growth rate of the embryo inside him.[15] As a result, birth did not take place until several hours after would normally be expected.


When fully developed, the Chestburster releases enzymes that soften the bone and surrounding tissues of the host's chest cavity to facilitate its egress,[16] before finally forcing its way through the sternum. While the host may experience some discomfort in the minutes and hours leading up to the event, including mild chest pain and nausea, the actual birth itself is rapid, with the Chestburster exiting within seconds of the onset of severe pain upon the host.[14] The process begins with cramp-like pains in the victim's chest[17] but rapidly progresses to debilitating agony and uncontrollable convulsions. When the Chestburster finally emerges it induces severe shock, organ rupture and massive blood loss; death is almost instantaneous, but excruciatingly painful.

The Chestburster is arguably the most vulnerable stage of the Xenomorph's life cycle. While it grows rapidly, in the early stages the infant is almost defenseless, save for its acidic blood. If born in a populated area a Chestburster will immediately seek escape, preferably via a means that will not allow easy pursuit (e.g. through air ducts or vents, possibly going as far as burning a hole in a wall or floor with its own blood). While they have been known to attack and kill humans even in this infant stage,[18] the Chestburster's proficiency in this regard is limited and the creatures are known to simply prefer hiding until they reach maturity. If undisturbed, newly born Chestbursters may consume parts of the human victim for sustenance.

The extreme psychological impact of the Chestburster's birth mechanism has actually been known to have an adverse effect on the survival of other embryos — witnesses to the gory spectacle who discover they are impregnated themselves often seek to end their life before enduring such an agonizing end, whether through their own actions or assisted suicide. This can be fatal for the Chestburster, although depending on the manner of death it is possible for it to survive even after the host has died and emerge later.[3] Stasis is known to halt Chestburster development and prevent birth, as seen when Corporal Tequila was placed into hypersleep to prevent the embryo inside her from hatching.[19]

Few materials seem to be immune to a Chestburster emergence; Chestbursters have been known to burst through Colonial Marine body armor (as seen in Private Clarison's case). It is unknown whether the Chestburster employs measures such as its acidic blood for this purpose, or whether it is its sheer strength that allows it to punch through tough material.


After birth, Chestbursters grow incredibly rapidly — the Alien aboard the Nostromo reached adulthood mere hours after being born.[14] Aboard the USM Auriga, scientists noted that Chestburster development was even perceptible with the naked eye.[20] USM scientist Dr. Carlyn Williamson also noted that captive Chestbursters on the Auriga expelled a "dark, viscid foam" that surrounds their body during growth;[20] whether this foam is for the purpose of concealment or some aid to their growth is not known. Infant Xenomorphs will repeatedly shed their skin like a reptile as it grows, and these skins are often the most visible sign that a Xenomorph is nearby before the creature reaches maturity.[14][6]


While the birthing of a Chestburster is inherently fatal, it has been claimed or proposed on several occasions that removing a Chestburster before it emerges is possible, leaving no long-term residual effects to the host.[6][7][19] However, research has shown this to be inherently futile — the cancerous development process that creates the Chestburster means that, even if the embryo were safely removed from the host, they would soon develop a number of terminal tumours that would cause them to perish in a fairly short period of time.[11][21]

Nevertheless, there is a single case where the removal of a Chestburster has been carried out successfully and the host has survived for many years — that of Ripley 8 aboard the USM Auriga, who made a full recovery after the Cloned Queen embryo was removed from her chest. However, it has been postulated that this her survival was solely as a result of her altered genetic structure. In essence, Ripley 8 was part-Xenomorph and therefore a unique case, and it seems unlikely a normal human would be capable of likewise surviving.

Non-canon DepictionsEdit

Alien 2: On EarthEdit

Main article: Alien 2: On Earth

A Faceburster in Alien 2: On Earth.

In the non-canon film Alien 2: On Earth, the Xenomorph Chestbursters are shown to erupt from the host's face instead of their chest, earning them the colloquial name "Facebursters" among fans. At first glance, the Faceburster resembles the typical Chestburster, but when fully exposed they are considerably longer and more worm-like in proportion and appearance. They are also seen to use their long tails to slice off victims' heads.

While Alien 2: On Earth has nothing to do with the official franchise, the idea of an Alien erupting from someone's face was later used in Alien Resurrection, when a Chestburster emerges from Larry Purvis and bursts through Dr. Wren's head, erupting from his face, as the two struggle. The particular Chestburster responsible has been referred to as the "Faceburster" by the film's crew and fans, although anatomically it is no different from a standard Chestburster.

Behind the ScenesEdit


ALIEN chestburster1280

A production still of the Chestburster scene in Alien.

The entire concept of the Chestburster was intended as the ultimate perversion of joyful birth — the wonder of new life tainted by the horrific death of the person giving birth to it.[22] Intended to be Alien's big shocker moment, the Chestburster was perhaps, next to the physical form of the fully grown Alien, the most important design to be made. The crew acknowledged that, if the Chestbursting scene lacked punch, then the entire film would likely be sunk as the audience may not take further events and dangers seriously.[23] For the infant creature's design, H. R. Giger was pointed towards the art of Francis Bacon by Alien's director, Ridley Scott. Bacon, already a favourite artist of Giger's, served as the inspiration for the first incarnation of the Chestburster. "I think when you want to be really scared," Ridley Scott said to Cinefantastique, "you've got to think about what it is that makes you very physically uneasy, that upsets you in a primal way. And I'm not easily upset, but we looked at various painters' works, and the one that caught us was by Francis Bacon, the three flesh necks with the jaws on the end. The primality, if there is such a word, was what interested me."

"Ridley Scott asked me to do something based on a crucifixion painting by Francis Bacon, in which the only thing of the figure you see is a mouth and some flesh behind. He wanted something like that which could go into the stomach or come out of it. First it was designed as a little dinosaur and I didn't like it at all, but finally we gave him a worm-like shape with no legs... I believe the strongest, scariest feeling is to see an alien-worm inside a person's body moving under his skin."
―H. R. Giger on his initial design concept for the Chestburster.
Normal chest burster

Giger's first abortive attempt at the Chestburster, inspired by Francis Bacon.

Giger's first Chestburster design was received with reservation and ridicule. "To me, it looked like a plucked turkey," said Roger Dicken, "a veined, repulsive-looking thing with fangs... Obviously, you couldn't get something the size of a large turkey out of a human chest, but they were going to cheat it somehow." Despite his incredulity at the design, Dicken crafted a workable prop. "Dicken reproduced it very faithfully," Ridley told Cinefex. "The problem was that what looked great on paper didn't in actuality." Dicken had brought the prop to the studio and operated it like a hand puppet. The effect looked "entirely comical – it looked like some kind of plucked, demented turkey."

Frightened of the Chestburster eliciting laughs rather than screams, Ridley went back to the drawing board. "We went back and re-examined various illustrations and ideas, and tried to come up with something we thought would be the most frightening," he told Cinefantastique. "I wanted more of a biological link between the baby, which is what we were really designing, and what the final creature would look like. And I wanted it to be a very smooth object. The other was all wrinkled and ancient-looking, like some malevolent muppet. And when it came out, I wanted it to look very rude – and totally carnivorous." Giger also worked on another Chestburster design, somewhat similar to the creature finally used in the film, but with more vicious fangs and a misshapen body. However, this was not used, despite support from Dan O'Bannon.[24]

"We worked for weeks on the baby [Chestburster]. I knew I didn't want something with bumps and warts and claws. You know, I find that most horror films have never really frightened me; and I tend not to be convinced by a lot of science-fiction films specifically because of the effects. So I knew it had to be good, this baby. We decided that the big chap, in embryo form, would have a head either tilted down or tilted back. We tilted it back because it seemed more obscene that way, more reptilian, more phallic."
―Ridley Scott on the Chestburster's redesign.

Ultimately, the creature seen on screen was primarily designed by Dicken, with input from Scott.[24] According to Dicken, "The overall look of the Chestburster was this long banana-shaped thing with a head on it from the Giger drawing. I made various models of it. One afternoon, Ridley Scott came over here and over cups of tea we literally constructed the thing by trying on different tails and so on, and it was finally agreed that that was what it would finally look like." The creature originally featured arms, but these were ultimately removed from the final creation.[25]

Alien propEdit

The Chestburster in Alien consisted of a curved metal rod within the body, culminating in a hand grip below to allow the operator to hold the puppet. "About halfway along — up where the neck would have been if it'd had one — was a flexible steel spring, and then the rest of the rod went up into the head area and then down underneath the jaw to give it strength," explained Dicken. "I ran a wire, through a series of eyelets, along the whole length of the rod and then down into a ring which fit around my finger; so when I pulled on the ring, the spring would make the front section bend over."[24] The jaws and arm stubs were also animated, activated by air provided by simple squeeze bulbs, while larger air bladders simulated the Chestburster's breathing and animated the "gills" on the side of the head.[24]

The original ChestburstingEdit

Chestburster BTS

Behind the scenes image of the Chestburster erupting from Kane.

The Chestburster was actually the first stage of the Alien's lifecycle to be filmed for Alien.[24] The creature's birth was shot using an artificial torso filled with blood and viscera, with actor John Hurt's head and arms coming through from underneath the table.[26] The production crew acquired animal innards from a local butcher's shop to dress the prosthetic chest. Bar Hurt, Ridley Scott kept the design of the Chestburster hidden from the cast. While the actors knew that the creature would be bursting out of Hurt, they had not been told that a large amount of fake blood would also be squirting out in every direction from high-pressure pumps and squibs, and their horrified reactions in the film are genuine. The Chestburster was shoved up through the torso by a puppeteer who held it on a stick; initial takes failed because the puppet would not penetrate Hurt's shirt, and so the clothing was thinned with acid and scored with razor blades to weaken it.[26] Producer and co-writer David Giler told Cinefantastique, "The 'Chest Birth' was simulated for the actors by surprising them with a shower of animal entrails. That's why their looks of disgust and horror are so real. They had no idea what we were going to shoot that day."

"I was there, and they had three cameras set up 'cause they wanted to catch it from all angles and all the cameras were covered in clear plastic tarps. The lenses were covered with flat optical class like underwater cameras and Ridley and the D.P. and all of the technicians were all wearing overalls up to their necks. It took them three to four hours to get the actor doing to do the stunt rigged because there was mechanical stuff involved. Meanwhile the other actors didn't come on set, I don't know where they were, they had a room where the actors could hang out and talk to each other. Then they brought them in when they were ready for it, they hadn't seen all the preparation. All they did was they walked on, they saw all these tarps, and they saw huge hydraulic machines with hoses leading to this rigged man, and they saw everybody wearing coveralls. I looked at Sigourney Weaver, who's the lead. I saw her face as she looked at the tarp, coveralls and camera, and she seemed to go a little shaky. The actors looked real uneasy when they saw the set-up because it looked like they were trying to prepare for Vesuvius."
Dan O'Bannon regarding the day of filming.
"I knew that the special effects men were trying to rig the blood so that it would hit me. I was absolutely green. There had been a huge vat of kidneys and livers and intestines floating around on the set for two days and the stench was awful."
Sigourney Weaver.
"I noticed Sigourney really looking scared. I said, 'You're really getting into character.' She said, 'No, I have a feeling I really feel I'm going to be pretty repulsed right now.' A couple years later, I read an interview where she said, 'The reason I knew it was I saw Dan O'Bannon and Ron Shusett over in the corner, and they were putting on rubber raincoats and laughing like little kids on Christmas morning. So I knew it was going to be a blood-bath!' It worked so great. Veronica Cartwright – when the blood hit her in the fact, she totally passed out. I heard from Yaphet Kotto's wife that after that scene he would go to his room every night and not talk to anybody."
Ronald Shusett.
"The amount of blood was just unparalleled. I saw Veronica Cartwright get drenched from head to toe in blood and scream her fool head off and fall backwards over a table and brain herself... Then afterwards these two people pick Veronica Cartwright up and she was weak-kneed and they had to help her off the set. She was drenched, all her clothes sticking to her, and her hair sticking to her with this red dye and she was near hysterics. And twenty minutes later they come back and they had showered her and fixed her up and put a duplicate costume on her and she looked the same, but a little spooked, and I went up to her and I said, 'That was really terrific. Was that all acting?' And she looked at and said in a kind of spooked voice, 'Well, I was a little freaked-out.'""
―Dan O'Bannon.
"John Hurt had been lying there for about four hours while they fixed him up. By the time I got there I was thinking, 'uh oh.' They had three cameras so they could get all our first reactions – our gut reactions. That's what you see in the film. Those reactions are totally raw. Nobody quite anticipate what was going to happen. I was told I'd get some blood on me. I had no idea the hose was pointed at my face. I felt very queasy afterwards.""
―Veronica Cartwright.

After reviewing the footage of the scene, many of the film's crew became concerned that the sequence was simply too graphic and would be rejected by Fox executives. While Fox was indeed nervous about the bloodshed, they eventually allowed the scene to stay.[23] It has since become an iconic moment not just in the film itself, but in cinema in general. Film critic Mark Kermode later summarized, "This compellingly grotesque spectacle has become as shockingly iconic as the head spinning sequence in The Exorcist, or the shower scene in Psycho."[22]

Aliens propEdit

ALIENS Behind-the-Scenes Chestburster FX Test03:18

ALIENS Behind-the-Scenes Chestburster FX Test

Behind the scenes footage of the Chestburster mechanism used in Aliens featuring commentary by Stephen Norrington who built the Chestburster's mechanism.

According to Matt Winston, "No sequel to ALIEN would have been complete without paying homage to the infamous 'Chestburster' scene, so director James Cameron memorably included the grotesque parasites in ALIENS as well."[27]

For Aliens, the design of the Chestburster from the first film remained practically unchanged by the special effects team at Stan Winston's studio, apart from adding two tiny arms to create consistency between the infant creature and the anatomy of the fully-grown Warrior. Cameron and Winston decided that the addition of arms also made sense on a purely functional level, allowing the Chestburster to pull itself free from its victim's chest.[27]

Chestburster BTS Stuff-A2

The lightweight hero chestburster mechanism was capable of fluid movement.[27]

To achieve the effect of the Chestburster emerging from Mary (Barbara Coles), Winston and his crew created two Chestburster puppets. The first was a simple glove puppet, built to be tough enough to rip through Coles' artificial foam latex chest and clothing.[28] The second, "post-burst" puppet was a more delicate animatronic, incorporating cable-controlled mechanisms that allowed a wide-range of fluid movements.[28]


  • The Chestburster scene is said to be the sole reason Dan O'Bannon and Ronald Shusett's script was originally picked up by 20th Century Fox, such was it's perceived impact.[25]
  • The time it takes for a Chestburster to develop and emerge from its victim varies wildly throughout the Alien series. Following the death of the Facehugger attached to Kane in Alien, it takes only a few hours for the embryo inside him to emerge. However, in Alien3 the Chestburster inside Ripley takes several days to develop (although this particular embryo was that of a Queen, and can therefore be assumed to have a longer gestation period, due to it's greater size and complexity). In Alien vs. Predator and Aliens vs. Predator: Requiem, Chestburster development was accelerated rapidly, to the point where the creatures would emerge only 5 to 10 minutes after implantation. In the more recent video games featuring the Xenomorph, a gestation period of several hours is once again typical.
  • Despite being so integral to the Xenomorph's lifecycle, the Chestburster is conspicuously absent from Alien: Isolation. However, the bodies of people who died giving birth to a Chestburster are found on Sevastopol.


See Also Edit

  • Bellybursters — Another embryonic Xenomorph form that differs in its gestation and birth characteristics.


Behind the scenesEdit



  1. 1.0 1.1 Warren Presents the Officially Authorized Magazine of the Movie Alien Collector's Edition
  2. Alien Anthology - Disc 2: Aliens - commentary
  3. 3.0 3.1 3.2 Vincent Ward (writer) and David Fincher (director). Alien3 Assembly Cut [DVD]. 20th Century Fox.
  4. James Cameron (writer and director). Aliens [DVD]. 20th Century Fox.
  5. "Weyland-Yutani Archives - Alien Queen Chestburster Alien 3". Retrieved on 2013-04-25.
  6. 6.0 6.1 6.2 6.3 Vincent Ward (writer) and David Fincher (director). Alien3 [DVD]. 20th Century Fox.
  7. 7.0 7.1 Joss Whedon (writer) and Jean-Pierre Jeunet (director). Alien Resurrection [DVD]. 20th Century Fox.
  8. 8.0 8.1 Sandy Schofield. (1996). Aliens: Rogue. Bantam Spectra, 63. 
  9. Shane Salerno (writer) and The Brothers Strause (directors). Aliens vs. Predator: Requiem [DVD]. 20th Century Fox.
  10. Dave Hughes, Lee Brimmicombe-Wood. (1993). Aliens magazine, Vol. 2 #17. Dark Horse International, 43. 
  11. 11.0 11.1 11.2 Dave Hughes, Lee Brimmicombe-Wood. (1993). Aliens magazine, Vol. 2 #11. Dark Horse International, 31. 
  12. 12.0 12.1 S. D. Perry. (2014). Alien: The Weyland-Yutani Report. Insight Editions, 19. 
  13. S. D. Perry. (2014). Alien: The Weyland-Yutani Report. Insight Editions, 25. 
  14. 14.0 14.1 14.2 14.3 Dan O'Bannon, Ronald Shusett (writers) and Ridley Scott (director). Alien [DVD]. 20th Century Fox.
  15. A. C. Crispin. (1997). Alien Resurrection novelization. Warner Aspect, 91. 
  16. S. D. Perry. (2014). Alien: The Weyland-Yutani Report. Insight Editions, 18. 
  17. Alan Dean Foster. (1979). Alien novelization. Warner Books, 136. 
  18. Steve Perry. (1992). Aliens: Earth Hive. Bantam Books, 126. 
  19. 19.0 19.1  Aliens vs. Predator [Microsoft Windows, PlayStation 3, Xbox 360]. Rebellion.
  20. 20.0 20.1 S. D. Perry. (2014). Alien: The Weyland-Yutani Report. Insight Editions, 20. 
  21.  Aliens: Colonial Marines [Microsoft Windows, PlayStation 3, Xbox 360]. Gearbox Software.
  22. 22.0 22.1 Mark Kermode, Ridley Scott, Dan O'Bannon, Ronald Shusett, James Cameron, Jean-Pierre JeunetAlien Evolution [DVD]. Nobles Gate Scotland.
  23. 23.0 23.1 Ridley Scott, Dan O'Bannon, Ronald Shusett, H. R. GigerThe Alien Legacy [DVD]. Sharpline Arts.
  24. 24.0 24.1 24.2 24.3 24.4 "Monster Legacy - StarBeast — Part Ib: Alien, the Chestburster". Retrieved on 2015-08-07.
  25. 25.0 25.1 John Hurt, Ridley Scott, James Cameron, H. R. Giger, Dan O'Bannon, Ronald ShusettThe Alien Saga [DVD]. Prometheus Entertainment.
  26. 26.0 26.1 Ridley Scott, David Giler, Walter Hill, H. R. Giger, Dan O'Bannon, Ronald ShusettThe Beast Within: The Making of 'Alien' [DVD]. 20th Century Fox.
  27. 27.0 27.1 27.2 Matt Winston (September 5, 2013). "ALIENS Behind-the-Scenes - How the alien 'chestburster' mechanism was made. | Stan Winston School of Character Arts". Retrieved on January 22, 2014.
  28. 28.0 28.1 Jody Duncan. (2006). The Winston Effect: The Art and History of Stan Winston Studio. Titan Books, 88. 
  29. Cite error: Invalid <ref> tag; no text was provided for refs named LegacyStarBeastIa

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