The document discusses four phyla of worms: Platyhelminthes, Nemertea, Nematoda, and Annelida. Phylum Platyhelminthes includes flatworms which have bilateral symmetry and specialized tissues. They have a simple nervous system and digestive system. Some are parasites. Phylum Nemertea contains ribbon worms, which have a complete digestive tract and circulatory system. They are predators that use a proboscis to capture prey. Phylum Nematoda are roundworms or nematodes with hydrostatic skeletons. Some are parasites in tissues. Phylum Annelida includes segmented worms like earthworms. They have a segmented body

1. WORMS!!!!! Phylum Platyhelminthes Phylum Nemertea Phylum Nematoda Phylum Annelida

2. Bilateral Symmetry Arrangement of body parts in such a way that there is only one way to cut the body and get two identical halves

3. Orientation Anterior – front Posterior – rear or back Dorsal – back Ventral - belly

4. Bilateral Charact. Bilateral symmetry allows for the following: A head with a brain More active pursuit of prey Body has specialized tissues and organs More sophisticated behaviors

5. Phylum Platyhelminthes “ Flatworms” Dosrsoventrally flattened (flat backs and bellies) Simplest organisms whose tissues are organized into real organs and organ systems

6. Phylum Platyhelminthes Has a central nervous system with a simple brain and nerve cords along the body There is a well developed muscular system, reproductive, and digestive system

9. Phylum Platyhelminthes a) Can be carnivorous b) Can live inside or on the surface of organisms c) Parasites such as flukes and tapeworms

10. Phylum Nemertea “ Ribbon worms” Look like long flat worms One measured at 30m long

11. Phylum Nemertea Defining characteristics: Complete digestive tract: mouth, gut, anus Presence of a circulatory system Most distinctive feature is a probiscus All predators that feed on worms and crustaceans

12. Proboscus A long, fleshy tube used to entangle prey Everted from a cavity above the mouth like a finger in a glove

13. Phylum Nematoda “ Roundworms” or Nematodes Live in sediments or the tissues of other organisms (parasites) Slender, cylindrical bodies are typically pointed at both ends

14. Phylum Nematoda Hydrostatic skeleton that provides support and locomotion Larva can be found in raw fish which is in turn ingested by humans

16. Phylum Annelida “ Segmented Worms” Body consists of a series of segments (think earthworm) Gut goes through all segments Contain a central cavity known as a coelom

17. Phylum Annelida Closed circulatory system – blood always stays in blood vessels Typically burrowers Includes Leeches