Nematoda: Roundworms First phylum to have the Complete digestive tract: mouth and anus Pseudocoelomate: fluid filled between endoderm and mesoderm Hydrostatic skeleton under pressure which means only one shape is possible (tapered hotdog)

Phylum Nematoda Reproduction is usually sexual—females are generally larger than males. Fertilization is internal, and a female can deposit 100,000 or more fertilized eggs per day. The zygotes of most species are resistant cells capable of living in harsh conditions. Hookworm

Roundworms Pinworm Ascaris: intestinal roundworm 1,000,000 cases in USA: 1.2 billion worldwide Heartworm

Ascaris life cycle

Removal of Guinea Worm http://www.youtube.com/watch?v=mUz9gqLmyQ0

nematodes http://www.youtube.com/watch?v=JBLemM3tzRM soil nematodes http://www.youtube.com/watch?v=gmFHnQKbSM8 lymphatic filariasis (elephantiasis) 1 billion worldwide

Annelida: segmented worms Polychaetes, earthworms, leeches Eucoelomate Segmented body plan Closed circulatory system Protostome: opening in gastrula becomes the mouth

Annelida: key structures Bristles on side Aortic arches

leeches Fused segments to allow for blood storage Blood thinner released to help sucking

http://www. youtube. com/watch http://www.youtube.com/watch?v=DZig6EL5B6A&feature=PlayList&p=F648EFCC1BE6AAA3&playnext=1&index=10 Earthworms in Australia Earthworms are hermaphroditic. They fertilize each other with the clitellum secreting a mucus sack to collect the eggs and sperm. This sack is then placed into the ground until babies are developed.

annelids Polychaete: clamworm http://www.youtube.com/watch?v=LdHzRNdz2HU