Kroot - Anatomy and Physiology: The Kroot originated on the world of Pech and, though their anatomy is humanoid, there is evidence to suggest that the roots of their evolution likely lie with that world's avian analogues. Kroot retain vestigial beaks and have a light, almost hollow bone structure, with four digits on each hand and foot.Kroot skin is rough with small, barbed spines, similar to the elongated quills on their heads, protruding from various locations on their flesh. Skin pigmentation ranges from earthy brown colours and dappled greens to vibrant oranges and everything in between. Depending on the feeding directions of the Kroot Shapers, the colouration of each kindred can vary quite considerably.It is also common for Kroot from each kindred to have particular tribal markings painted onto their skin. Kroot mature quickly, with their most rapid period of growth occurring in the first ten Terran years of their lives. By the age of twelve Terran years Kroot are considered adults, and it is not unknown for Kroot to live to over a hundred Terran years old, their skin becoming increasingly pitted and leathery in their last few years of life.Kroot are tall, and their bodies have a wiriness to them that appears deceptively fragile. In actuality, Kroot musculature is extremely powerful and composed of dense fibre spindles with a greater power‑to‑mass ratio than is found in Humans. Swift muscle contractions create a whiplash effect, allowing the Kroot to deliver powerful blows with great rapidity.The Kroot tend to move on the ground with a bounding, hopping gait, but in dense forests, they can spring from tree to tree at great speed. The Kroot favour primitive garb: harnesses worked from the hides of animals and adorned with bones, handcrafted amulets and circlets.The limited specimens that have been made available for study by Imperial savants and the Magos Biologis of the Adeptus Mechanicus have possessed brains composed of a front and rear hemisphere. It appears that the larger frontal hemisphere controls the functions of logic, reasoning and memory while the rear, less developed hemisphere is more attuned to imagination and creativity.If this is indeed the case, it would go some way to explaining the pragmatic approach to life of the Kroot and their current technological stagnation.The Kroot head is crowned with a great mass of tough, flexible quills that appear to be a part of the Kroot's sensory apparatus. These quills contain what seem to be ganglia running from the frontal lobes of the alien's brain and, in this position, would be extremely efficient at receiving and interpreting information on the surrounding environment.The olfactory cavity within the Kroot skull is also enlarged, with multiple sense organs within both it and the mouth. Their eyes are without pupils and generally a milky white.It is likely that they are able to see further into the infrared end of the spectrum and can sense the body heat generated by their prey. Therefore, the Kroot make excellent trackers and would be extremely difficult to sneak up on.The Kroot generate little in the way of waste, as their bodies excrete metabolic waste in the form of a pungent, oily sweat that has a variety of properties, depending on what the Kroot has consumed.The most apparent benefits are that this sweat appears to be heat-retardant to a degree, has antibiotic properties and can cause a poorly-aimed blow to slide clear. It is suspected that the Kroot can alter the properties of this secretion in order to leave pheromone trails, mark territories, provide warnings to their fellow Kroot and even communicate with one another through scent.This may also be some form of biochemical control that extends to lower life forms such as other avians and animals, as there is evidence to suggest that the Kroot employ empathic pheromones to prevent such creatures from being startled by them and giving away their position in battle.Combined with this method of communication, the Kroot can learn new languages at an astounding rate, matching posture and tone to the sound of foreign words in order to discern their meaning. Their own verbal communication is a mixture of clicks and whistles, possibly reinforced by these pheromone excretions.