Pseudocoelomates - Pseudocoelomates Coelomates: Molluska...

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Unformatted text preview: Pseudocoelomates Coelomates: Molluska and Annelida The Pseudocoelomates • Internal body cavity – pseudocoel serves as hydrostatic skeleton • gains rigidity from being filled with fluid under pressure • More efficient muscle movement – lack a defined circulatory system • Fluids movement within the pseudocoelo. • The fluid movement changes the shape of the animal • The fluid presses the muscles producing a forward movement. The Pseudocoelomates • Phylum Nematoda : roundworms • Most primitive digestive tract (separate mouth and anus. – bilaterally symmetrical unsegmented worms • covered by flexible, thick cuticle – mouth equipped with stylets (piercing organs) – food passes through mouth as result of sucking action of pharynx (muscular chamber) – lack flagella or cilia – reproduction is sexual – Trichinella regularly parasitize humans Roundworms Nematode Mouth Pharynx Intestine Anus Nematode-Caused Diseases • Trichinosis - Trichinella • P i n w o r m s- Enterobius • Intestinal roundworms - Ascaris • Filariasis - Filaria The Pseudocoelomates • Phylum Rotifera : rotifers – small, bilaterally symmetrical, basically aquatic animals with a crown of thick cilia at their heads – well developed food processing apparatus – “wheel animals” • Phylum Cycliophora – relatively new • circular mouth surrounded by fine, hairlike cilia Rotifers Cycliophorans Coelomates: Mollusks • Mollusks (Mollusca) – extremely diverse – characterized by a coelom • great economic significance – pearls – mother of pearl • economic / environmental costs – zebra mussel invasion – intermediate hosts for parasites Body Plan of the Mollusks...
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This note was uploaded on 08/03/2010 for the course BIO 1500 taught by Professor Pandolfi during the Fall '08 term at Wayne State University.

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Pseudocoelomates - Pseudocoelomates Coelomates: Molluska...

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