The Segmented Worms

PHYLUM ANNELIDA

INTERNAL ANATOMY

INTERNAL ANATOMY

https://www.youtube.com/watch?v=u9HHS1uPFSo

• 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

HIRUDINEA – THE LEECHES

• This leech has an anterior sucker for feeding and a posterior sucker for attachment

• https://www.youtube.com/watch?v=ye4N2ZeJESA

HIRUDINEA – THE LEECHES

• 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

• https://www.youtube.com/watch?v=kIoN2PCvL4o

• https://www.youtube.com/watch?v=UuApLH8rlwY

CLASS POLYCHAETAE

• Note the clitellum – a reproductive structure that will form a protective case for the eggs & larvae

• Note the specialization of anterior and posterior segments

• https://www.youtube.com/watch?v=uO4lkv-jLRs

CLASS OLIGOCHAETAE – THE EARTHWORMS

• Earthworms are monoecious (hermaphroditic), but cannot self-fertilize

• https://www.youtube.com/watch?v=bFpblBf1dfE

EARTHWORM REPRODUCTION