- Taxis or tactic.
- Cyclosis movements.
- Amoeboid movements.
- Vibrational movements.
- Contractile movements.
When changes occur in the environment, cells can respond by moving to these environmental stimuli, a phenomenon called taxis or tactic. These stimuli can be chemical (chemotaxis) or light (phototaxis).
The chemotaxis causes changes in the direction or type of movement in response to the stimulus produced by a chemical. Can be:
- Positive. When the cell moves towards the area of highest concentration of a substance, such as nutrients.
- Negative. When the cell detects a toxic substance and moves to where there is less concentration of that substance.
The phototaxis is the ability of many photosynthetic cells (using light as an energy source) to move according to the light intensity where the wavelength is more suitable for photosynthesis.
It is carried out by cells that can change their shape and consists of the emission of pseudopods or cytoplasmic processes, which is why they are carried out by free cells without a rigid membrane, such as amoebae, myxomycetes, and leukocytes.
The displacement is achieved by changing different parts of the cytosol from the gel state to the sun state, and emitting the pseudopods.
There are several types of pseudopodia:
- Philopods: thin and spindle-shaped.
- Reticulopods: slender, long, and intertwined.
- Lobopods: short, thick and isolated.
Video: Amoeboid movements.
Video: Bacterial flagellum movement.
This movement consists of shortening and stretching of the cell due to the existence in the cytoplasm of contractile proteins. For example, muscle cells have fibrous proteins in the hyaloplasm that allow this movement.