S— Continued 



succession, allogenic— See allogenic succes- 



succession, autogenic— See autogenic suc- 

 cession. 



succession, autotrophic — See autotrophic 

 succession. 



succession, heterotrophic— See heterotro- 

 phic succession. 



succession, primary— See primary succes- 

 sion. 



succession, secondary— See secondary suc- 

 cession. 



supralittoral— The zone immediately 

 adjacent (landward) to the mean high 

 water level; commonly called the splash 

 zone. See also supratidal. 



supratidal— See supralittoral. 



symbiosis— A term referring to two species 

 living together. It may be a commensal, 

 mutual or parasitic relationship. 



synecology— The study of the ecology of 

 communities, associations or groups of 

 organisms living together, as opposed to 

 autecology. 



synergism— Total effect of all interactants 

 when acting together is greater than the 

 sum of interactants acting individually. 



__T-- 



temperature compensation— An organism's 

 compensatory reaction to changes in 

 temperature via physical change(s) or 

 change(s) in habit(s) which tend to favor 

 maintainence of a more nearly optimal 

 body temperature. 



terrestrial— Of or relating to the earth and 

 its inhabitants— as opposed to aquatic. 



territory— The area an animal lives in and 

 actively defends. 



thallophyte— A taxonomic grouping of sim- 

 ple plants which lack true stems, leaves 

 and roots (e.g., algae, fungi, etc.). 



thermocline— In vertically stratifical water, 

 the layer where there is a rapid change in 

 temperature from the overlying to the 

 underlying waters. 



thigmotaxis— The response and alignment 

 to touch or contact. 



tidal flat— Flat land areas which are covered 

 and uncovered by the rise and fall of the 

 tide. Vegetation, if present, consists of 

 rushes, grasses and other halophytes. 



tolerance— The relative capability of an 

 organism to endure or adapt to unfavor- 

 able environmental factors. 



tripton— Dead particulate matter suspended 

 in water; the nonliving part of the 

 seston. 



trophic levels— Levels of food production 

 and consumption beginning with the 

 primary level, the producers, and con- 

 tinuing up through the consumer levels, 

 the herbivores, omnivores and car- 

 nivores. 



trophism — A directed movement in re- 

 sponse to a stimulus. 



17 



