Bilaterate PhylaBilaterate Phyla

Phylogeny ReviewPhylogeny Review

ancestorCommon metazoan

Simple Bilaterian PhylaSimple Bilaterian Phyla

Phylum PlatyhelminthesPhylum Platyhelminthes

TriploblasticTriploblastic Bilaterally SymmetricBilaterally Symmetric AceolomicAceolomic

Body Cavity ClassificationBody Cavity Classification

Acoelomate Internal Acoelomate Internal OrganizationOrganization

Platyhelminthe Taxonomic Platyhelminthe Taxonomic CharacteriesticsCharacteriestics Free-living v parasiticFree-living v parasitic

Incomplete gutIncomplete gut No circulatory systemNo circulatory system Centralized nervous systemCentralized nervous system Secretory glandsSecretory glands Excretory organsExcretory organs Reproductive Reproductive

organs organs InnervatedInnervated

musculature musculaturePseudoceros bifurcus

Platyhelminthes Reproduction Platyhelminthes Reproduction ModesModes SexualSexual

Monoecious (hermaphroditic)Monoecious (hermaphroditic) Free living forms typically cross fertilizeFree living forms typically cross fertilize Schistosoma spSchistosoma sp of flukes are dioecious of flukes are dioecious

AsexualAsexual Freshwater turbellarians’ regenerative propertiesFreshwater turbellarians’ regenerative properties Intermediate forms of parasitic classesIntermediate forms of parasitic classes

Sporogomy of encysted miracidium and redia Sporogomy of encysted miracidium and redia formsforms

Platyhelminthes TaxonomyPlatyhelminthes Taxonomy

Class TurbellariaClass Turbellaria Free living planarians & marine flatwormsFree living planarians & marine flatworms

Class TrematodaClass Trematoda Internal FlukesInternal Flukes

Class MonogeneaClass Monogenea External FlukesExternal Flukes

Class CestodaClass Cestoda TapewormsTapeworms

All Parasitic

Class Turbellaria – PlanarianClass Turbellaria – Planarian

Dugesia sp

Movement of Free Living Movement of Free Living TurbellariansTurbellarians crawling crawling DugesiaDugesia

crawling crawling BdelluraBdellura

swimming swimming polycladpolyclad

Generalized Turbellarian Generalized Turbellarian AnatomyAnatomy

Turbellarian Organ Systems Turbellarian Organ Systems

Protonephridia –Flame cells & tube cells

Turbellarian Organ SystemsTurbellarian Organ Systems

Orders of Class TurbellariaOrders of Class Turbellaria

OrderTricladida

OrderPolycladida

Phylum PlatyhelminthesPhylum Platyhelminthes Class Turbellaria Class Turbellaria

Two tiger flatworms Two tiger flatworms ((Pseudoceros Pseudoceros crozerricrozerri) on clump ) on clump of orange sea squirts of orange sea squirts ((Ecteinascidia Ecteinascidia turbinata: turbinata: tunicates) tunicates) in Bermudain Bermuda

Photo Copyright © Diane R. Nelson

Phlym PlatyhelminthesPhlym PlatyhelminthesClass Turbellaria, Class Turbellaria,

Order PolycladidaOrder Polycladida

Pseudocerus Pseudocerus hancockanumhancockanum

CoralCoral – Tubastrea – Tubastrea aurea aurea

TunicateTunicate – Aplidium – Aplidium cratiferum cratiferum

Phlym PlatyhelminthesPhlym PlatyhelminthesClass Turbellaria, Class Turbellaria,

Order PolycladidaOrder Polycladida

Amphiscolops spAmphiscolops sp

The flatwormThe flatworm Mesostoma, Mesostoma, catching and eatingcatching and eating Daphnia Daphnia

Video Clip

Class Trematoda - FlukesClass Trematoda - Flukes

Require 2 or more hostsRequire 2 or more hosts Definitive hostDefinitive host

Where sexually reproducing fluke livesWhere sexually reproducing fluke lives Intermediate hostsIntermediate hosts

Intermediate larval/asexual forms encystIntermediate larval/asexual forms encyst

Generalize Fluke Body PlanGeneralize Fluke Body Plan

Parasitic Life CyclesParasitic Life Cycles HostsHosts

Single v multipleSingle v multiple Multiple hostsMultiple hosts

DefinitiveDefinitive Sexually reproductive stage of parasiteSexually reproductive stage of parasite

IntermediateIntermediate Asexually reproducing stages, larval stages of Asexually reproducing stages, larval stages of

parasiteparasite Parasitic adaptationsParasitic adaptations

Syncytial tegumentSyncytial tegument Loss of centralized nervous systemLoss of centralized nervous system Decreased digestive & excretory systemsDecreased digestive & excretory systems

Fluke HostsFluke Hosts

Definitive HostsDefinitive Hosts Mammals, Reptiles, BirdsMammals, Reptiles, Birds

Intermediate HostsIntermediate Hosts ArthorpodsArthorpods GastropodsGastropods FishFish

Clonorchis sinensis Life Cycle – Human Liver Fluke

Trematode StagesTrematode Stages

Adult – fluke in liver, bile ducts, respiratory tract, Adult – fluke in liver, bile ducts, respiratory tract, bloodblood

Miracidium – ciliated, swimming larvaeMiracidium – ciliated, swimming larvae Sporocyst – asexually reproductive stage producing Sporocyst – asexually reproductive stage producing

redia (within sporocyst)redia (within sporocyst) Redia – 2Redia – 2ndnd asexual phase producing cercaria asexual phase producing cercaria Cercaria – free swimming larval form Cercaria – free swimming larval form Metacercaria – encysted cercariaMetacercaria – encysted cercaria

ClonorchisClonorchis Stages Stages

Adult Fluke

Egg

Sporocyst

RediaCercaria

Metacercarial cyst

Blood Flukes:Blood Flukes:Schistosoma Schistosoma japonicumjaponicum & & Schistosoma Schistosoma mansonimansoni

Swimmer’s ItchSwimmer’s Itch

Encysted metacercaria of Encysted metacercaria of avian schistosomesavian schistosomes

Class MonogeneaClass Monogenea

Monogenea – 1 hostMonogenea – 1 host External flukesExternal flukes

Fish gillFish gill No intermediate hostsNo intermediate hosts

Class Cestoda - TapewormsClass Cestoda - Tapeworms Two hostsTwo hosts

Definitive host – carnivoreDefinitive host – carnivore Intermediate host – herbivore Intermediate host – herbivore

Adults live in intestine of Adults live in intestine of definitive hostdefinitive host

Larval stages encyst in muscleLarval stages encyst in muscleof intermediate hostof intermediate host

Cestode Body PlanCestode Body Plan

Attach via scolexAttach via scolex Proglottids develop from Proglottids develop from

base of scolexbase of scolex Proglottids mature Proglottids mature

reproductivelyreproductively Proglottids are shed in Proglottids are shed in

feces or crawl from anal feces or crawl from anal openingopening

Taenia Taenia saginata saginata Life CycleLife Cycle- Human/Beef - Human/Beef TapewormTapeworm

Taenia solium – Human/Pork Taenia solium – Human/Pork TapewormTapeworm

Broad fish Tapeworm Broad fish Tapeworm Diphyllobothrium latumDiphyllobothrium latum

Cestode Cestode OrgansOrgans Each proglottid Each proglottid

matures as an egg matures as an egg sacksack

Host SpecificityHost Specificity

Hydatid CystsHydatid Cysts Encystment of larva in definitive rather than Encystment of larva in definitive rather than

intermediate hostintermediate host CysticercosisCysticercosis Taenia soliumTaenia solium and and T. saginataT. saginata

Hydatid Cysts in Human HeartHydatid Cysts in Human Heart

Hydatid Cysts in Human BrainHydatid Cysts in Human Brain