The facehugger is the second stage in the life cycle of a Xenomorph. Its bony finger-like legs allow it to crawl rapidly and its long tail can launch it in great distances. These particular appendages give them an appearance somewhat comparable to chelicerate arthropods such as arachnids and horseshoe crabs.
The facehugger is a parasitoid; its only purpose being to make contact with the host’s mouth for the implantation process. The Facehugger secures its eight finger-like appendages tightly around the head of its victim and wraps its tail tightly around the host’s neck, eliciting a gasping response and allowing the insertion of an ovipositor into the host’s esophagus. An embryonic form of the Xenomorph is then implanted directly into the stomach of the host. During the implantation process the host is fed a constant supply of oxygen via two lung like organs. Attempts to remove the Facehugger result in the parasite tightening its tail around the host’s neck, almost as a threat of death if not allowed to continue the implantation process. Another deterrent is its highly pressurized molecular acidic blood which sprays wildly if the parasite’s skin is cut into, ensuring that if it is removed from the host surgically the host will suffer catastrophic burns, almost certainly leading to death.
As the implantation process nears completion the facehugger’s epidermis solidifies into a chitinous layer of silicon, presumably in an attempt to ensure the success of the implantation. Once the embryo is safely implanted, the parasite detaches from the host and retreats to die in seclusion. Eventually, the larval form of the Xenomorph, known as a Chestburster, will violently erupt from the host’s chest cavity, resulting in a gruesome and excruciating death.
While still residing within the Ovomorph, the facehugger appears to possess the ability to assess the physical viability of a potential host, including being able to discern the difference between living and artificial beings. The parasite will generally avoid hosts with obvious deformities or maladies, choosing instead to remain within the Ovomorph.
The Facehugger greatly resembles a pair of skeletal hands fused together, with a spine-like tail. 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 Chelicerate arthropods such as arachnids and horseshoe crabs. The underside of the Facehugger and its orifice (from which extends a proboscis used for delivering the Xenomorph embryo) noticeably resemble a human female’s vagina.
A Facehugger’s long digits allow it to move rapidly across all manner of surfaces and also grant the creature its crucial ability to “grip” a host’s head during implantation. The spindly appearance of these digits should not be underestimated; they are incredibly strong, and have been known to tear the skin from the skulls of human victims when an attempt is made to remove them. Once the digits are gripped around a host’s head, they are nigh impossible to remove and implantation is virtually guaranteed. A Facehugger’s tail can propel the creature into huge leaps and is also used for additional grip around a host’s neck during implantation. Facehuggers have even been known to use their tail to strangle potential hosts when attempts are made to remove them, sometimes fatally. Their potent acid blood further complicates any attempt at removal. Facehuggers are primarily beige in color, giving them a skin-like appearance.
Situated on either side of the creature’s body at the base of the tail are a pair of bag-like bladder structures that are used to circulate air into the victims lungs during implantation. Underneath the Facehugger is a small orifice, from which the creature will extend a lengthy proboscis into the host’s throat for implantation. While fragile and useless in combat, Facehuggers’ small size and rapid movement makes them adept at ambushing potential hosts, and also makes them difficult to kill. Facehuggers have been known to be used in an actively offensive role when transported by a Carrier.
Prior to detecting a host, Facehuggers are actually inert and lifeless within their Ovomorph. When the Egg detects a host nearby, it will transfer all of the remaining bio-electric potential of its acidic blood to the Facehugger, and it is only then that the creature becomes “alive”. The Egg will then open and the creature will launch itself at the victim.
Once outside of the Egg, Facehuggers use a similar set of thermoauditory senses as the adult Xenomorph to track and close in on their prey.Typically, Facehuggers rely on the curiosity or ignorance of the potential host to draw them near to the Egg prior to release, thereby allowing for a lightning-fast pounce that gives the victim virtually no time to escape. However, they are more than capable of pursuing a fleeing host, an act they will carry out with relentless persistence; Facehuggers will chase down their prey with little consideration for their own safety or survival. They are adept climbers and jumpers, using these abilities to quickly overwhelm their victims before they can react. Although Facehuggers can survive outside of their Egg without implanting for a period of time — up to 120 hours has been recorded — this is not thought to be common.
Facehuggers are not deterred in the least by their host’s death should it happen despite their determination in getting to them in the first place, they will simply detach from the body and will chase the nearest living suitable host. However, the window for this chance depends on whether or not the parasite had already “implanted” it’s host given that most Facehuggers will eventually die afterwards, the creature will be rendered useless.
Being submerged does not appear to affect their ability to operate, as Facehuggers on LV-426 were stored in an alkaloid nahcolite preservative fluid for an extended period of time and were still able to function normally when released. They are also capable of healing incredibly quickly, cuts and lacerations closing within minutes without leaving any trace of permanent scarring.