Chestburster

"In a few hours it's gonna burst through your ribcage, and you're gonna die. Any questions?"

―Ripley 8, to Larry Purvis regading the Chestburster (from Alien Resurrection)

Template:Species Infobox The Chestburster is the infant (or nymph, because it resembles the adult and does not form a cocoon to reach maturity) stage of a Xenomorph. 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.

The Chestburster was first seen in Alien and was designed by special effects designer Roger Dicken, after the original concept by H. R. Giger was deemed unsatisfactory.

Characteristics

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 some speed. Some Chestbursters have been seen to possess arms, 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. In Alien³, the Chestburster seen at the beginning of the movie births fully formed, with arms and legs, essentially just a smaller version of the Runner that it subsequently developed into. Why this is so is not explained in the theatrical cut, although the extended Assembly Cut seems to imply the Chestburster was unable to escape its host's body (an ox) at the usual time, presumably due to the animal's stronger ribcage and chest structure, resulting in the premature death of the host and further development of the Xenomorph within.

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. Owing to the Xenomorph's tendency to assimilate a degree of its host's DNA as it develops, Chestbursters will also vary widely depending on the lifeform in which they gestate. For example, Xenomorphs born from Predators will feature the mandibles of their host at birth.

If born away the Hive, a Chestburster will actively search for a safe location to hide and a food source on which it can develop. It also will attack and kill humans and feed on them, although its proficiency in this regard is limited in the early stages of its growth. They will consume any part of the human victim (such as facial extremities or genitals), but prefer internal organs such as the brain, liver, or heart. Growth is rapid, and Chestbursters can mature into a full-grown Drone within a few hours. It will repeatedly shed its skin like a reptile as it grows, and these skins are often the most visible sign that a Xenomorph is nearby. Aliens: Steel Egg also shows that they do have regular body processes when one of the crew discovers a pile of excrement containing a human tooth while exploring the ventilation system. However, Chestbursters are adept at hiding and as such, immature Xenomorphs are rarely seen, remaining hidden until fully grown.

Gestation and birth

A Chestburster is generally implanted into its host by a Facehugger, although in Aliens vs. Predator: Requiem the Predalien was shown to be capable of inserting embryos directly into a host without the need for a Facehugger. It is speculated that Chestbursters develop in a manner similar to that of the immature heartworm (Dirofilaria immitis), which migrates through the host body absorbing nutrients before establishing itself. It's unknown if the embryo travels to the host's stomach or to the bronchial tubes. Another theory is that the Alien begins its life in the host body not as an embryo but as a tumor that later takes the shape of an immature Alien. In this theory, what the Facehugger injects in the host is not an infant Xenomorph but a small egg that inserts its proteins in the host's DNA and commands its cells to "create" the Chestburster which has both Xenomorph proteins and those of the host.

The host's characteristics determine the Chestburster's features — embryos are thought to copy 10-15% of the host's genetic code. This genetic absorption is designed to help Xenomorphs adapt to the environment in which they are born and leads to variations in the resultant creature. The Predalien Chestburster, for example, sports the signature mandibles of the Yautja (and grows dreadlocks upon reaching maturity), while quadrupedal hosts produce quadrupedal Chestbursters.

When fully developed, the Chestburster releases enzymes that softens the bone and surrounding tissues of the host's chest cavity 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. The process begins with cramp-like pains in the victim's chest but rapidly progresses to debilitating agony and uncontrollable convulsions. When the Chestburster finally emerges it induces severe shock and huge blood loss. Death is almost instantaneous, but unpleasant.

The Chestburster is arguably the most vulnerable stage of the Xenomorph's life cycle, and if born in a populated room a Chestburster will immediately seek escape (e.g. through open doors, air ducts or vents, possibly going as far as burning a hole in a wall or floor with its acidic blood). Stasis is known to halt Chestburster development, as seen in the 2010 video game Aliens vs. Predator when Corporal Tequila is placed into hypersleep to prevent the embryo inside her from birthing.

Survivability

While the birthing of a Chestburster is inherently fatal, in Alien³ it is said to be possible to remove a Chestburster before it emerges with no long-term residual effects to the host. This procedure is later shown at the beginning of Alien Resurrection, when a Xenomorph is successfully removed from Ripley 8, who then goes on to make a full recovery (although owing to her altered genetic structure, it is unclear how true this statement would prove to be for a normal human).

Conversely, Aliens: Colonial Marines claims that even if a Chestburster is successfully removed from a host, the host will later die anyway as the placenta the Xenomorph creates during development is highly cancerous and quickly fatal. It is not elaborated upon whether removing an embryo at an incredibly early stage would prevent this.

Prior to Aliens: Colonial Marines, the successful removal of a Chestburster from its host was often shown in many comics, including Superman/Aliens, Dredd vs. Aliens and Batman/Aliens II. However, these comics are not canon. An attempt to remove an embryo is also shown in the 2010 video game Aliens vs. Predator, when the android Katya uses some equipment to stabilize Corporal Tequila, however, Karl Bishop Weyland shuts down the device's power before the removal operation can be completed.

A noncanon example exists in the Alien: Resurrection video game in the form of the Auto-Doc item, which kills and removes a developing Chestburster from the host body using targeted radiation. Whether this is an effective treatment for impregnation is unknown, as it is only shown in this game in response to the fact that the player can be facehugged.

Another non-canon theory about a survival from an embryo was shown in the Batman/Aliens II comic. The female antagonist Dr. Fortune got impregnated by a Facehugger but the chestburster was unable burst out from her body because by the time she got impregnated, she was suffering from leprosy which resulted in a stunted embryo (later revealed to be a Queen) As a side effect, it granted Dr. Fortune enhanced strength (similar to Ripley 8). Later the xenomorph embryo seemed to have become deformed and the outline is visible seen on her stomach.

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.

Gallery

A Yautja spawned Chestburster.

A quadrupedal animal spawned Chestburster.

The Chestburster extracted from Ripley 8 in Alien Resurrection.