(Press photo to zoom!) • Universe: Predator & Alien
• Name: Alien
• Species: Xenomorph
• Place of Origin: Home World - Xenomorph Prime
• Reproduction: Through implantation of an endoparasitoidic embryo into a living host
Life cycle includes alternation of generations and metamorphosis
• Behavior: Displays predatory behaviour towards any living lifeforms, usually using stealth tactics to ambush its prey
• Connections:Predator (Adversary)
The Xenomorph XX121, better known just as Xenomorph or the "Alien", is an extraterrestrial hive-based endoparasitoid species with a multi-staged life cycle, possibly originating from the planet Xenomorph Prime.
One of the deadliest of all known alien species, these creatures require a host organism in order to reproduce. The appearance of the Xenomorph can vary depending on the host in which the embryo is implanted. The Human phenotype is generally around 7–9 feet (~ 2.13 - 2.74 meters) in height and roughly 181.43 to 272.15 kilograms (400-600 pounds) in weight, with a long, muscular tail and large, curved, oblong head. The Queen of this species is generally twice as large (although some Queens have been shown to grow even larger, some surpassing 30 meters in height if given time) and possesses superior speed, strength and intelligence compared to her common offspring.
The physical form of a Xenomorph can vary widely depending on its life stage, hive, caste, age, and host. Its ability to incorporate genetic material from its host, coupled with the existence of numerous mutations and deviations which have originated naturally or artificially; makes the Xenomorph one of the most phenotypically diverse organisms in the galaxy.
A typical Xenomorph begins its life cycle as an egg-like creature (known as an ovomorph or simply egg) which, when detecting the presence of a potential host, opens up to release the second stage: a small arachnid-like life form (named the facehugger) which launches itself onto the host's face and impregnates it with an endoparasitoid larva. This parasite then consumes parts of the host from within and violently emerges from the host's chest cavity as a worm-like creature (grotesquely christened as the chestburster), which will quickly scurry away to find a safe place where it can molt and complete its metamorphosis into an adult Xenomorph, which happens, surprisingly enough, over the course of mere hours.
Adult Xenomorphs all tend to share some common traits: a vertebrate-like body, a protective dark exoskeleton, a long flexible tail, an elongated domed head and a toothed mouth hiding a secondary, extendable, proboscis-like inner maw. Little is known about their biology, but it is known that they eat with their inner or secondary mouths, not their outer mouths. This mouth is somewhat similar to the pharyngeal jaw of a moray eel. They also bleed an unknown and extremely corrosive fluid. This substance is dull yellow in color and often referred to as "blood", although whether it's used to transport nutrients through the body and/or serves principally as a defensive mechanism is not clear. While the extremely corrosive fluids and tremendous resilience displayed by the creature might suggest an exotic kind of biochemistry, the fact that the Xenomorph not only feeds on Humans, but actually develops inside them, strongly suggests that its biology is carbon-based. The ability to inherit traits from its hosts also suggests that it incorporates genetic material from them, implying that the Xenomorph either has DNA, or is able to read and convert DNA into whatever means it uses to store genetic information. There is evidence that the genetic exchange is mutual (i.e. the parasite alters the host's DNA as well), given that Ellen Ripley's clones were created in an attempt to gain access to the Xenomorph Queen's genetic material, which wouldn't be possible otherwise.
Xenomorphs operate in hives made of a resin they produce, mixed up with their saliva fluids. The Queen can be generated in more than one way: from specialized royal facehuggers, or maturing from Praetorians, which in turn can mature from Drones or Warriors; by a process referred as 'molting'. Judging from the condition that any Xenomorphs can potentially 'molt' and grow into a Praetorian and then a Queen, the Xenomorph species is likely all unisexual and reproduces asexually by a process called parthenogenesis: a reproductive method practiced by many species on Earth and other planets. Alternatively, it's also possible that the aliens are either hermaphrodites or practice sequential hermaphroditism, i.e. being able to change sexes during life, as is the case with some species of fish and amphibians.
Most Xenomorphs appear to possess an intelligence level equivalent to that of a typical primate. It's well within their capabilities to learn relatively quickly, gathering information and making advantageous use of their environment. Although they do not demonstrate Human and Yautja-level intelligence as a species (such as abstract reasoning, introspection and technological advancement), their Queen appears to possess considerable acumen in her social behavior and manipulation of Human technology, such as cutting the power of the LV-426 colony and operating an elevator. While it may take considerable time for them to learn how to operate machinery, other Xenomorphs have displayed fast reasoning and the capacity to find creative, counter-intuitive solutions to problems, as exemplified by a group which, after noticing that they were being contained, intentionally murdered the weakest so that the acid of the Xenomorph's blood would eat through the floors.
As the adult Xenomorphs are known to inherit physical characteristics from their hosts (for example, when a Yautja was infected, the parasite later developed into a "Predamorph" or "Predalien") it is possible that the intelligence level of the creature may be influenced by its host as well. Furthermore, being an eusocial species, it is possible that the intellectual capacity varies for each different caste.
Xenomorphs have demonstrated little emotion, though they are not completely devoid of fear, such as when they are in the presence of fire, which they are vulnerable to. They have also been shown to communicate pain through shrieks or screams when attacked.
The adult Xenomorph is a living weapon, noted for their ferocity and deadliness in any condition. Once fully matured, they have great physical strength and agility. They are masters of stealth; a favored method of acquiring prey is to wait in a dormant state until an appropriate victim strays near, and then drop down silently from behind or use their tail to impale whoever walks by. The prey is generally blind to the fact that a Xenomorph is present, due to its propensity to camouflage itself within its nest walls or the surrounding artificial environment, given their biomechanical-like appearance. The Xenomorphs will also use their pitch black carapace to their advantage, lurking in the shadows whilst waiting for prey to stray too close.
Xenomorphs are shown to be able to take extreme amounts of physical damage that would kill any earthly life form. An example of this is a Queen that survived a multi-ton exo-suit falling on her from over 30 feet. Xenomorphs are capable of surviving with limbs shot off, stabbings and even shots through the head (though total decapitation kills them).
Adult Xenomorphs are quick and agile, and can clamber along ceilings and walls: a skill they exhibit freely whether they are evading others, attacking, or hunting. They can survive in extreme temperatures, are well-adapted to swimming, can respire in harsh atmospheres, and can survive in vacuum for indeterminate lengths of time. Their movements tend to be silent, and they do not radiate heat as their exoskeletal temperature matches the ambient temperature. They also salivate profusely. This saliva is not acidic, though some Xenomorphs do have the ability to spit acid, which may come from their stomachs, a special gland somewhere in their throats, or acid pouches lining the head. This can be used to blind victims, much like a spitting cobra. Due to the absence of clearly visible eyes, it is possible that the creature uses echolocation to see its environment, much like bats. It may be for this reason that Xenomorphs hiss almost constantly, though there is evidence that they can detect light and darkness as well. Xenomorphs may be able to find their prey through electro-reception. This is the method sharks use to detect even the most hidden prey. Creatures with the electro-reception sense can detect the electromagnetic field all animals produce, allowing them to locate their prey by its heart beats, even if the prey is immobile. This would explain how Xenomorphs always know where the Humans are. Furthermore, the Xenomorphs can also detect whether a potential host is already infected, likely by sensing pheromones.
Xenomorphs produce a thick, strong resin, which they use to build their hives and cocoon victims. Cocooning is a trait used by Xenomorphs to reproduce quickly. A Human, or any other creature, if dragged away, may have a cocoon of saliva and resin placed over them (their face left free), usually in an area where the Queen has produced a large quantity of eggs, so that the facehuggers are able to latch onto them easily and deposit a Xenomorph larva inside their chest. Much like termites, they mix their viscous saliva with solids. It shows amazing heat and moisture-retaining qualities.