T'au Empire - T'au Anatomy and Physiology: The T'au's physiology is closely tied to their society, with the T'au of each caste effectively being a subspecies of the larger T'au race. This was initially a result of adaptation and evolution to suit the different environments each group of the proto-T'au species found themselves in on their homeworld of T'au, although interbreeding between the castes was later forbidden by the Ethereals.The T'au are humanoid in shape, although they have hoofed feet and four-digit hands (three fingers and one thumb). Their skin is grey-blue (although this can vary in pigmentation between T'au septs and colony worlds), rough in texture, leathery, and exudes almost no moisture. Their faces are flat, wide around the eyes, with an "I"-shaped slit running from the center of the forehead to where a Human's nose would be.T'au vision is considered slightly superior to that of Humans -- their visual spectrum extends a little more into the ultraviolet and infrared wavelengths. However their pupils do not dilate, giving poorer depth perception and providing slower vision focusing reflexes than Humans, particularly in low light conditions. The olfactory organs of a T'au are inside the mouth.Physical strength and size varies between the T'au castes with the Fire Caste being the strongest of their kind, roughly the size and slightly weaker than an average baseline Human because the T'au homeworld has gravity slightly weaker than that of Terra.Only two female T'au have ever been illustrated. The first, Commander Shadowsun, appeared to have a more Human face than male T'au; being smoother and sleeker with larger eyes, a nose-like facial feature and a "Y" shaped facial slit. It is not known, however, whether Shadowsun is representative of all female T'au. The second known T'au female, the subject of an Imperial dissection by the magi of the Adeptus Mechanicus, had the facial characteristics of a male T'au.The T'au do not possess psykers and as a result have little knowledge of the Immaterium beyond its existence. This gives them some level of resistance to Warp-based powers affecting the mind, but it offers little, if any, protection against physically-manifested offensive psychic powers. This is because the T'au have virtually no psychic presence in the Warp. To a Daemon or any psykers possessed of the witchsight, they appear as a shifting will-o-the-wisp rather than the burning fire that represents a Human's soul. As such, T'au can never possess or develop psychic powers.The T'au are largely unaware of the perils of the Immaterium and for this reason have conducted research into the nature of the Warp on Medusa V, however, the conclusion was reached that further research was unfeasible, and that "the Warp is no place for the Greater Good and is best left to those foolhardy races who cannot pull back from that terrible realm."Ethereal Caste members also have a diamond-shaped bony ridge on their head. It is believed by Imperial scholars that through this organ the Ethereals exert a pheromone-based or latent psychic control over the other T'au castes to keep them focused on the Greater Good, but this is mere speculation, and no evidence of this has yet been found.Due to their notable absence of psychic ability, the T'au have no equivalent to the Navigators of the Imperium, forcing them to travel at sublight relativistic speeds. Their interstellar vessels therefore take much longer than Imperial vessels to traverse the vast distances between the stars, which is one reason their empire has expanded relatively slowly over the centuries.T'au warriors receive only limited training in the arts of close combat, usually depending on Kroot mercenaries to fight in the horrible melees so common in 41st Millennium battles. However, due to the T'au's superior range of vision in the electromagnetic spectrum and a predilection for patience, the T'au have proven themselves to be extremely efficient sharpshooters with the ranged plasma weapons and railguns they primarily rely upon.The T'au tend to look upon other intelligent species as backwards or misguided. Before the commencement of hostilities they almost always try to reason with their opponents and establish some kind of agreement that will make the use of military force unnecessary. Noted exceptions to this policy are T'au battles with the Orks, Tyranids and the forces of Chaos, with whom the T'au have little to no diplomatic relations. This is due to the fact that the T'au see no way to reason with them, and do not want them in their empire.