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Phylum Annelida. Segmented worms a nnelus = little ring. Body Plan Cephalization One way digestive system Circulatory system Complex organs Segmentation (separated by septa). Annelids include 3 classes:. Leeches. Polychaetes (poly – ih – keets ) Poly = Many Chaeta = bristles.
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Phylum Annelida Segmented worms annelus = little ring
Body Plan • Cephalization • One way digestive system • Circulatory system • Complex organs • Segmentation (separated by septa)
Annelids include 3 classes: Leeches Polychaetes (poly – ih – keets) Poly = Many Chaeta = bristles Oligochaetes (awly – go – keets) Oligo = Few
Polychaetes • Marine worms – live in seas and oceans • Paired, paddle-like appendages • Poly – chaeta = many bristles
Oligochaetes • Include earthworms and related species • Live mainly in soil or fresh water • Fewer bristles than polychaetes (bristles help anchor them in burrows)
Leeches - Hirudinae • Includes leaches • Mostly freshwater, external parasites • Some are carnivorous • Powerful suckers on both ends of the body used for anchoring
Structural Complexity • True coelem • Complex organ systems