A humanoid is an organic or mechanical being similar in overall form to a Human, the most common sentient species in the galaxy. The term is less specific than Near-Human, which generally implies common biological ancestry with Humans. Classification of a being as humanoid was not standardized or strict. Generally, it entailed having a basic anatomy or construction similar to Humans, that is, a central torso with a head on top, two arms symmetrically arranged on either side, and two legs symmetrically arranged below, providing an upright bipedal stance. Each arm ended in hands that had a variable number of fingers (used for grasping and moving objects), and each leg in feet (used for locomotion). A living humanoid's head had two eyes, a nose for breathing and smelling, and a mouth for nutrition and communication; a mechanical humanoid would not require respiration or nutrition, and would have two photoreceptors instead of eyes. Humanoid species generally had sparse hair, mainly concentrated on the head or face. A species with slight variations and deviations from this general arrangement could still be classified as humanoid. For example, Duros had no ears, nose, or hair; Twi'leks and Togruta featured headtails; and many non-humanoids had humanoid features. Wookiees, although seeming animalistic, could be called humanoids; they were also classified as anthropoids, a term referring to a species with simian features. Non-humanoid sentient species had distinctly nonhuman characteristics, such as tails, additional limbs (or even no limbs, as with the Slith), wings, additional heads (as the Cha'wen'hes), or invertebrate characteristics (as the Gree).