Taxis

Definition

A directed, innate movement of an organism toward or away from a stimulus, distinguished from undirected kinesis by its goal-oriented nature. The direction of movement is specified by the stimulus gradient: positive taxis moves toward the stimulus, negative taxis moves away. In arthropods, taxes mediate critical behaviors including host-seeking, predator avoidance, and microhabitat selection.

Etymology

Greek taxis, arrangement or ordering.

Example

Female mosquitoes exhibit positive anemotaxis, flying upwind in response to carbon dioxide and skin odor plumes to locate hosts; woodlice show negative phototaxis, retreating from light to seek humid refuges under bark or stones.

Synonyms

• directed orientation
• tropotaxis (when comparing bilateral stimulus comparison)
• telotaxis (when orienting to a single source)

Related Terms

• Kinesis
• anemotaxis
• Chemotaxis
• Phototaxis
• Thermotaxis
• geotaxis
• hygrotaxis
• tropism

Usage Notes

Taxis is directional movement; contrast with kinesis, which is non-directional change in activity rate. Compound forms (chemotaxis, phototaxis, etc.) specify the stimulus modality. Some specialists restrict 'taxis' to animals and 'tropism' to plants, though usage overlaps in invertebrate literature. The plural 'taxes' is standard in scientific writing; 'taxis' as both singular and plural is increasingly common but less precise.