The COMPLETE Xenomorph Biology

Below is just about everything which you need to know about xenomorphs. I may elaborate on certain situations from time to time, but this is it. I will also add a section proposing and disproving other theories later.

Section 1: Eggs

Physical Description
Xenomorph eggs are simple, oval-shaped objects which appear to be made out of a flexible, organic material. Each egg is topped with a four-piece aperture, which resembles the bud of a plant. These eggs are soft and leathery in build to better absorb physical abuse and prevent damage to the facehugger within. They are still fragile, however, and are also surprisingly flammable. As a xenomorph egg ages it will also sprout root-like tendrils for drawing nutrients.

Development
Xenomorph eggs have been known to be produced in two different ways: either within a queen or from a living host. Whilst all types of xenomorph eggs may develop within a queen simply through nourishment and diploid meiosis, only eggs containing standard facehuggers can be created from another organism. When first spawned, a xenomorph egg contains enough nutrients for the facehugger to feed off of to exist in a dormant state for an undetermined period of time. As the facehugger feeds on this source of nutrients, the egg slowly develops tentacles to leech raw nutrients and minerals from its surroundings. This allows an egg to continue to nourish its facehugger for a nearly infinite period of time.

Behavior
Xenomorph eggs only respond to the stimuli of unfamiliar pheromones. When these are detected, a xenomorph egg's organic petals spread apart via a nervous impulse, exposing and rousing the facehugger within.

Section 2: Facehuggers

Physical Description
Facehuggers are equipped with a total of eight legs, each of which are triple-jointed. While very effective for movement, each leg is also very long in length and rather strong, allowing for great leaps and sudden ambushes. Each facehugger also possesses a long, powerful tail, which also serves as an additional springboard for leaps. Like adult xenomorphs, facehuggers possess a highly acidic fluid for blood, though their bodies are composed of ligaments and tendons more than anything else. They are also completely blind, but their bodies are extremely sensitive to any sort of sonic disturbance, enabling them to pinpoint their prey solely based on the sounds they may generate. They can likewise discriminate between xenomorphs and other organisms from the pheromones which they exhibit.

Behavior
Facehuggers exist solely to implant a single host with a potential xenomorph. Upon arousal from an egg, they immediately seek out a nearby host, leaping from their eggs to latch onto the mouth of any organism they can locate. Because most sounds generated by an organism are through this orifice, this process is usually incredibly swift and accurate. However, while the actual level of intelligence a facehugger may possess is unknown.

Once a facehugger latches onto its prey, it inserts a long proboscis down the victim's pharynx and provides its host with only enough oxygen to allow it to remain alive yet unconscious. While it is doing this each leg wraps around the victim's head, and the tail coils about its prey's neck, making the facehugger difficult to detach. If prematurely removed, a facehugger's tail will impulsively tighten around the neck of its victim, killing the host in the process. Upon securing itself to its host, the facehugger deposits a single premature xenomorph through its proboscis into the victim’s pulmonary artery via the lungs. Shortly afterwards the facehugger, having spent all of its energy laying the xenomorph embryo, expires and releases itself from its former host.

Development
Facehuggers simply do not develop in any known way throughout their lifespans.

Variations
Queen facehuggers (a.k.a. Super facehugger) have been reported, though their exact behavior is not entirely known. These appear to be larger, faster facehuggers, possessing spikes to make their removal more painful and difficult. Unlike the standard facehugger, which dies after one implantation, a queen facehugger is capable of depositing multiple xenomorphs into several hosts, as well as one queen, before it expires.

Section 3: Chestbursters

Physical Description
Upon being birthed, a chestburster resembles a small, serpentine organism bearing only a handful of xenomorph traits. They do not yet possess legs and their arms are too underdeveloped to serve any purpose, and as such can only support themselves upon a long, ribbed tail, with which they are capable of slithering across even the smoothest of surfaces at extremely rapid paces. Chestbursters normally do not exude any sort of neck, though the smooth dome which will eventually become a head is evident. Like adult xenomorphs, chestbursters are capable of sensing mental, sonic, and light waves. However, because of their small size and lack of appendages, they do so with their entire bodies rather than through specialized sensors. They also possess acidic blood, and their vital organs are simply underdeveloped versions of those of an adult xenomorph.

Development
After implantation via a facehugger, a chestburster develops within a by leeches off of the pulmonary artery, which supplies oxygen-rich blood from an organism's lungs directly to its heart. Upon insertion into its new environment, the chestburster immediately adopts the host’s blood type and genetic makeup to prevent any immune systems from recognizing it as a foreign threat. As the chestburster continues to develop it also picks up several other physical traits of its host, modifying these phenotypes until it has perfected its premature form and genetic makeup.

Once the chestburster has grown too large to remain parasitic, it must violently expel itself from the host. Because it must be located at a point within the host which is normally not accessible via any orifice, a chestburster must dig its own way through by using its newly developed teeth to eat its way through the host’s torso. After enough of the host’s innards have been devoured to leave little resistance to the chestburster, it violently thrusts outward, exploding from its host and into the outside environment.

Once the chestburster has left its host and maintained a degree of safety, it begins to grow at an extremely rapid rate. Through shedding its skin and consuming the removed flesh for protein, a chestburster may develop at an extremely fast pace whilst remaining self-sufficient and providing itself with enough nutrients to survive the duration of the growth. As it continues to shed its limbs sprout and grow in length, and its flesh toughens and becomes more distinct until its period of growth is complete. If a danger presents itself before this shedding is complete, however, it will leave the skin unconsumed, and must find its nutrients elsewhere.

Behavior
Chestbursters behave with the sole concern of self-preservation in mind. Significantly more intelligent than facehuggers, chestbursters immediately seek shelter or protection upon breaking free from their hosts. If a chestburster is unable to detect any xenomorphs to protect it, it will release one or more distress cries in an attempt to summon any nearby drones to its aid. If none can be found, or inown organisms are within its proximity, the chestburster will immediately flee from its host and relocate itself in a safer environment.

Variations
Based on the traits adopted by its host, a chestburster may greatly vary in appearance than that described above. They rarely display negative phenotypes, however, unless such traits would prove to be beneficial in another way.

Queen chestbursters also vary significantly from standard chestbursters. Their bodies are more heavily plated than their lesser brethren, and their crests are surprisingly noticeable prior to development. Also, unlike standard chestbursters, queen chestbursters adopt only enough of their host’s genetic pattern to avoid hostile immune system responses, and as such exhibit no assumed traits or genetic modifications. They also take much longer to develop.


Section 4: Xenomorphs

Physical Description

All xenomorphs possess three layers of protection: the epidermis, the mesoskeleton, and acidic blood. A xenomorph's epidermis, which is usually black in coloration, is a xenomorph's first layer of protection against outside assaults and ailments. Its color serves as a natural camouflage, and its slick surface makes it difficult to puncture and provides ease of movement in constrained spaces. A xenomorph's epidermis is also resistant to acid, and can withstand temperatures beyond boiling or below freezing.

The mesoskeleton is a xenomorph's primary defense against extreme levels of physical abuse. While similar to an endoskeleton, a xenomorph's mesoskeleton not only supports its internal organs, but also protects the muscles located in its appendages and provides the basic figure of a xenomorph body. The mesoskeleton is extremely light in weight, though its resilience has been slightly compromised when compared to the bones of other organisms. Like the epidermis, the mesoskeleton is acid-resistant.

The final and most potent defense of any xenomorph is its acidic blood. While comparatively similar to the blood located in other organisms, the plasma in a xenomorph's circulatory system is extremely acidic, making it highly dangerous when exposed to an outside environment. All xenomorphs, however, are immune to the effects of acids, making this defense solely beneficial.

Xenomorphs are humanoid in shape, possessing a head, torso, two arms, two legs, and a tail. Every xenomorph bears these traits, though varieties are not unknown.

The first and most noticeable feature of any xenomorph is its head. Smooth and elongated in shape, and, while xenomorphs do not have eyes, their jaws are more than impressive. A xenomorph’s teeth are sharp and pointed to enforce their carnivorous nature, and within every set of jaws xenomorphs also possess a secondary mouth in place of a tongue. These jaws, which are much smaller and simplistic than the xenomorph's primary set, are attached on the end of a powerful retractable stalk, which possesses enough penetrating power to punch through flesh, bone, and even certain metals. The mouth of a xenomorph is also rather unique because, unlike most other creatures, the epidermis which binds the upper and lower jaws exists to actually prohibit the jaw from opening too far, in addition to containing food within the mouth. Without these bindings it can be assumed that a xenomorph's maw may become dislocated during an action or violent motion, rendering its jaws entirely useless.

A xenomorph's head is connected to its torso by a long, flexible neck. Their necks are composed of multiple tendons, muscular bundles, and arteries, all of which are highly visible just beneath their flesh. Their necks must be both powerful to support their massive heads, and long in length so as to allow the xenomorph to turn its head upward while keeping its sloping cranium clear of its back.

Xenomorph torsos are typically very narrow and angular, with the rib cage being clearly visible to the naked eye and a smooth, raised collar of bone to protect their more fragile necks. Because xenomorphs do not possess lungs, this protective structure exists primarily to protect the xenomorph's torso from being crushed by physical abuse. To further exploit this protective covering, certain breeds of xenomorph have begun to exhibit an evolutionary adaptation which allows this rib cage to slope back and merge into their backs, further protecting their torsos from physical harm.

A xenomorph's lower torso, not enclosed within a bony structure like the upper portion, is very thin, lined only by a spinal column. A xenomorph waist is likewise very angular in shape, closely resembling the basic shape of a human pelvis.

A xenomorph's arms are slender and powerful in build, with the mesoskeleton lying directly beneath the epidermis. These arms are typically humanoid in shape, ending in powerful, and at times oversized, hands. Additionally, a xenomorph's arms have unique sensory organs, which will be described later on in the section.

A xenomorph's hands vary greatly in appearance, primarily due to the degree of gravitational force which the xenomorph must develop in. In areas of low or no gravity, a chestburster will adopt the genetic patterns necessary to develop into a xenomorph with five or more fingers to ensure ease of movement and improved dexterity. In areas of higher gravitational force, however, xenomorphs instead develop powerful, oversized hands possessing two fingers and two thumbs to better grasp, claw, and manipulate their surroundings or prey.

On the back of every xenomorph are four long, curved tubes, which also occasionally possess sensory organs akin to those on their arms. These tubes provide two functions, with the first and most obvious being protection. Composed of the same material which forms the xenomorph's mesoskeleton and spread apart to accommodate the xenomorph's sloping head, these tubes bestow the xenomorph with protection against attacks from the rear while enabling the xenomorph’s head to remain capable of tilting upwards.

The second function of these tubes is the ability to release oxygen to prevent explosive decompression. Because xenomorphs do not possess lungs, they instead take in air from their environment through their mouths to generate speech. Through a set of muscular contractions, xenomorphs are capable of creating lower air pressure within themselves, forcing the air around them to be pulled in through their mouths. After flowing through through their espophagus and into a modified trachea, this air is pushed over the xenomorph’s vocal chords after the same muscles relax and reverse the flow of oxygen, allowing them to generate sound. In cases of extreme atmospheric decompression, a xenomorph can impulsively open a set of valves leading out from the the muscular glands which allow them to take in air, allowing the oxygen to escape through their tubes and their mouth simultaneously.

Sprouting from the back of every xenomorph's lower torso is a long, slender tail. These appendages are likewise plated by the mesoskeleton beneath their epidermis, but unlike a xenomorph's other appendages this plating is frequently segmented to enable flexibility and freedom of movement. At the end of their tails, every xenomorph possess a barb-like claw. In areas of moderate or high humidity, however, xenomorphs will also develop extensions of their mesoskeleton near the end of their tails much akin to a human’s spinal column, as well as a much larger and more blade-like claw. This adaptation enables the xenomorph to move with ease in aquatic environments, though it is rarely developed in dryer locations due to its increased weight.

A xenomorph's legs are likewise humanoid in shape and underlain by their mesoskeleton, but, unlike their arms and tubes, the sensory organs located on their legs are significantly larger in size.

A xenomorph's feet are yet another example of environmental adaptation. Normally being humanoid in shape, every xenomorph’s foot possesses four clawed toes facing the front of the foot, as well as a single clawed toe which is located at the heel. This toe, which stabilizes the xenomorph on steep downhill surfaces, is also used when leaping atop of prey or other objects. When a xenomorph is spawned in areas of high humidity, however, three larger toes are developed on the front of the foot instead of the usual four, with each of these being slightly webbed to aid aquatic movement.

Internal Systems

As previously mentioned the plasma within a xenomorph's blood is highly acidic and serves as a means of defense. However, a xenomorph's blood also exists to nourish the xenomorph, keeping the organism alive throughout the duration of its lifespan. Because xenomorphs do not possess any sort of respiratory system, their circulatory systems are designed to function solely upon the oxygen which is provided by their diets. This includes a multi-chambered heart, which enables a xenomorph to pump blood through their circulatory systems with very little oxygen expended. This organ’s structuring is always retained, regardless of phenotype adoption, because of its functionality. Additionally, a xenomorph's circulatory system is extremely resilient, and can withstand and function while experiencing drastic changes in the volume in their blood stream, enabling them to comfortably exist in the vacuum of space.

A xenomorph's digestive system always differs based on their initial host, but every system is additionally designed to absorb oxygen from their consumed food and directly introduce it to the blood stream. This creates the need for xenomorphs to consume food on a regular basis during periods of activity, as well as require a carnivorous diet. Additionally, while xenomorphs do require moisture, and though they do acquire all the liquids they need through their food, their digestive systems do combine the fluids they consume with bodily chemicals which are bonded from synthesis to expenditure, allowing the xenomorph to keep the boiling point of its consumed fluids drastically high and unaffected by the vacuum of space. When there is not enough food for the xenomorph to remain functional, it assumes a state of hibernation, which it can maintain for extremely long periods of time. Unlike many advanced organisms, a xenomorph actually exudes its waste through the mouth in the form of resin. Normally stored within a gland located in the chest cavity, a xenomorph's resin is a peculiarly sticky substance which, when introduced to an outside environment, becomes surprisingly malleable and slowly decomposes. As it does so, the resin's decomposition alters the atmospheric conditions in the surrounding area, making it both warm and humid.

While xenomorphs possess no excretory or respiratory systems, their nervous systems are perhaps the most advanced of any known organism. In fact, a xenomorph's head is specifically designed to receive and translate sound waves. When these waves strike the head of the xenomorph, because its smooth shape, the sound waves are instead absorbed into the skin rather than reflected. They are then transmitted through a special layer of fluid beneath the cranial epidermis, where the waves can be translated into nervous impulses with enough accuracy to pinpoint objects and organisms. Additionally, xenomorphs possess multiple regions of light-sensitive flesh, which can be located on their arms, legs, and other areas of the body. These not only detect the presence of light, but also detect an extremely wide set of wavelengths, allowing the xenomorph to perceive its surroundings in multiple spectrums. Their flesh is also extremely sensitive, making them very alert to changes that would otherwise not be noticeable. A xenomorph's brain is very large in size, with large portions solely dedicated to the detection of stimuli. They also possess unique olfactory receptors within their throats, and possibly on other regions of their bodies. These enable them to differenciate xenomorphs from different hives when physical appearances prove to be too similiar.

Xenomorphs do possess reproductive organs, but they remain sterile for the majority of their lifespan. While a female xenomorph's reproductive organs are internalized at all times, a male's remain only so when they are not in use. That aside, a male xenomorph’s reproductive organs are nearly identical to that of a human's, while female xenomorphs reproductive organs remain underdeveloped and nonfunctional so long as another queen is present. These organs remain unchanged, regardless of phenotype adoption, because of their functionality.

One peculiar trait which all xenomorphs possess is that, while they are extremely active organisms, they are neither endothermic nor ectothermic. This enables xenomorphs to survive not only in the vacuum of space, but also in subzero or superheated conditions.

Variations
Xenomorphs vary greatly in appearance based on what host they have emerged from, as well as what conditions they developed in. The xenomorphs previously described are those spawned from human hosts, making the variations vast and, in many ways, endless.

Drone Xenomorph

Xenomorph drones are physically identical to those described above, and serve as the backbone of any xenomorph colony. Drones remain sterile until they ascend to the next level in the caste system.

Female drones are also capable of producing eggs in the absence of any other xenomorphs. Unlike a male xenomorph’s resin, a female’s actually forces foreign organisms to undergo an involuntary metamorphosis. This transforms the victim into an egg, allowing the drone to produce additional xenomorphs prior to her own ascension to a queen.


Behavior

Typically, a xenomorph drone obeys the commands of the queen, but in her absence a drone becomes primarily concerned with its own self-preservation and spawing a new hive. They are shockingly intelligent and cunning, and are capable of communicating with one another.

Development
Aside from what is mentioned below, xenomorphs do not develop much further beyond this point, though they do molt occasionally as they age and grow in size.

Warrior Xenomorph

When a male xenomorph drone ages and grows, it eventually becomes sexually mature and is treated as a xenomorph warrior. Fueled by hormones and fully developed, xenomorph warriors are significantly stronger and more aggressive than their drone underlings. Their heads, which have lost a portion of the cranial fluid which is used in sonic translation, are ribbed from the mesoskeleton beneath, and possess a small pressure vacuum. While this compensates their ability to translate sound waves, it also makes their heads much more resistant to physical abuse.

In addition to these physical developments, warrior xenomorphs also gain a new form of attack. Having aged considerably since their spawning, every warrior xenomorph has developed a unique set of glands located just behind their mouths. These unique glands, which slowly produce an extremely potent digestive enzyme, enable the warrior to accurately fire a very corrosive and adhesive fluid over short distances via powerful muscle contractions.

Behavior

Warrior xenomorphs are behaviorally akin to xenomorph drones, but they also possess their own form of hierarchy within the hive. The most powerful and capable warrior, known as the alpha xenomorph, is considered the dominant male, and is the only xenomorph which is permitted to mate with the current queen and maintain her resin supports.

Queen Xenomorph

A queen xenomorph's body functions in such a way that she serves as the focal point of a hive. Her head, which is now protected by a colossal crest of flesh and bone, is significantly larger, possessing a cowl in which she may protect her face. Her body is significantly larger and much more complex, with a second, smaller pair of arms designed for resin manipulation. Her tail is also noticeably longer in length, ending with a larger claw than those possessed by her offspring.

A queen xenomorph is the only female xenomorph within a hive which is sexually active. Upon mating with the alpha xenomorph, she stores her mate's sperm within glands in her pelvis for future use. Her ovaries, which are located both in her pelvic region (for the production of super facehugger eggs), as well as her abdomen (for traditional eggs), nourish the developing eggs with nutrients she consumes from the outside environment. When the eggs have fully matured, they are released from the queen's ovaries and are deposited through her abdomen through different ducts than that which she uses for mating. This enables her to continue to mate with the alpha xenomorph when necessary and still produce eggs. After traveling to the end of her abdomen, they are released into the outside environment through a unique muscular appendage. She also deposits her resin through this appendage, using it to safely secure her eggs to any surrounding surfaces. When the queen is detached from her abdomen, either through voluntary action or due to physical harm, she is still capable of laying super facehugger eggs, which, as previously mentioned, mature within her pelvis instead of her abdomen.

Behavior

Upon emerging as a fully developed organism, the queen begins her new life by creating a massive set of supports to uphold her body and her abdomen after fertilization. Unlike other xenomorphs, the queen exudes her resin through the end of her abdomen, which she then manipulates with her smaller and more dexterous inner arms. This resin will later be maintained by the alpha xenomorph.

The queen's mindest has ascended to much more brooding and intelligent level upon development, and unlike other xenomorphs in the caste system, the queen’s primary concern is preserving her offspring and ensuring that the current hive survives. She even has a basic understanding of technology, and is intelligent enough to know when to back down from a fight.

Development

In the absence of a queen, a female drone's natural instinct to ascend to the highest level of the xenomorph caste system remains unsuppressed by pheromones. Because of this, the female xenomorphs begin to molt at an accelerated rate, much as the did as they were chestbursters, their bodies becoming both significantly larger and reproductively capable. During this time, the female drones become remarkably aggressive toward everything around them due to their unregulated horomones, and will kill one another until only a single dominant female remains to become the new queen.

Upon completing her final transformational molt, the new queen either kills or drives out the previous alpha male, choosing a new mate to begin her hive's brood anew.

Initially mobile, the queen's abdomen remains relatively small within the first stages of her new life, but with every molt her abdomen adds on a new set of ovaries, causing it to get larger over time. Eventually this grows to be so immense that she becomes completely immobile, and can only be moved through a collective act by her brood. Even then, such an action is extremely rare, and will only be performed if she requires more room or her has been located in an inconvenient location.

Questions and Answers

1) Xenomorphs are telepathic

Crow: No. Xenomorphs possess no sort of mental link with one another, and are not capable of telepathy. If they were, then they would have absolutely no need to be so vocal.

2) Xenomorphs communicate with pheromones

Crow: No. If they did so, then the yautja would have already cracked the pheromone code and used it against the xenomorphs during their hunts. This would also eliminate the need for them to be vocal. The xenomorph queen does, however, use pheromones to prevent her drones from being capable of transforming into queens in order to prevent overpopulation or conflict. They also use pheromones to distinguish one another as being part of a hive.

3) Xenomorphs need to breathe

Crow: No. If xenomorphs needed to breathe, then they could not survive in the vacuum of space.

4) Xenomorphs do not have genders

Crow: Once again, this is false. If xenomorphs did not have any sort of gender, then their mutation rate would be far too limited, and the species would ultimately never be able to survive. Additionally, the illustrations made by H.R. Giger clearly display xenomorphs with genitalia.

5) The xenomorph queen can regenerate her abdomen

Crow: No. Just as how xenomorph drones cannot regenerate lost limbs, the queen cannot regrow her abdomen. Once it is gone, she is forever unable to reproduce normal facehuggers for the hive.

6) The resin-coating within a hive is designed to carry sound waves

Crow: Yes. Because xenomorphs communicate vocally, they design their colonies to carry sound over extremely long distances, enabling them to hear intruders and listen for orders from the queen. Additionally, the resin is used to make the living conditions of the hive more comfortable for the xenomorphs, as well as provide them with ample ambush locations.

7) Xenomorphs were made by the Space Jockeys

There is absolutely no proof that this is true in any way. Also, the cloning process in Alien: resurrection thoroughly disproves the possibility that their genetic code was created by advanced artificial means.




Forget the freak,
I'm just nature.