Taxis response is to move towards or away from the stimulus. If the organism moves towards the stimulus the taxis is positive, while if it moves away the taxis is negative. For example, flagellate protozoans of the genus "Euglena" move towards a light source. This reaction or behaviour is called "positive phototaxis", since phototaxis refers to a response to light and the organism is moving towards the stimulus. Many types of taxis have been identified, including: Depending on the type of sensory organs present, a taxis can be classified as a "klinotaxis", where an organism continuously samples the environment to determine
Largest organisms March 2014 in a soil sample collected from a riverbank in Siberia. Prior to this discovery, the largest virus was the peculiar virus genus "Pandoravirus", which have a size of approximately 1 micrometer and whose genome contains 1,900,000 to 2,500,000 base pairs of DNA. Both these viruses infect amoebas specifically. Largest organisms The largest organisms now found on Earth can be determined according to various aspects of an organism's size, such as: mass, volume, area, length, height, or even genome size. Some organisms group together to form a superorganism (such as ants or bees), but such are not classed as