1. Flatworms – Phylum Platyhelminthes

2. Flatworms

3. Phylum Platyhelminthes Characteristics: -Marine, freshwater, and terrestrial -Flat, solid-bodied worms -Bilateral symmetry -Gastrovascular cavity -One body opening

4. Flatworm Organ Systems Digestive System Gastrovascular Cavity Pharynx Excretory System Excretory Canal Excretory Pore Nervous System Nerve Cord Brain

5. Class Turbellaria -planarians -free-living

7. Class Trematoda -flukes -parasites

8. Roundworms Phylum Nematoda Characteristics: -Aquatic and terrestrial, very numerous -Slender, thread-like worms -Bilateral symmetry -Complete digestive tract -Two body openings

9. Bryozoans Phylum Ectoprocta

10. Phylum Annelida Segmented Worms Characteristics: -Aquatic, terrestrial, or parasitic -Bilateral symmetry -Segmented body -Well developed organ systems -Closed circulatory system

11. Annelids  Class Polychaeta - mostly marine worms, such as Nereis (the clamworm) Nereis  Class Hirudinea - the leeches (predominantly freshwater), such as Hirudo leeches  Class Oligochaeta - mostly freshwater and terrestrial worms, such as Lumbricus (the earthworms)

12. Class Polychaeta - marine worms

13. Proboscis Worms Phylum Rhynchocoela Characteristics: -Marine -Ribbon-like worms -Protrusive throat with piercing jaws

14. Rotifers Phylum Rotifera Characteristics: -Aquatic, free living, microscopic -“Wheel animals” -Bilateral symmetry -Well developed organ systems

15. Rotifers Phylum Rotifera

16. Proboscis Worms Phylum Rhynchocoela