1. Phylum Nematoda Phylum Platyhelminthes Phylum Annelida

2.  The name means “little rings”  earthworms and leeches  segmented bodies (internal and external)  Bilateral symmetry  Systems – nervous, digestive (gut, mouth, anus), closed circulatory  Sexual Reproduction  Hydrostatic skeleton  fluid-filled cavity (coelom) surrounded by muscles  Cephalopods (have a head)  Concentrated with nerve cells and sensory structures

3. Phylum Platyhelminthes  Flatworms  un-segmented (no rings) and appear flat  most no more than a few millimeters thick.  have tissues and internal organs systems  bilateral symmetry,  cephalization (which means they have a head!) http://www.ucmp.berkeley.edu/platyhelminthes/pseudobiceros.jpg

4. Flatworm Characteristics  single digestive opening (Mouth/Anus)-food enters and undigested waste leaves.  Because they are so thin, most flatworms do not need a circulatory system to transport materials, but use diffusion.  Respiration also occurs through diffusion  They move to obtain food and escape predators.  They can be both carnivorous or parasitic (this tapeworm lives inside the human intestines).

5. Phylum Nematoda  Roundworms  unsegmented worms  microscopic or a large as a meter in length!  Most roundworms are free living and are found in the soil, the sea floor, or water.  Others are parasites that live in plants and animals.