Glossary, continued. 



STANDARD LENGTH— Distance from the tip of a 

 fishes snout or lips to the end of the last vertebrae at the 

 base of the caudal fin. 



STENOHALINE — Pertaining to organisms that are re- 

 stricted to a narrow range of salinities, in contrast to 

 EURYHALINE. 



STENOPHAGOUS- 

 food items. 



-Subsisting on a limited variety of 



STENOTHERMAL — Pertaining to organisms that are 

 restricted to a narrow range of temperatures, in con- 

 trast to EURYTHERMAL. 



STOCK — A related group orsubpopulation. See POPU- 

 LATION and SUBPOPULATION. 



STOMATOPODA — An order of highly specialized car- 

 nivorous crustaceans commonly referred to as mantis 

 shrimp. 



SUBADULTS— Maturing individuals that are not yet 

 sexually mature. 



SUBLITTORAL — The benthic zone along a coast or 

 lake that extends from mean low tide to depths of about 

 200 m. 



SUBPOPULATION— A breeding unit (deme) of a larger 

 population. These units may differ little genetically and 

 taxonomically. See SUBSPECIES. Subpopulations 

 may intergrade with some interbreeding, or they may 

 occupy a common seasonal range prior to the mating 

 season. The units may have different reproduction 

 times and be separated spatially or temporally. See 

 RACE, STOCK, and POPULATION. 



SUBSPECIES — A taxonomic class assigned to popu- 

 lations and/orsubpopulations when interbreeding (gene 

 flow) between populations is limited, and there are 

 significant differences in some combination of charac- 

 teristics between subspecies (e.g., appearance, 

 anatomy, ecology, physiology, and behavior). While 

 successful interbreeding can occur when the groups 

 are in contact, under natural conditions reproductive 

 isolation is complete and the groups are considered 

 distinct. Classification of such groups is based on the 

 comparative study and judgement of phylogenists. A 

 second epithet for each subspecies is added to the 

 binomial for the species (e.g., Oncorhynchus clarki 

 clarki). See SPECIES, POPULATION, and SUB- 

 POPULATION. 



SUBTIDAL— See SUBLITTORAL. 



SUPRALITTORAL— The splash zone of land (adja- 

 cent to the sea) that is above the mean high tide level. 



SUSPENSION FEEDER— An animal that feeds di- 

 rectly or by filtration on minute organisms and organic 

 debris that is suspended in the water column. 



SYMBIOSIS— The relationship between two interact- 

 ing organisms that is positive, negative, or neutral in its 

 effects on each species. See COMPETITION, MUTU- 

 ALISM, PARASITISM, and PREDATION. 



SYMPATRIC — Species inhabiting the same or over- 

 lapping geographic areas. 



TAXONOMY — A system of describing, naming, and 

 classifying animals and plants into related groups 

 based on common features (e.g., structure, embryol- 

 ogy, and biochemistry). 



TEMPORAL— Pertaining to time. Used to describe 

 organism activities, developmental stages, and distri- 

 butions as they relate to daily, seasonal, or geologic 

 time periods. 



TERRITORY — An area occupied and used by an indi- 

 vidual, pair, or larger social group, and from which 

 other individuals or groups of the species are excluded, 

 often with the aid of auditory, olfactory, and visual 

 signals, threat displays, and outright combat. 



TEST — A rigid calcareous exoskeleton produced by 

 some echinoderms in the class Echinoidea (e.g., sea 

 urchins and sand dollars). 



THERMOCLINE — A relatively narrow boundary layer 

 of water where temperature decreases rapidly with 

 depth. Little water or solute exchange occurs across 

 the thermocline, which is maintained by solar heating 

 of the upper water layers. 



TIDAL FRESH ZONE— The portion of an estuary with 

 annual depth-averaged salinities of less than 0.5 parts 

 per thousand (%o). 



TINTINNIDAE — A family of ciliated protozoans. 



TOTAL LENGTH— Length of a fish measured as a 

 straight line from the anterior end of the snout to the 

 distal end of the caudal fin. 



TREMATODA — A class of parasitic flatworms of the 

 phylum Platyhelminthes. Trematodes have one or 

 more muscular, external suckers and are also known 

 as flukes. 



352 



