As stated, Queens are created through royal facehuggers which produce Praetorians, or immature Queens. When a Queen dies or abandons a hive, a Praetorian may fully develop into a new Queen and take her mother's place. Whereas normal embryos adopt characteristics from their host, the royal facehugger's does not. The royal facehugger carries within it the Royal Jelly Line, which is a genetic code passed down from the Queen Xenomorph to her chosen offspring. The embryo is more or less a genetic copy of its mother and as such will not adopt the characteristics of the host, but will retain the physical characteristics of the Xenomorph Queen. Regardless of host, the Praetorian will appear nearly exactly the same as its mother when it fully develops into a new Queen. Because of this, it's often speculated that the Queen is the only "pure blooded" Xenomorph variety. In Aliens vs. Predator: Requiem, a Drone Headbites an already dead human body. It is not known why it did this, but is presumed (or suggested) to have been feeding on the corpse. If this is the case, it would also suggest that Xenomorphs swallow their food through their second mouth.

Xenomorphs are conscious of the effects of their acidic blood, and will use it to their advantage - to break out of Human-constructed confinement, or as a weapon. They show some military tactics (such as retreating when overwhelmed), and can find ways to get around certain problems (such as pushing the red button to freeze a soldier in liquid nitrogen in the afore-mentioned incident). They know that the darkness is their ally, and break lights to create cover. Jody Duncan. The Winston Effect: The Art and History of Stan Winston Studio, p. 85 ( 2006), Titan Books. As arguably the Xenomorph's signature killing move, the Headbite has often been an integral part of gameplay in the various video games featuring the creature.In the 2010 video game Aliens vs. Predator, Headbiting is included in some of the game's stealth/trophy kill animations, and as such can be used both by the player and against them by others (in competitive multiplayer modes). When playing as an Alien, it is also possible for the player to Headbite the corpses of people they have killed (so long as they were not also initially killed with a Headbite), and doing so will recover all lost health. Besides their guard duties, Praetorians may also act as the "princesses", or immature Queens of the hive, who can be promoted to Queens. [14] The Xenomorph known as "Number Six" started out as a Warrior and demonstrated the ability to mature into a Praetorian and later a Queen. [18] This rapid alteration is another evolutionary trait of the Xenomorph to ensure its very survival as a species. The Xenomorph Queen can lay specialized eggs that are bigger (like Queen egg cells in bees which are bigger than Drone cells), that upon hatching can carry on the species through making other hives after the new Xenomorph morphs/cocoons into a Queen. Some Xenomorphs have tails that are roughly the same length as the rest of their bodies, equipped with a small, almost surgical stinger-like barb on the end. This stinger can be, and has been, used to perforate victims, and may turn loose from the tail and remain lodged in the victim's body, not unlike a bee stinger. Conversely, other specimens have tails that are considerably longer, and armed with a large, knife-like blade at the tip and sometimes with ridges of spikes right before the blade, which may aid in swimming. Another is the Predalien's inherited tendency to skin victims. This was probably dropped because skinning victims isn't something that comes instinctively to Predators, but rather a learned behavior. It is somewhat unlikely that this fluid carries oxygen for a few reasons: the first being that the Xenomorph has been known to survive in vacuums such as space (for short periods of time, at least). The second being that Bishop mentions that the fluid loses its acidity shortly after the creature's death due to oxidation [10]. On the other hand, this is plausibly unimportant as oxidation is a term in chemistry used for the loss of electrons rather than a reaction with oxygen. All acids are oxidized no matter what they react with, therefore this has no bearing on blood carrying oxygen.

Originally, the Xenomorph's tail was roughly the length of the rest of its body, with a small, almost surgical stinger-like barb on the end; but from Alien³ onward, the tail has extended in length and features a large, knife-like blade at the tip. In Alien: Resurrection and Alien vs. Predator, the tails have also supported a ridge of spikes right before the blade. This was introduced in Alien: Resurrection to help them swim convincingly, and was left intact in Alien vs. Predator. The tail itself is shown to be of incredible length during Alien vs Predator, measuring almost its full body length.Some varying reports of Praetorians with massive shield-like growths on their forearms have been seen. Egg-laying Alien queens possess an immense ovipositor attached to their lower torso, similar to a queen termite's. Like some insect queens, there appears to be no need for an Alien queen's eggs to be fertilized. [11] [25] When attached to her ovipositor, the queen is supported by a "biomechanical throne" [29] that consists of a lattice of struts resembling massive insect legs. The spines might be used as a defense mechanism, to repel enemies that try to sneak up on them from behind or above. That said, the alien queen, at least, appears to be able to see what Ripley is doing at a distance, e.g. when she threatens the eggs with the flamethrower. It's possible she has a rudimentary optical sense combined with an IR/heat-sensing ability like pit vipers: