Sea (Coiilinuedl 

 zonation In, 365 

 plankton as basic link in food 



chains of, 351 

 salinity of: 

 adjustments of marine organisms 



to, compared with adjustments 



of fresh- water organisms, 354 

 and abundance of populations of 



organisms, 356 

 and pH, 354 

 approximation of, 354 

 as providing nutrition, 354-356 

 forces keeping up level of, 356 

 osmotic regulation in adjustment 



of organisms to, 357 

 variations in as dependent on 



inflow of fresh water, 354 

 similarity of concentration of ions 



in to body fluids of some inver- 

 tebrates and origin of life, 354 

 southern hemisphere composed 



largely of, 151 

 substratum of: 

 and adjustments of animals to 



pounding action of waves, 352 

 conditions for occurrence of as 



sandy beach, 352 

 pelagic deposits in, 352-353 

 red clay in, 353 

 seashore burrowing animals in, 



352 

 terrigenous deposits in, 353 

 succession from to fresh water: 

 and brackish water species, 36H 

 and development of mangroves 



in tropical regions, 368 

 and fish migrating between fresh 



and salt water for spawning, 



368-370 

 and marine species in estuaries, 



368 

 and origination of life, 367-368 

 and routes by which animals left 



ocean, 367-368 

 and sea organisms in marshes, 



368 

 and spawning of eels, 370 

 and tolerance of marine organ- 

 isms to reduced salinity, 36b 

 most successful animal colonizers 



in, 367-368 

 through gradual change from salt 



water to fresh water, 368 

 through salt spray in supralittoral 



zone, 368 

 through wind action, 368 

 summary of factors in geographic 



distribution of organisms of, 



351 

 temperature of: 

 and movement of currents, 354 

 as constant in depths, 354 



Sea (Co>iliiiued) 



in depths, as varying more in 



tropics than elsewhere, 353-354 

 effect of on sea- shore animals, 



354 

 on surface, 353-354 

 thermoclines in, 353-354 

 tides of: 

 causes of, 352 

 ebb-tide, 352 

 effect of on animals in inter- tidal 



habitats, 352 

 flood- tide, 352 

 in bodies of water with narrow 



connection with sea, 352 

 nature of away from shore, 352 

 neap, 352 

 regularity of, 352 

 spring, 352 

 width of neritic biochore of, 351- 



352 

 zoogeographical system for divi- 

 sion of communities of, 370 

 Sere(s) (see also Subseres): 

 animal, on bare rock, 104-105 

 bioseres, grouping of into priseres 



and subseres, 22 

 changing of bogs into marshes as 

 result of cliseral succession, 

 92 

 classifications of, 21 

 clay: 

 birds in, 113 



climax forest in, 112-113 

 increase in invertebrate species 



with advance of, 112-113 

 mammals in, 113 

 most abundant animals in, 113 

 stages of plants in, 112 

 climax as last stage in biosere, 26 

 clisere in eastern North America, 



23-24 

 clisere in post- Pleistocene era, 



288-291 

 convergence as end of stages of, 



102 

 development of subsere following 



prisere, 22 

 eoseres in physiographic succes- 

 sion, 24 

 floodplain: 

 eastern U. S., variations in tree- 

 stage of, 113-114 

 example of, Mississippi in 



Western Tennessee as, 113 

 formation of through overflow of 

 streams, 113 

 geoseres, 24-26 



and speciation, 26 

 insects in, 1 14 

 plant stages in, 113 

 similarity of animal life of to that 

 of deciduous forest, 114 



(Sere(s) (Contiiiiied) 



toleration of animals of to flood- 

 ing in, 114-115, 115 

 length of time of various kinds of, 



26 

 maturity of soil profile in relation 



to, 170 

 microsere, stages of in dung on 



grassland, 125 

 occurrence of bioseres in micro- 

 habitats, 23 

 of coniferous forest, species 



composition of, 306 

 plant, in bogs, 92 

 plant, on bare rock, 102-104 

 pond, stages in and characteristic 



species, 79-81 

 pond, succession of animal adapta- 

 tions in, 81 

 rock, development of through salt 



spray on marine shores, 368 

 sand: 

 birds in, 110 

 changes in mores of spiders 



during, 109 

 changes in species of spiders in, 



109 

 characteristics of as habitat, 106- 



107 

 feeding- habits of grasshoppers 



in, 107 

 greatest change in species com- 

 position in, 107 

 insects in, 109-110 

 Lake Michigan, ideal nature of, 



105-106 

 Lake Michigan, stages in, 105 

 sand-binding plants in, 105 

 shifting species of ants in, 107-108 

 species of grasshoppers in, 107 

 two major ant communities in 



gradient of, 109 

 vertebrates in, 109-110, 110 

 Sessility: 

 as characteristic of some forms 



of benthos in sea, 359 

 as consideration in morphological 



adaptation, 7 

 as factor in competition for sur- 

 vival, 221 

 as factor in morphological adapta- 

 tion of trees, 7 

 of intertidal organisms and dis- 

 persal of motile larval into 

 proper zones, 362-363 

 of zooid and change in turgescence, 

 10 

 Seston, defined. 66 

 Sewall Wright effect, described. 262 

 Shelter (see also Habitats; Micro- 

 habitats; Niches): 

 animal response to life-forms of 

 plants in seeking, 248 



Index 44 



