Spider Mastermind: not natural fauna
The Spider Mastermind was not found naturally occurring on the other side of The Portal. Several specimins were observed, however, in diverse areas in the portal environment.
The Spider Mastermind is the creation of an alien intelligence, surgically combining the disembodied head and torso section of a very large, unknown, possibly aquatic life-form with a platform containing 4 highly sophisticated, multi-segmented mechanical legs and a forward-facing high speed alien machine gun.
The Spider Mastermind uses almost identical technology and structure as the Arachnatron, except on a much larger scale. The legs and weapon are not directly controlled by the brain. The actual control of the legs and weapon is performed by a centrally-located alien computer-like unit which functions as a ganglion. The biological half of the unit can, through signals sent to the ganglion, cause five total activities to be performed by the legs and weapon: ambulate forward, stand in one location, stand braced and fire the weapon, pivot to the left, and pivot to the right. The computer-like ganglion functions as a controller for the mechanical legs and weapon. This ganglion controls the foot placement, leg movement, and maintains the unit's balance, utilizing a multitude of positional sensors within the mechanical legs and feet. Each foot has several appendages which function both as the support structure for that leg as well as containing sensory devices that relay information about the terrain angle.
The agility of the Spider Mastermind is more limited than that of the Arachnatron. It maintains a very wide stance between its feet, and this prevents it from moving through areas or past obsticles bounding an area smaller than around 20 ft (6.666 meters) in diameter.
It is believed that the organism the biological section of the Spider Mastermind is based upon is either meat-eating, omniverous, or a scavanger. Its teeth and mouth are built for tearing bites of food, not catching prey. A Spider Mastermind has never been observed to eat, so to date its means of sustanence is unverified.