The zerg as a whole are extremely tough, tenacious, and deadly. Their natural armor and weaponry is formidable in nature.  The zerg are extremely resistant to poisons, toxins and alchemy,but their nature still renders them vulnerable to magic. All zerg are capable of operating in a variety of environments, and some can operate in voids. Most zerg are not adapted for multiplane travel by themselves, but are carried by larger zerg such as leviathans. 

Zerg must eat and rest, but do not require extended hours of sleep and have no set periods of inactivity. Left unchecked, zerg multiply at an alarming rate. Zerg do not die of old age.

Most zerg ground types are also capable of burrowing and digging through virtually any surface, using groups of tiny muscles that vibrate at a low frequency and grind dirt and stone along their way, allowing them to "swim through the ground". This ability made them extremely deadly in ambush situations, as many have suffered losses when suddenly being surrounded by a mass of zerg. Zerg also tend to travel underground to attack enemies by surfacing a nydus worm.

Zerg possess remarkable regenerative capabilities. Under normal circumstances, zerg may regenerate indefinitely.  Given time, even a gravely wounded zerg will return to full health. Thus, a zerg colony remains viable if even one creature or structure survives. Few zerg survive for more than a few minutes in a given battle, but those that do evolve during the battle itself, becoming more powerful every hour. The zerg constantly study their enemies and adapt accordingly.

Zerg structures are essentially giant organs and draw sustenance from creep, a thick slimy mucous-like substance that integrates a colony's structures as one being. The creep is actually a living extension of the structures that rest upon it and so is connected to the hive mind as well.  Unless cloaked by magic or psionics any zerg or zerg structure upon the creep can sense other creatures presence within 100'. 

The zerg like to pit themselves against harsh climates, using a planes harsh conditions to further their own evolution. In regards to assimilating other species, the zerg were initially very selective, assimilating only strong species at the top of their food chains and eradicating 'lesser species' lest they corrupt the purity of the zerg. However lately it seems the zerg are willing to assimilate any material they come across. Zerg can not infect magical and psionic creatures unless through psionic power or spell. These only create hybrids. 

Some Zerg have psionic abilities and all zerg are psionically tuned to the hive mind which offers them resistances against psionic and magical mind effects. Though Zerg do not possess the ability to use magic or care to they do understand it. They know to look for spell casters to target them. As a group they also react intelligently to attacks and are adept at tactical combat. On an individual basis, though, the zerg seem to be hardly more than savage animals with little or no concern for self-preservation. The amount of control exerted over a zerg force also impacts on their intelligence. Without this control, the zerg will become little more than animals, attacking everything on sight, at times, even their own kind. These zerg are referred to as feral zerg and can generally only operate at the lowest level. Zerg have the ability to sense psionics and, being sensitive to it, often respond to it and seek it out. A Zerg can be severed from the hive if it enters a psionic dead zone or is somehow dampened psionicly. At times they have even been able to be controlled for short periods of time. However the hive mind is much more powerful link and seems to overide any other psionic or magical control.