How do unicellular organisms navigate their environment?

Despite the absence of organs and tissues, unicellular organisms can navigate in the environment due to the presence of special organelles that perceive environmental factors and influence movement. This movement is called taxis. For example, phototaxis is movement to an illuminated place (light perceives stigma – a light-sensitive eye in autotrophs), chemotaxis is movement to certain substances. Also, orientation is influenced by the concentration of substances in the environment, this is associated with osmosis and diffusion. At a high concentration (hypertonic), the cell will tend to the part of the environment where the concentration outside the cell will be equal to the concentration inside (isotonic environment).