Thisisnotintendedtobeacomprehensivetextbookofentomology andarachnology,butratheraconcisesynthesisofcertainbasic informationrequiredfor BSc(Hons)andMSc(Entomology) examinations. Theapproachisprimarilyfunctional:forinstance, theskeletalandwaterproofingpropertiesofthearthropodcuticle arediscussed,butnotitsbiochemistry;andIhaveincludedonly thosepointswithwhichIbelievealladvancedstudentsofthesub* jectoughttobefamiliar. Someaspectsaretodayregardedas outdated;othersdonotappearinanycurrenttexts,butIhave includedthembecauseIconsiderthemtobeimportant. Innoway, therefore,shouldthisberegardedasabookofreference. Tobe frank,itconsistsofamassofoversimplificationsandunqualified generalizationswhichareintendedtoclarifythecomplexprinciples underlyingthem. OncetheseprincipleshavebeenthorougWy grasped,thereaderwillhaveacquiredasufficientlybroadapproach tobeabletogetthebestvaluefrommoreadvancedtreatises. MythanksareduetoDrs. JohnDalingwater,AndrewMilner, andespeciallyPaulHillyardfortheiradviceonpalaeontological matters;toProfessorsEinarBursellforpermissiontouseFig. 8, takenfromhis An Introduction to Insect Physiology(Academic Press),NeilF. HadleyandtheEditorsof American Scientistto reproduceFigs.52,53,andtoF. SchallerforFig. 42fromachap- terhewroteinGupta(ed. ) Arthropod Phylogeny(VanNostrand Reinhold). Finally,IwouldliketoexpressmygratitudetoRoy Abrahamsforredrawingthefiguresshowinginsectwingvenations andtoEileenBerghfortypingthemanuscript. Thebookwas completedduringtenureofaLeverhulmeEmeritusFellowship whichIampleasedtoacknowledge,whileProfessorN. A. Mitchison FRSkindlyprovidedmewithaccommodationinUniversityCol* lege,London. J. L. CWUDSLEY-THOMPSON Contents 1 PalaeontologyandPhylogeny...1 1. 1 TheEarliestArthropodanFossils...1 1. 2 TheFirstTerrestrialArthropods...2 1. 3 EvolutionintheArthropods...4 1. 3. 1 EmbryologicalConsiderations...4 1. 3. 2 ComparativeMorphology...5 1. 3. 3 MonophyleticorPolyphyleticOrigins...6 FurtherReading...9 2 ImplicationsofLiveonLand...10 2. 1 TheSignificanceofSize 10 2. 1. 1 Size,SkeletonsandAllometry 11 2. 1. 2 AllometricGrowth 12 2. 2 WaterRelations 12 2. 3 TheConquestoftheLand 14 2. 4 . TheIntegument 14 2. 4. 1 TheEndocuticle 15 2. 4. 2 TheExocuticle 15 2. 4. 3 TheEpicuticle 16 2. 5 GrowthandEcdysis 18 2. 6 Respiration:Lung-BooksandTracheae 19 2. 7 NutritionandExcretion 21 2. 7. 1 Nutrition 21 2. 7. 2 Excretion 22 2.8 EcologicalConsiderationsofSize 23 FurtherReading 25 3 TheConquestoftheLandbyCrustacea...26 3. 1 TypesofAdaptation...26 3. 2 TransitionfromWatertoLandinAmphipoda 26 3. 3 TransitionfromWatertoLandinDecapoda 28 3. 4 TransitionfromWatertoLandinIsopoda 30 3. 4. 1 Morphology 30 3. 4. 2Physiology...31 3. 4. 3 Behaviour 34 VIII Contents 3. 5 Conclusion 35 FurtherReading...36 4 InsectPhylogenyandtheOriginofFlight...37 4. 1 AncestryofInsects 37 4. 2 TheOriginofWings 38 4. 2. 1 Apte10taandtheAncestryofSpiders 39 4. 3 Paranota1Theory 40 4. 4 TrachealGillTheory . 42 4. 5 SelectionforFlight 43 4. 6 PhylogenyoftheLowerInsectOrders . 44 4. 6. 1 FossilEvidence .

Thisisnotintendedtobeacomprehensivetextbookofentomology andarachnology,butratheraconcisesynthesisofcertainbasic informationrequiredfor BSc(Hons)andMSc(Entomology) examinations. Theapproachisprimarilyfunctional:forinstance, theskeletalandwaterproofingpropertiesofthearthropodcuticle arediscussed,butnotitsbiochemistry;andIhaveincludedonly thosepointswithwhichIbelievealladvancedstudentsofthesub* jectoughttobefamiliar. Someaspectsaretodayregardedas outdated;othersdonotappearinanycurrenttexts,butIhave includedthembecauseIconsiderthemtobeimportant. Innoway, therefore,shouldthisberegardedasabookofreference. Tobe frank,itconsistsofamassofoversimplificationsandunqualified generalizationswhichareintendedtoclarifythecomplexprinciples underlyingthem. OncetheseprincipleshavebeenthorougWy grasped,thereaderwillhaveacquiredasufficientlybroadapproach tobeabletogetthebestvaluefrommoreadvancedtreatises. MythanksareduetoDrs. JohnDalingwater,AndrewMilner, andespeciallyPaulHillyardfortheiradviceonpalaeontological matters;toProfessorsEinarBursellforpermissiontouseFig. 8, takenfromhis An Introduction to Insect Physiology(Academic Press),NeilF. HadleyandtheEditorsof American Scientistto reproduceFigs.52,53,andtoF. SchallerforFig. 42fromachap- terhewroteinGupta(ed. ) Arthropod Phylogeny(VanNostrand Reinhold). Finally,IwouldliketoexpressmygratitudetoRoy Abrahamsforredrawingthefiguresshowinginsectwingvenations andtoEileenBerghfortypingthemanuscript. Thebookwas completedduringtenureofaLeverhulmeEmeritusFellowship whichIampleasedtoacknowledge,whileProfessorN. A. Mitchison FRSkindlyprovidedmewithaccommodationinUniversityCol* lege,London. J. L. CWUDSLEY-THOMPSON Contents 1 PalaeontologyandPhylogeny...1 1. 1 TheEarliestArthropodanFossils...1 1. 2 TheFirstTerrestrialArthropods...2 1. 3 EvolutionintheArthropods...4 1. 3. 1 EmbryologicalConsiderations...4 1. 3. 2 ComparativeMorphology...5 1. 3. 3 MonophyleticorPolyphyleticOrigins...6 FurtherReading...9 2 ImplicationsofLiveonLand...10 2. 1 TheSignificanceofSize 10 2. 1. 1 Size,SkeletonsandAllometry 11 2. 1. 2 AllometricGrowth 12 2. 2 WaterRelations 12 2. 3 TheConquestoftheLand 14 2. 4 . TheIntegument 14 2. 4. 1 TheEndocuticle 15 2. 4. 2 TheExocuticle 15 2. 4. 3 TheEpicuticle 16 2. 5 GrowthandEcdysis 18 2. 6 Respiration:Lung-BooksandTracheae 19 2. 7 NutritionandExcretion 21 2. 7. 1 Nutrition 21 2. 7. 2 Excretion 22 2.8 EcologicalConsiderationsofSize 23 FurtherReading 25 3 TheConquestoftheLandbyCrustacea...26 3. 1 TypesofAdaptation...26 3. 2 TransitionfromWatertoLandinAmphipoda 26 3. 3 TransitionfromWatertoLandinDecapoda 28 3. 4 TransitionfromWatertoLandinIsopoda 30 3. 4. 1 Morphology 30 3. 4. 2Physiology...31 3. 4. 3 Behaviour 34 VIII Contents 3. 5 Conclusion 35 FurtherReading...36 4 InsectPhylogenyandtheOriginofFlight...37 4. 1 AncestryofInsects 37 4. 2 TheOriginofWings 38 4. 2. 1 Apte10taandtheAncestryofSpiders 39 4. 3 Paranota1Theory 40 4. 4 TrachealGillTheory . 42 4. 5 SelectionforFlight 43 4. 6 PhylogenyoftheLowerInsectOrders . 44 4. 6. 1 FossilEvidence .

Thisisnotintendedtobeacomprehensivetextbookofentomology andarachnology,butratheraconcisesynthesisofcertainbasic informationrequiredfor BSc(Hons)andMSc(Entomology) examinations. Theapproachisprimarilyfunctional:forinstance, theskeletalandwaterproofingpropertiesofthearthropodcuticle arediscussed,butnotitsbiochemistry;andIhaveincludedonly thosepointswithwhichIbelievealladvancedstudentsofthesub* jectoughttobefamiliar. Someaspectsaretodayregardedas outdated;othersdonotappearinanycurrenttexts,butIhave includedthembecauseIconsiderthemtobeimportant. Innoway, therefore,shouldthisberegardedasabookofreference. Tobe frank,itconsistsofamassofoversimplificationsandunqualified generalizationswhichareintendedtoclarifythecomplexprinciples underlyingthem. OncetheseprincipleshavebeenthorougWy grasped,thereaderwillhaveacquiredasufficientlybroadapproach tobeabletogetthebestvaluefrommoreadvancedtreatises. MythanksareduetoDrs. JohnDalingwater,AndrewMilner, andespeciallyPaulHillyardfortheiradviceonpalaeontological matters;toProfessorsEinarBursellforpermissiontouseFig. 8, takenfromhis An Introduction to Insect Physiology(Academic Press),NeilF. HadleyandtheEditorsof American Scientistto reproduceFigs.52,53,andtoF. SchallerforFig. 42fromachap- terhewroteinGupta(ed. ) Arthropod Phylogeny(VanNostrand Reinhold). Finally,IwouldliketoexpressmygratitudetoRoy Abrahamsforredrawingthefiguresshowinginsectwingvenations andtoEileenBerghfortypingthemanuscript. Thebookwas completedduringtenureofaLeverhulmeEmeritusFellowship whichIampleasedtoacknowledge,whileProfessorN. A. Mitchison FRSkindlyprovidedmewithaccommodationinUniversityCol* lege,London. J. L. CWUDSLEY-THOMPSON Contents 1 PalaeontologyandPhylogeny...1 1. 1 TheEarliestArthropodanFossils...1 1. 2 TheFirstTerrestrialArthropods...2 1. 3 EvolutionintheArthropods...4 1. 3. 1 EmbryologicalConsiderations...4 1. 3. 2 ComparativeMorphology...5 1. 3. 3 MonophyleticorPolyphyleticOrigins...6 FurtherReading...9 2 ImplicationsofLiveonLand...10 2. 1 TheSignificanceofSize 10 2. 1. 1 Size,SkeletonsandAllometry 11 2. 1. 2 AllometricGrowth 12 2. 2 WaterRelations 12 2. 3 TheConquestoftheLand 14 2. 4 . TheIntegument 14 2. 4. 1 TheEndocuticle 15 2. 4. 2 TheExocuticle 15 2. 4. 3 TheEpicuticle 16 2. 5 GrowthandEcdysis 18 2. 6 Respiration:Lung-BooksandTracheae 19 2. 7 NutritionandExcretion 21 2. 7. 1 Nutrition 21 2. 7. 2 Excretion 22 2.8 EcologicalConsiderationsofSize 23 FurtherReading 25 3 TheConquestoftheLandbyCrustacea...26 3. 1 TypesofAdaptation...26 3. 2 TransitionfromWatertoLandinAmphipoda 26 3. 3 TransitionfromWatertoLandinDecapoda 28 3. 4 TransitionfromWatertoLandinIsopoda 30 3. 4. 1 Morphology 30 3. 4. 2Physiology...31 3. 4. 3 Behaviour 34 VIII Contents 3. 5 Conclusion 35 FurtherReading...36 4 InsectPhylogenyandtheOriginofFlight...37 4. 1 AncestryofInsects 37 4. 2 TheOriginofWings 38 4. 2. 1 Apte10taandtheAncestryofSpiders 39 4. 3 Paranota1Theory 40 4. 4 TrachealGillTheory . 42 4. 5 SelectionforFlight 43 4. 6 PhylogenyoftheLowerInsectOrders . 44 4. 6. 1 FossilEvidence .