The Facehugger encountered on Planet 4, by the crew of Covenant, is virtually identical to its facehugger cousins. However, there are plenty of notable differences in cosmetics and in function. The Facehugger is generally considered to be the second stage in the life cycle of the Xenomorph species and this variant fulfills the same role with the Planet 4 strain.
The Planet 4 variant of the Facehugger incubates within an Ovomorph, has roughly the same shape as other variants, but has a different appearance and "skin" pattern as the normal reddish, wrinkled area between the forelegs is replaced by a flat, smooth surface, with the same coloration as the rest of its body. The facehugger's digits are notably different as they are thinner and while their actual span may be the same as its later XX121 cousin, the length between each knuckle is different, notably the size of the digits from the body to the first knuckles is smaller and has some sort of flesh or tendon extending from the first part of the digit to the other, just beneath the first knuckle. The parasite's air sacs are also visibly different, being bumpy and more solid looking when compared to the smooth, untextured appearance of its cousins.
Aside from the cosmetic differences, these Facehuggers functions and behaves differently. For example it possess incredible speed and agility that is arguably faster than its other versions, making it nearly impossible to shoot even with an automatic rifle. However, it seems to be inferior in some ways as while it is capable of subduing an adult human, it can be removed from a host's face by someone relatively easily albeit with the use of a knife, something that was virtually impossible with Xenomorph XX121 Facehuggers as their acid blood would have resulted in almost certain death for the host.
Planet 4 Facehuggers seem to have the ability to infect their host within seconds of attachment, which ironically makes their ability to keep a host alive and in a coma redundant as they would only need to remain attached long enough to implant the Chestburster. Even so, it's possible that the ability to infect a host within seconds of attachment may have developed as a last resort ability, as the only known case of this happening is while it was being forcibly removed. This is ability is not shared in its later counterparts as it become possible to remove the parasite before it could even implant its host, though at the cost of the host's life.
The acid blood of the Planet 4 versions seems to be slightly less potent as Lope only seemed to suffer superficial damage from it after the Facehugger was cut from his face and the knife used to cut it did not dissolve instantly, this is in contrast to the incident on the Nostromo where a slight cut on the parasite's digits spilled blood that ate through several decks of the vessel.
Subduing a host
This variant possibly subdues the host in the same way as its counterparts, through the use of a cynose-based paralytic and neuromuscular sedatives. However, this version does actually use strangulation to aid in subduing its victim as seen with Oram. Notably, this version is slower to coil its tail around a host's throat upon attachment whereas the XX121 version would usually coil its tail around its victim's throat even before attachment. The planet 4 variant remains as strong as the XX121 versions as neither Oram nor Lope could remove or even slightly dislodge the parasite on their own.
The Planet 4 Facehugger implants a host just like its Xenomorph XX121 cousins. However, whether the process is exactly the same or differs is unknown, but it has shown the capability to impregnate its host within seconds of attachment, making its behavior of staying attached and keeping the host unconscious seemingly redundant.
Unlike Xenomorph XX121 Facehuggers, this version was shown to be able be forcibly removed easily with the use of a knife and with minimum damage to the victim. However, due to its ability to implant its host within seconds of attachment, the removal can prove pointless in saving the victim.
Like with the other version, the hosts will wake up with seemingly little to no memory of what happened to them. However, since gestation occurs at a faster rate, hosts only have seconds to a minute before the Chestburster erupts. Oram, upon waking showed no signs of knowing what had happened to him.
The Planet 4 strain was intelligent enough to avoid and dodge gunfire, as well as to take cover. However, upon seeing another viable host, it immediately sprang from its cover and attacked. It was subsequently pulled off and killed, though it succeeded at infecting its host at the last moments before its removal.
- Once again the speed of the "Xenomorph" life-cyle is altered as the process from Facehugger to Chestburster is less than ten minutes, being more alike to the life-cycle seen in Alien vs. Predator.
- Also the scene where Lopé is attacked by the facehugger on Planet 4 has attracted much criticism from fans due to how it contradicts established lore.
- The novel explains the rapid speed of gestation and growth as due to David having accelerated the growth rate of all stages of the Planet 4 strain.
- The novel describes the Facehugger as being incredibly strong with neither Lope or Cole able to remove it even with their combined strength, which necessitated the use of a knife to cut it off Lope.
- The novel has Oram mention having dreamt about meeting god while he was unconscious. XX121 Facehuggers victims commonly seem to have strange dreams or nightmares.
- The Facehugger strongly resembles a species of arthropod David dubbed the "Carapace" in his ecological documentation of Planet 4.