4/29/13 Objective: Phylum Nematoda and Phylum Annelida *Take out HW (23.4 and 23.5) Do Now: a.What kind of symmetry to platyhelminthes have? b.What type of body cavity?

Phylum Nematoda (Roundworms) Have bilateral symmetry and 3 tissue layers like flatworms Different from flatworms because they have: Complete Digestive Tract: - Opposite mouth and anus - Digestive tube

Body Plan Pseudocoelm “false cavity”: - fluid filled body cavity in direct contact with the digestive tract

Diversity Most are free-living and decomposers Some are Parasites Ex: Heartworm

Phylum Annelida (Annelids) aka Segmented Worms Body Plan -Divided into sections by internal walls- -Digestive tract, nerve cord, and main blood vessels not segmented Have bilateral symmetry and 3 tissue layers

Closed Circulatory System: Blood remains in vessels - nutrients, oxygen, and wastes diffuse

Coelom True, fluid filled body cavity in contact with internal tissues

Anatomy Pharynx: beginning of digestive tract Crop: stores food temporarily Gizzard: soil mixture is ground up Clitellum: area near anterior end creates cocoons for offspring Setae: tiny hairs on ventral side for movement

Class Polychaeta Ex: Marine clam worm or “sand worm”

Class Oligochaeta Example: Earthworms Description: Churns and aerates the soil

Class Hirudinea Example: Leeches Description: Parasitic