CONTENTS 



13 ECTOPROCTA THROUGH ECHIUROIDEA 213 

 Unsegmented Schizocoels 



Lophophorata -13 



Ectoprocta 213 



Phoronida 215 



Brachiopoda 215 

 Unsegmented Schizocoela 216 



Sipunculoidea 216 



Mollusca 217 



Echiuroidea 223 



14 ANNELIDA AND ARTHROPODA 224 

 Segmented Schizocoels 



Segmented, Worm-like Schizocoela: Annelida 224 

 Segmented, Joint-Legged Schizocoela : Arthropoda 229 



Subphylum Onychophora 230 



Subphylum Trilobita 230 



Subphylum Chelicerata 230 



Subphylum Pentastomida 235 



Subphylum Tardigrada 235 



Subphylum Mandibulata 236 



15 CHAETOGNATHA THROUGH LOWER 

 CHORDATA 254 

 Invertebrate Eucoelomates 



Radial Enterocoela: Echinodermata 254 



Subphylum Pelmatozoa 256 



Subphylum Eleutherozoa 256 

 Questionable Enterocoela: Chaetognatha 260 

 Bilateral, Nonchordate Enterocoela 261 



Hemichordata 261 



Pogonophora 262 

 Chordate Enterocoela: Chordata 263 



Subphylum Tunicata 263 



Subphylum Cephalochordata 265 



16 SUBPHYLUM VERTEBRATA 266 

 Higher Chordates 



Vertebrate Affinities: Subphylum Vertebrata 266 



Fishes: Superclass Pisces 268 



Land Vertebrates; Superclass Tetrapoda 279 



17 ECOLOGICAL FACTORS 298 

 The Environment 



Limiting Factors 298 



Tolerance 298 



Ecological Amplitude 299 

 Ecological Factors 300 



Microhabitat 301 

 General Climate 302 



Climatic Rhythms 302 



Plant Life Forms 302 



Cliseral Movements 304 

 Temperature 304 



Temperature Variations 304 



Temperature Inversion 305 



Organism Reactions 305 

 Water 307 



Water Needs and Transpiration 307 



Available Moisture 307 



Plant Dormancy 308 



Plant-Water Relations 309 



Animal-Water Relations 310 



Intertidal Environment 31 1 



Fresh- Water Environment 315 

 Light 322 



Wavelength, Intensity, and Duration 322 



Photoperiodism 323 

 Atmosphere 323 



Wind 324 

 Soil 327 



Soil Texture 327 



Organic Matter 327 



Soil Moisture 328 



Soil Reaction 328 



Salinity 328 



Soil Animals 329 

 Fire 330 



Fire Adaptations 330 



Chaparral 331 



Controlled Burning 331 

 Topography 331 



Vegetation Zonation 332 

 Biotic Factors 333 



Symbiosis 333 



Interorganism Relationships 334 

 Ecological Variations 335 



Diurnation 336 



Aspectation 336 

 Ecological Success 336 



18 POPULATION ECOLOGY 

 Relations within a Species 



Population Origin 339 

 Population Extinction 340 

 Population Fluctuations 340 



Reproductive Rate 340 



Mortality Rate 341 

 Population Variations 341 



Causes of Population Cycles 341 



Carrying Capacity 342 



339 



