lecture_notes_12_10_07 - Lecture Notes 12-10-07 Flatworms,...

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Lecture Notes 12-10-07 Flatworms, Mollusks, Annelids Clade Bilateria : Animals with bilateral symmetry, most with triplobalstic development (ectoderm, endoderm, mesoderm) and a true coelom Leads to “Organ Grade of Organization” Three main groups: Lophotrochozoa; Ecdysozoa; Deuterostomes Lophotrochozoans: Flatworms; Mollusks; Annelid Worms The name of this clade comes from a type of feeding structure, the lophophore, shared by some group members, and a type of larva the trochophore, found in others (for example, mollusks and annelid worms) . The lophophore is a row of tentacles with cilia that surround the mouth of the organism. The cilia draw water towards the mouth and the tentacles trap suspended food particles Brachiopods have lophophores (See also Figure 33.14) Trochophore larvae (Mollusks and Annelid Worms) (Figure 32.13) Bands of cilia around the middle Used for swimming and to gather food Eat plankton The Flatworms (May be part of Lophotrochozoans), or may be separate group Have no true body cavity (coelom) (current theory is that this group descended from an ancestor which did have a coelom) and have a gastrovascular system with only one opening. Often the digestive sac is highly branched to increase the surface area available for the absorption of nutrients (Fig. 33.10)
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This note was uploaded on 04/29/2008 for the course BIOCORE 301 taught by Professor Howell during the Fall '07 term at Wisconsin.

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lecture_notes_12_10_07 - Lecture Notes 12-10-07 Flatworms,...

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