Gravitaxis (or geotaxis[1]) is a form of taxis characterized by the directional movement of an organism in response to gravity.
However, gravitaxis can result also from a purely physical mechanism so that organs for sensing the direction of gravity are not necessary.
A positive taxis is one in which the organism or a cell gravitates towards the source of stimulation (attraction).
[4] The response of planktonic larvae of Lithodes aequispinus (king crab) to gravity is another example of gravitaxis.
[5] The term is coined from gravi- meaning gravity, and taxis or the movement of an organism in response to a stimulus.