Taxi

Taxis (from the Greek τάξις - “order, structure, arrangement”) - in biology - a method of movement of organisms in which they move in space in a certain direction due to active interaction with the environment. An example of taxis is the movement of amoebas and other protozoa along the concentration gradient of a substance, for example, food or chemicals.

The term “taxis” was introduced into botany by the German botanist G. Treviranus (1820), who defined taxis as “a movement that occurs in a certain order and direction, caused by external influence.”

A distinction is made between positive taxis, when organisms move towards the source of irritation, and negative taxis, when they move away from it. Negative taxis is characteristic, for example, of amoebas that tend to escape from light.

In 1902, German zoologist Ernst Haeckel proposed the term "taxis" to combine different types of movements, including taxis. Later, taxis began to be understood not only as the movement of organisms as a whole, but also the movement of individual parts of the body, for example, bacterial flagella.

Taxis play an important role in the life of living organisms. They provide orientation in space, facilitate the search for food, partners for reproduction, help avoid danger, etc.

In addition, taxis can be used as a diagnostic feature when determining the type of organisms. For example, some species of amoebas have positive taxis to light, which makes them easy to distinguish from other species.