Platyhelminthes Flatworms Tapeworms Flukes

PHYLUM PLATYHELMINTHES Bilateral Triploblastic Acoelomate –Gastrovascular cavity Cephalization Ladder-like nervous system Protonephridia with flame cells

Fig

Symmetry

Traditional View Continues Acoelomate - Pseudocoelomate vs Coelomate Aceolomate no space between tissue layers, no cavity

Protonephridia with Flame cells

Class Turbellaria Free living flatworms Example: Dugesia (Planaria)

External Anatomy

Ladder-like nervous system No real “brain”, but anterior ganglia

Ladder Nervous System

Fig

Planaria c.s.

Class Trematoda Flukes All parasitic Possess two suckers Have complex life cycles Need multiple hosts

Chlornorchis sinensis

Fasciola hepatica w.m.

Schistosoma sp. w.m.

Schistosomiasis

eosinophylls attacking a larval fluke.

Class Cestoda Tapeworms Scolex and proglottids Segmented

Diplydium caninum

Scolex Anatomy Rostellum Suckers Neck

Tapeworm development

Proglottid anatomy Uterus Genital pore Ovary Testis

Echinococcus granulosus w.m.

Hydatid cyst Capsules of scolices

Hydatid Cyst Disease