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GLOSSARY 



saprophytic pertaining to any organism, generally called 

 a saprophyte, that feeds upon dead organisms or 

 decaying organic materials. 



satellite a heavenly body revolving about another; gen- 

 erally restricted to a body revolving about a planet. 



savanna an area that is predominantly continuous grass- 

 land but has scattered shrubs and/or trees. 



scavenger an animal that feeds upon animal wastes and 

 dead organisms that are not killed but are found dead. 



schizocoel a coelom originating from a split in the meso- 

 derm; diagnostic of the Schizocoela, Mollusca, Sipun- 

 culoidea, Echiuroidea, Annelida, and Arthropoda, but 

 also found in the Lophophorata. 



scolex the "head," or anterior attachment organ of a 

 tapeworm. 



scrub an area or dense growth of low, perhaps stunted, 

 shrubs and/or trees, e.g., chaparral. 



seaweed any of the large marine algae. 



secondary that which follows any primary natural history 

 feature. 



secretion a useful, generally liquid, product of a cell or 

 gland, or the process of forming the product. 



sediments all deposits, usually by water, of the products of 

 erosion; either particles or cemented particles are 

 sedimentary rocks. 



seed a plant reproductive structure composed of a ripened 

 ovule. 



segmentation when restricted, metamerism. 



self a half-crescent-shaped structure resembling half of a 

 barchane and formed by two prevailing directions of 

 the wind. 



selection unless otherwise designated, natural selection. 



serol pertaining to developmental and unstable, rather 

 than climax, communities. 



sere a single cycle of community changes from initial in- 

 vasion of life to the climax; a unit of succession. 



sessile a sedentary and attached organism in contrast to a 

 free-living one; any part of an organism continuous 

 with another part and usually due to the absence of a 

 connecting (often stemlike) part. 



seta a bristle, especially as in annelids. 



sex cell a gamete. 



sexual pertaining to reproduction involving the fusion of 

 nuclei (fertilization) of two unlike, parental gametes. 



shoot a stem or young stem; generally a stem with leaves. 



sill a flat body of igneous rock formed by the solidifica- 

 tion of magma injected between layers of older rock. 



simple pertaining to an organism or a part that is uncom- 

 plicated by special structure, function, or behavior and 

 most resembling attributes of ancient life. 



social dominance an established group behavior pattern in 

 which one or more individuals by previous combat or 

 threat control or subject others in the group. 



social group any aggregation of two or more members of 

 the same species; often mentioned as a colony. 



society a social group displaying cooperation within it- 

 self. 



soil a mixture of organic material and inorganic particles 

 (rocks and minerals) existing in a relatively thin layer 

 over much of the earth; a soil horizon is a layer within 

 a soil; a soil profile is a vertical sample, including soil 

 but extending from the surface to parent material. 



solid the state of matter in which movement of component 

 parts is restricted to vibration about fixed average 

 positions; in contrast to a gas or liquid, it has fixed 

 shape and offers resistance to an applied force. 



solitary organism any member of a species that normally is 

 not found in groups of its species; a species not forming 

 social groups. 



solstice either of the two points in the earth's orbit when 

 the sun's rays become perpendicular to the northern- 

 most (June 21) or southernmost (December 21) pos- 

 sible points from the equator. 



solute a substance broken up into fine particles (dissolved) 

 by a solvent, e.g., salt in water. 



solution any intimate, homogeneous mixture of two or 

 more substances, one usually being a liquid, that can 

 be separated by simple processes. 



solvent the component of a solution that is in excess, 

 provides the characteristic state of the solution, and 

 causes dissolution of the solute. 



somite a body unit in metamerism. 



sorus a cluster of sporangia in ferns; sometimes applied 

 to any mass of spores. 



specialization an adaptation that is primarily due to 

 heredity and is hardly modified by the environment. 



specialized pertaining to an organism or any part of an 

 organism that is complex in structure, function, or 

 behavior; generally applied to presumably late devel- 

 opments in the evolution of life and/or complex fea- 

 tures whose use is restricted to one or a few environ- 

 ments. 



speciotion the process of species formation. 



species a taxon below the genus; a kind of organism; 

 generally defined in terms of lacking or very limited 

 geneexchange with other such groups; also, a category 

 applied to various nonliving things. 



sperm a male gamete; a mature and functional male sex 

 cell; the male fluid containing male gametes. 



spermatophyte any plant forming true seeds; sometimes 

 considered a major taxon of plants in contrast to 

 pteridophyte; most likely not a natural group. 



spicule a needlelike body. 



spiracle an external respiratory aperture; in insects, the 

 external opening of the tracheae system; in cartilagi- 

 nous fishes, a modified gill slit or opening. 



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