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Movement of a motile organism using the earth's gravity for orientation.

ge′o·tac′tic (-tĭk) adj.
ge′o·tac′ti·cal·ly adv.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biology) movement of an organism in response to the stimulus of gravity
ˌgeoˈtactic, ˌgeoˈtactical adj
ˌgeoˈtactically adv
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌdʒi oʊˈtæk sɪs)

oriented movement of a motile organism toward or away from a gravitational force.
ge`o•tac′tic (-tɪk) adj.
ge`o•tac′ti•cal•ly, adv.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


the movement of an organism in response to the force of gravity.
See also: Gravity, Motion
-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.
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References in periodicals archive ?
The acanthocephalan parasite Polymorphic minutes alters the geotactic and clinging behaviours of two sympatric amphipod hosts: the native Gammarus pulex and the invasive Gommants roeseli.
The oyster's preferential attachment is also not a negative phototrophic behavior, but the larvae may be negatively geotactic: a possible evolutionary adaptation to reduce exposure to direct sunlight and decrease thermal stress to the future recruit (Hopkins 1935).
While remaining habitat was upstream, it moved down the canyon in a positively geotactic manner and remained oriented in the stream channel even when climbing over and around obstructions such as cobbles and woody debris.
Specifically, we observe that adult flies that are heterozygous mutant for genes within this genomic interval, exhibit deficits in locomotion, geotactic behaviors and the righting reflex.
Emerging adults exhibit a negative geotactic response, rising up in the cage to a boll-weevil trap where they can be easily removed and counted.
fimbriatus was both positively phototaxic and negatively geotactic and was aware that Dolomedes preferred damp habitats.
Divergent selection for geotactic response and evolution of reproductive isolation in sympatric and allopatric populations of houseflies.
Instead, deflections of the mechanoresponsive pacemaker balancer cilia by the statolith have been shown to mediate geotactic behavior (4, 14-16).