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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
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