Both normal 'crabs and baby 'crabs.
Yep, you saw all three stages of development on Xen.
Ahhh it’s threads like these that really seperate those with no attention span from those who know what they’re talking about. Non-canonical answers are not answers.
The Gravity Gun was developed by Eli and Kleiner in the 20 year span between Half-Life 1 and Half-Life 2, it was built for handling hazardous materials.
There is a combine teleport somewhere inside the citadel which is how Mossman and Eli arrived there in the first place, Mossman set the co-ordinates of the Nova Prospekt teleport to teleport them to the Citadel’s teleport instead of Kleiner’s. Mossman and Eli escaped the citadel this way too. Which is precisely why Eli is already back with Kleiner at the beginning of Episode 1.
It’s not confirmed, but most people agree that the mutated chest-cavity is used for feeding and possibly breathing, since the headcrab is obstructing the mouth and nose. Though, aparently they can still vocalise moans… which would imply that their airways are still intact.
After Mossman and Eli were teleported out of the citadel to Kleiners lab they probably teleported to white forest if there is a teleporter there. If not then they obviously took a train to white forest. We don’t know how much time passed between the explosion at the top of the citadel and when Gordon emerges from the rubble at ground zero. Probably a few hours.
Mossman had already left for the Arctic base at the start of Episode 1, after arriving at White Forest. She may have used a teleport or other form of transport such as helicopter.
Mossman’s message was intercepted by the combine somehow, possibly by another insider within the rebels and that’s why it was recieved by the citadel and not sent to Kleiner. Obviously the combine are equally interested by the Borealis. Alyx found it whilst downloading the combine transmission data.
It’s unknown what headcrabs normal diet consists of, but headcrabs are omnivorous as evidenced by Llamar who lives off a diet of watermelons. It’s unclear how headcrabs cause the mutations that they do. Headcrabs appear to be quite primitive and their behaviour seems purely instinctive. They do what they do to feed.
It’s not known if headcrabs were originally from Xen, but they certainly inhabited it. We don’t see the entirety of Xen, I have the feeling that Xen is much larger that what we see and that it’s stretched over a large interdimensional plane.
I’ve read several places (though I don’t know of an official Valve source offhand) that they escaped via Breen’s escape pod, not a teleporter. What reasons do you have for thinking they escaped via a teleporter?
Because they got there via teleporter.
I’ll tell you the same thing I told my friend when he was bitching about why they added Mark and Execute in Splinter Cell: Conviction:
“Cuz’ it looks fucking awesome!”
children of hl2 will never know the truth…
¦)
also, first two points refers to hl2 either, therefore the thread sould have been named “half-life 2 facts that need explaining” ,]
Rofl, epic way of putting it!
If I recall, all the headcrabs stopped spawning once you killed the Gonarch. Also, the Nihilanth’s “Done, what have you done?” seems to imply that by killing the Gonarch and the Headcrabs, we’ve destroyed Xen’s eco system.
Or more simply you’ve killed his pet or headcrab factory.
Lol! I just noticed the siggy for Mangled*. haha… er… hey wait. Wut is this? Mangled* are you Badsmed? =\
Well, it is possible that Gonarch’s state was the last stage in a headcrab’s evolution if they don’t attach to anything. But that’s just a possible theory i have, don’t have anything to prove it with 
yeah, i wonder, there is the gonome, but don’t thinks thats officially canon. I wonder if the host body after eating enough eventually turns in to the big testicle and the gonarch grows from there?
Exactly, no real explanation was ever given on that. So it’s still a possibility that there’s a big headcrab running around there 
No, I clocked it on Steam forums and found it amusing to put it here. :3
I said “as a series.” I didn’t use any Half-Life 1 examples because I couldn’t think of any. And with ratio of people actually asking questions compared to the number of people making up stupid answers, i’d say it’s time for a lock.