Diversity of Life – Animals

PLATYHELMINTHES (flatworms, tapeworms)

Porifera

Cnidaria Ctenophora Platyhelminthes Rotifera

Nematoda Nemertea Mollusca Annellida Arthropoda Bryozoa

Phoronida Brachiopoda Echinodermata Chordata

No true tissues

radial symmetry diploblastic

true tissues

Acoelomates

Deuterostomes

Bilateral symmetry triploblastic

Body cavity

Protostomes

Lophophorate phyla

Pseudocoelomates

Coelomates

A Phylogeny of the Animal Phyla

Platyhelminthes - flatworms

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

Platyhelminthes - flatworms

Free living flatworms Tapeworms

Flukes

There can be two

Ectoderm

Endoderm

or three

Mesoderm

Diploblastic Triploblastic

Tissue Layers

Body Cavities

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

3. Body Cavities - There are three different kinds

Platyhelminthes - flatworms

Basic Structure - body plan

endoderm mesoderm ectoderm

Acoelomate!!

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

1.  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

Hooks- for attachment to host’s intestine

Sucker discs

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 None Spicules in mesohyl

Phagocytosis Amoebocytes None Hermaphrodites Asexual

Cnidaria Radial None None – stiffened mesoglea

Nutritive muscle cells

Non e Nerve net Specialized zooids or asexual

Platyhelminthes Bilateral None (acoelo-mate)

None Incomplete Flame cells Cephalized CNS

Hermaophrodite Asexual