1. Phylum annelida
The Segmented Worms

2. Internal anatomy

3. Internal anatomy

4. Hirudinea – the leeches
Note the adaptation of the mouth to the parasitic niche of the leeches
Note also the segmentation which makes it similar to the other annelid worms

5. Hirudinea – The leeches
This leech has an anterior sucker for feeding and a posterior sucker for attachment
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6. Class Polychaetae Note the parapodia
Parapodia are expanded groups of structures (including lobes and setae) used for locomotion and gas exchange
Note also the specialization of segments and well developed cephalization
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7. Class oligochaetae – the earthworms
Note the clitellum – a reproductive structure that will form a protective case for the eggs & larvae
Note the specialization of anterior and posterior segments
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8. Earthworm reproduction
Earthworms are monoecious (hermaphroditic), but cannot self-fertilize