Genestealer - Genestealer Anatomy and Physiology: Genestealers, like virtually all Tyranid organisms, are characterised by their six limbs and resilient, armoured exoskeletal carapace. They are bipedal and able to move with lightning speed on their reverse-jointed, clawed lower limbs. The upper sets of limbs are distinctly different, the foremost pair ending in razor-sharp claws capable of slicing even through Tactical Dreadnought Armour (ref. Battle of Macragge. Ultramarines 1st Company.qv).Their secondary limbs are typically shaped like gnarled hands, allowing them to manipulate objects, climb and even operate simple devices such as touch-panels. The number of digits differs depending on the parent organism. Despite their dexterity, these secondary limbs are still more than capable of ripping a limb from its socket. The thickly-muscled tail appears to be vestigial, although it could aid the balance and agility shown by all variations of the species. it seems to allow the creature to race at full speed across piles of rubble and tangled scrap to close upon its enemies.Isolated broods of this Tyranid bioform are typified by a blue-indigo coloration. Such beasts have been encountered not only on numerous space hulks, notably the Sin of Damnation, but also upon the moons of Ymgarl, once thought home to a tentacle-mawed variation of the xenoform. This strain is possibly specifically nomadic; bio-engineered by the Hive Mind purely to infect new hosts.Where a Genestealer is part of a larger hive fleet, it will instead bear the same colouration as the rest of the Tyranid bioforms in its fleet. Specimens have been reported ranging from bone-white to jet black. Such bioforms communicate via telepathy, enabling their broods to operate independently.Hive fleet broods are often centred around an alpha predator sometimes mistaken for a Genestealer Patriarch, though this creature is more accurately termed a "Broodlord." This beast is not empowered by the psychic energies of a Genestealer Cult's "Broodmind," but by a single brood of Genestealers. If divorced from the greater swarm of a Tyranid invasion, hive fleet Genestealers can evolve into a purestrain form, their life cycle optimised to infect new hosts once new feeding grounds are viable.A Genestealer's head is characteristically bulbous and houses a disproportionately large brain for such a single-minded creature. Its jaws are lined with viciously sharp teeth, all designed for ripping and tearing; like other Tyranids they possess only incisors and no molars.Their carapace, along with the density of their internal skeleton, typically thickens with body mass; a Genestealer whose host was Orkoid will typically be tougher than one born of Aeldari gene-stock. Underneath this is the fibrous muscular sheath that can be compared to standard Imperial Flak Armour in terms of durability. These layers provide a considerable degree of protection; combined with their naturally tough physique it is possible for a Genestealer to charge headlong through a volley of lasgun fire and survive.As with other Tyranid organisms, Genestealers typically have an insectoid-like, open circulatory system with haemolymph flooding the intercellular spaces. This system is host to unnumbered phage cells, believed by the magi biologis of the New Hallefuss research facility to be digestive systems. These allow them to feed on the nutrient-rich end product of a Tyranid invasion. Closer investigation shows the phage cells to have a dual purpose, acting in a manner similar to fibrinogens in the Human bloodstream and clotting the liquids that seep from any wounds that the Genestealer has suffered (ref.MBfl277.anticoagulant.hellfire.qv).Another physiological anomaly that Genestealers display is the redundant respiratory and circulatory systems inherited from their host species. Furthermore, they exhibit vestigial digestive systems. Some specimens even have complete stomachs, although these are superfluous given the efficiency of the phage cell. These expendable physiological systems allow the Genestealer to sustain considerable non-lethal damage and still function. It is widely known by Imperial forces that those coming into conflict with Genestealers should direct their fire towards the thorax and abdomen of the beasts, as even with several extremities missing they are still highly dangerous opponents.Thanks to the capture of live Tyranid specimens by the Draco Legion Chapter of the Adeptus Astartes, it is known that Genestealers are able to feel pain and react adversely to its application, either becoming incredibly aggressive or cowed into temporary submission. Genestealers have a tremendous tolerance for cold, allowing them to survive in the void of deep space, hidden within the bowels of the space hulks they typically infest. They are even able to survive in a vacuum for a short space of time.To truly exploit the space detritus it inhabits, a Genestealer has great longevity and also the ability to endure long periods without nourishment. A Genestealer may also enter a torpid state at will, lowering its metabolic rate dramatically, therefore allowing them to survive long periods of inactivity and hardship until new prey enters their lair.