Worm Phyla Phylum Platyhelminthes Phylum Nematoda Phylum Annelida

Phylum Annelida 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 (coelem) surrounded by muscles Cephalopods (have a head) Concentrated with nerve cells and sensory structures Worm Video

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!) Flatworm video http://www.ucmp.berkeley.edu/platyhelminthes/pseudobiceros.jpg

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).

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.