1. Flatworms, Roundworms, & Segmented Worms

2. Phylum Platyhelminthes
Flatworms
Flat and thin bodies
Bilateral symmetry
Most are parasitic

3. Phylum Platyhelminthes
Flatworms include planarians, flukes, and tapeworms
20,000 species of flatworms

4. Miscellaneous Information- Flatworms
Movement- use of moving bodies of water or damp soil, or larger animals transporting them
Nutrition- parasitic; the flatworm will take in food through same opening it eliminates waste
Circulatory system- Gastrovascular cavity with one opening
Digestion and excretion occur through same opening
Reproduction- flatworm splits in two forming a new flatworm

5. Tapeworms Information
Can get tapeworm infection by ingestion of food or water contaminated with tapeworm eggs or larvae
Can cause intestinal infections
Symptoms- poor appetite, diarrhea, weakness, gastrointestinal discomfort

6. Phylum Nematoda Roundworms Ex. Pinworms and hookworms
90,000 species of nematodes
Bilateral Symmetry
Live in wet soil or water
Eat dead leaves and other materials
Some eat insects that destroy plant roots
Some destroy plant roots

7. Flatworm Head Head holds attachment hooks for host attachment
2 eyespots to help detect light
Also contains brain called 2 simple brains called ganglia- simple bundles of nerves

8. Phylum Nematoda Some roundworms can live in humans and make them sick
Roundworms have a complete digestive tract with 2 openings

9. Nervous System of Roundworms
Two nerve cords that transmit impulses in the roundworm

10. Miscellaneous Information- Roundworms
Reproduction- sexually, eggs deposited in soil after fertilization
Bilateral symmetry
No formal respiration, circulation, skeletal systems

11. Phylum Nematoda

12. Phylum Annelida Annelids are segmented worms
Bodies are divided into many sections or segments
Live in moist soil, freshwater, or saltwater
15,000+ species of annelids
Examples: earthworms and leeches

13. Phylum Annelida Earthworms
Have bristlelike Setae on each segment- helps in movement
Tunnel through soil to eat small pieces of food
Tunnels will loosen the soil and allow air to enter which helps plants to grow

14. Leeches and Us Used in medicinal treatment
Abscesses, painful joints, glaucoma, myasthenia, and to heal venous diseases and thrombosis

15. Phylum Annelida

16. Miscellaneous Information- Segmented Worms
Nervous system- ganglia nerve centers in each segment that are connected by nerve cords to brain
Closed circulatory system- like humans
Gas exchange through skin- need for worm to live near water
Digestion- complete internal digestive tract that runs length of body
Gizzard- muscular sac and hard particles help grind soil and food before they pass into intestine
Nephridia- collect/remove waste from each segment
Pg. 731 is a good reference for earthworm body

17. Miscellaneous Information- Segmented Worms
Reproduction- Hermaphrodites
Produce both eggs and sperm

18. Phylum Annelida Leeches Eat small invertebrates
Can attach to skin of vertebrates and feed on its blood
Anesthetics in chemicals of bite to prevent pain
Leech secretes chemical so blood does not clot

19. Bilateral Symmetry and Body Plans
All bilaterally symmetrical animals developed from 3 embryonic cell layers:
Ectoderm
Endoderm
Mesoderm
3 types- Acoelomates, Pseudocoelomates, Coelomates

20. Acoelomates Develop from the 3 layers but have no body cavities
Digestive tract extends throughout body
May have been first group of animals to evolve
Ex. Flatworms

21. Acoelomates

22. Pseudocoelomates Develop from the 3 layers
BUT also has a space that develops between the endoderm and mesoderm- called a pseudocoelom (difference between flatworm and roundworm)

23. Pseudocoelomates

24. Coelomates
Body cavities form from Coelom (fluid filled space that is completely surrounded by mesoderm where specialized organs and organ systems, serves to cushion and protect organs)
Humans, insects, fishes
Example: Earthworm
Greatest diversity among animals

25. Coelomates

26. Earthworm

27. Compare and Contrast Flatworm and Earthworm digestive tracts
One opening to flatworm’s digestive tract (pharynx)
Earthworm’s digestive tract has 2 openings (mouth and anus)

28. 3 types of worms Segmented Worms Roundworms Flatworms Phylum Annelida
Phylum Nematoda
Phylum Platyhelminthes
Segmented/sectioned bodies, bilateral symmetry
Bilateral symmetry
Bilateral symmetry, flat and thin bodies
Moist soil, freshwater, or saltwater
Wet soil or water
Parasitic- live inside a host or in water
Complete digestive tract- 2 openings (mouth and anus)
Complete digestive tract with 2 openings (mouth and anus)
One digestive opening (pharynx)
Coelomate- form from coelom (fluid filled space surrounded by mesoderm)
Pseudocoelomate- develop from 3 layers, with space between endoderm and mesoderm called Pseudocoelom
Acoelomate- develop from 3 layers but have no body cavities
Earthworms, leeches
Pinworms, hookworms
planarians, flukes and tapeworms