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Labs
Porifera
Cnidaria
Platyhelminthes
Nematoda
Mollusca
Annelida
Onychophora
Arthropoda
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Phylum Platyhelminthes
Common Name: Flatworms, tapeworms, and flukes.
Etymology: "Flat worms", from the Greek platy for flat
and helminthes for
worms.
Representative examples:
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| The terrestrial triclad Bipalium |
A free-living, terrestrial, tropical flatworm. |
Planaria.
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Unidentified, interridal polyclad flatworm from the
Sea of Cortez, Mexico |
The strikingly colored polyclad Pseudoceros ferrugineus |
Symmetry: Bilateral
Tissue Layers: 3
Coelom: Acoelomate
Digestive Tract: Incomplete (usually), but may be highly branched to
increase surface area.
Additional Information:
The flatworms are a group of acoelomate (lacking
a body cavity) animals characterized by their ribbon-like, dorsoventrally
flattened bodies and simple general structure. They lack respiratory
and circulatory systems and have only very simple central nervous systems
consisting of longitudinal nerve cords with small anterior ganglia
and simple sensory structures. Although many are free-living predators,
several
groups of platyhelminths are dominated by parasitic species such as
tapeworms and flukes. |
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Links:
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| The familiar freshwater triclad Dugesia |
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Prosthecereus vittatus. An aquatic turbellarian
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