Diversity of Life – Animals (flatworms, tapeworms) PLATYHELMINTHES (flatworms, tapeworms)

A Phylogeny of the Animal Phyla Porifera No true tissues Cnidaria radial symmetry diploblastic Ctenophora Platyhelminthes Acoelomates Rotifera Pseudocoelomates Nematoda Nemertea Mollusca Protostomes true tissues Annellida Arthropoda Bilateral symmetry triploblastic Bryozoa Lophophorate phyla Body cavity Phoronida Coelomates Brachiopoda Echinodermata Chordata Deuterostomes

Platyhelminthes - flatworms Description Animals that are • triploblastic • no body cavity(aceolomate) • central nervous system • bilateral symmetry

Platyhelminthes - flatworms Free living flatworms Tapeworms Flukes

Tissue Layers There can be two or three Ectoderm Mesoderm Endoderm Diploblastic Triploblastic

3. Body Cavities - There are three different kinds Coelomate - the coelom is lined on both sides with mesoderm Pseudocoelomate - the coelom (= pseudocoelom) is lined on one side with mesoderm Acoelomate - there is no body cavity between the digestive tract and body wall

Platyhelminthes - flatworms Basic Structure - body plan Acoelomate!! mesoderm endoderm ectoderm

Platyhelminthes - flatworms Basic Structure - a few improvements Excretion

Platyhelminthes - flatworms Basic Structure - a few improvements Digestion -digestion begins in the pharynx and nutrients are absorbed in the gastrovascular cavity

Platyhelminthes - flatworms Basic Structure - a few improvements Nervous system Eyespots

Platyhelminthes - flatworms Basic Structure - a few improvements Nervous system Cephalization

Platyhelminthes - Classification Turbellaria - free living flatworms -mostly marine, predators and scavengers

Platyhelminthes - Classification 2. Trematoda - flukes - vertebrate parasites

Platyhelminthes - Classification 2. Trematoda - flukes

Platyhelminthes - Classification 3. Cestoda (= Cestoidea) - tapeworms - vertebrate parasites

Platyhelminthes - Classification 3. Cestoda (= Cestoidea) - tapeworms - vertebrate parasites Sucker discs Hooks- for attachment to host’s intestine Scolex

Platyhelminthes - Classification 3. Cestoda (= Cestoidea) - tapeworms - vertebrate parasites proglottid

Platyhelminthes - Classification 3. Cestoda - tapeworms- Beef tapeworm- Life cycle Mature adult in human intestine Larvae release in sewage Juveniles encyst in cow muscle

Platyhelminthes - Classification 3. Cestoidea - tapeworms- Beef tapeworm- Life cycle

Platyhelminthes - Classification 3. Cestoda - tapeworms- Beef tapeworm- Life cycle Mature adult in human intestine Larvae release in sewage Juveniles encyst in cow muscle

Symmetry Body Cavity Skeletal Digestive Excretory Nervous Reproductive Porifera None Spicules in mesohyl Phagocytosis Amoebocytes Hermaphrodites Asexual Cnidaria Radial None – stiffened mesoglea Nutritive muscle cells Nerve net Specialized zooids or asexual Platyhelminthes Bilateral (acoelo-mate) Incomplete Flame cells Cephalized CNS Hermaophrodite