Xonian Wildlife
Ah... the wildlife of Xen.. so much to know.. So much to tell.. Lets at first get clear that I won't provide the actual sounds cause YOU got em.. If you want to know listen ingame or check the pakfiles. :) Also i won't show hte Xonians on the timeframe YOU see em but on the timeframe THEY exist. Just letting ya know.
Baby-HeadCrab

Ah.. the little buggers. Yes.. hold your horses... this pic is idioticly enlarged.. There actually not bigger then a snark. Thats the small critter you can throw ingame as a weapon.
These BCrabs still have a eggsack, are partially transparent and weak... There so transparent cause they need to cloak themselves since there newborn and weak... There main weapon is a leap... they hit you with there claws since they don't have jaws yet.. after all... they got there eggsag still.
However don't think you got a easy job with those... Sure.. they die fast but are hard to hit, come in groups and mommy aint far...
HeadCrab
Ah.. little buggers aswell and alot more dangerous then the bCrabs... usually found in groups or alone.
They make distinguish sounds which someone will soon here while closing onto them. Now remember to PAY ATTENTION while you hear em.. They CAN bite, quite painfull, and when you lack a HEV suit its sudden death. Also they can still leap and slash with there claws... remind again.. they LEAP.. So don't think that they are far enought... its to short soon.
Given the low grav in Xen it is speculated to be a even more dangerous thread there. Speculating the bigger jump capability there.
I didn't discuss this with babys since thats 0% but the brains of Crabs.. do they have brains.. Simply put no. They got instincts.. good instincts but sure hell no brains. not much space for that in there little bodies. you notice there instincts soon.. they attack, kill, flee and even aim for the head... but they lack brains.. After all... they CAN leap without interruption.. they don't need pauses. yet when fleeing they chose to "run" (which is freaking slow) instead of leaping to safety.. Also they have been observed to walk towards you while taking bullets continuesly.. only leaping while in attack range.. So.. no brains.
Note... crabs do NOT have falldamage. They got eyes near there claws on the front.. no known noose or ears.
There one known natural enemy is the BullSquid..
Gonarch
Also known as Big Momma
Ow screwing hell.. the mommy.
Fears.. NOTHING. Now the darn critters somehow got to this size they outsize a bullsquid 3 to 1. (unlike in HCrab state where the Squid outsized them atleast 10 to 1) And with power its even of the charts.
The above weird glancing looking head is pure armor. YES.. thats right.. this thing grew itself a bioarmor on its body.. Its legs also have this powerfull defense mechanism. As you can see the legs changed there position to get the big body above ground. The top armor is stronger then the more black armor on its belly and on it wrists.. Yet.. it is still to strong to get through.
There is only one known week place in this strong Creature. The eggsack. Where it keeps it young. Since its not a critical organ you will probably need to pump ALOT of ammo into it before it finally gets frustrated enought. After alot of ammo waste you will kill it by shooting it but it will take long.
Because of its size, armor and also idiotic power the gonarch has no known natural enemies... Even the bullsquid can't handle a Creature 3 times its own size. The Gonarch has a long distance weapon aswell.. And quiet deadly. Its a kind of chemical capable of floating. It bites hard and fast.. yet still prefer this above its close range combat allways... Its claw attack is insane strong.
Mommy still lacks brains... She shall release her young when under attack to let them help fight.. (letting her little ones die while she was protecting them a sec ago) Also it can be lured in traps quiet easy. but hey.... with that armor and power noone needs brains.. yet the small number of em speculates that it takes pure luck to reach this level.. No doubt that the Bullsquids kill crabs for food AND to keep the gonarchs number down. Again.. there have been reports of gonarchs been lured under a Xen Tree, being smashed.. No brains... Also porbably no falldamage..
If posible AVOID.. yet mostly it lives in areas which ya gotta pass.