Taxis
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Locomotion response to external stimulus |
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A taxis ( ancient Greek τάξις táxis "order", "alignment") is a targeted orientation reaction of living beings , ie based on a stimulus or an environmental factor (e.g. temperature , concentration of a substance , illuminance ). Taxia occur in freely moving microorganisms, animals and plants.
In the context of the instinctive theory of classical comparative behavioral research (ethology), taxis also refer to the directed appetite behavior of an animal within a complex instinctual behavior . According to this theory, it is triggered by stimuli such as noises or movements, but only carried out if the willingness to act is also present.
Types of taxis
Positive and negative taxis
A distinction is made between responses directed towards the stimulus (positive taxis) and avoidance or startle reactions directed away from the stimulus (negative taxis), as well as movement directed towards the source of the stimulus (topotaxis) and a "startle reaction" (phobotaxis; e.g. flagellar-driven locomotion with tumbling - and running phases).
Even more precise classification:
- Telotaxis: the direct straight alignment of the sense organ on the stimulus.
- Menotaxis: the orientation at a certain angle to the stimulus.
- Tropotaxis: the symmetrical alignment to the stimulus, for which two spatially separate sensory organs are required on the living being. The alignment takes place at the same angle from both sensory organs.
- Mnemotaxis: the orientation based on memory (e.g. orientation based on the position of the sun or based on chemical substances).
Differentiation according to stimuli
- Aerotaxis : Orientation towards oxygen (a special form of chemotaxis or energy taxis)
- Anemotaxis : Orientation on the air flow
- Chemotaxis : Orientation based on chemical stimuli
- Energy taxis : orientation based on the intracellular energy level
- Galvanotaxis : Orientation on electrical fields
- Gravitaxis (formerly Geotaxis): Orientation towards gravity
- Hydrotaxis : Orientation on the soil or air humidity
- Clinotaxis : Orientation by comparing temporally offset information from a receptor / sensory organ
- Magnetotaxis : orientation in magnetic fields
- Osmotaxis : Orientation on an osmotic gradient
- Phonotaxis : orientation based on acoustic stimuli (including ultrasound)
- Phototaxis : orientation based on the brightness and color of the light (including infrared and UV radiation)
- Polarotaxis : Orientation on the polarization of light
- Rheotaxis : Orientation on the water flow
- Scototaxis : Orientation towards the dark
- Thermotaxis : Orientation based on heat stimuli
- Thigmotaxis : Orientation based on tactile stimuli
- Traumatotaxis : Orientation (of cell organelles) towards an injured cell
Examples
- Turning to light (positive phototaxis) and at the same time orientation to gravity (gravitaxis) in Euglena viridis , a photoautotrophic unicellular organism
- Orientation of bees and ants based on the position of the sun
- Turning towards prey due to chemical substances (chemotaxis) in back swimmers
- Alignment of the body axis to the prey, for example in toads
- Phonotaxis of the crickets : Females orient themselves according to the singing of the males
See also
Web links
Individual evidence
- ↑ Lutz Nover, Elmar W. Weiler: General and molecular botany . Georg Thieme Verlag, 2008, ISBN 3-13-152791-9 , p. 141 f .