1. Worms

2. Flatworms Bilateral symmetry No coelum Has organs & systems
3 body layers
Ectoderm
Mesoderm
Endoderm
Gasses pass in/out by diffusion
Anterior end (front) w/ mouth
Primitive brain

3. Flatworm Reproduction
Asexual
Stretch are break apart
Each half becomes new animal
Sexual
Hermaphrodites
Both transfer sperm to one another
Web link

4. Flatworm Parasites Tapeworms Flukes
Larvae enter through undercooked meat
Hooks attach to inner walls of intestines
Food absorbed through skin
Grow up to 12 meters
Flukes
Internal or external parasites
Contain protective layer to prevent from being digested
Ex: Schistosomiasis

6. One Final Look

7. Roundworms Cylindrical bodies w/ mouth and anus Separate male/female
Sexual reproduction
1st to have body cavity (coelum)
Movement of fluid circulates gas & nutrients
Most small in size (few mm)
Most free-living

8. Roundworm Parasites Ascaris Infects pigs, horses, humans
Knots of worms can block intestines (cause death)
Larvae cause respiratory illness
Females: lay 200,000 eggs/day
Trichinella
Eat undercooked pork
Larvae burrow into intestines & mature
New larvae pass into blood & form cysts in muscles

10. Segmented Worms Have coelum Several organ systems
Complex digestive system
Circulatory sys: 2 blood vessels
Nervous sys: Primitive brain and nerve cord
Muscular sys: Circular & longitudinal muscles
Gas exchange through skin

11. Segmented Worm Reproduction
Hermaphroditic
Ventral surfaces press together
Mucus holds worms together
Sperm released into the mucus & stored in a pouch
Worms develop inside pouch

12. Segmented Leeches Live in calm, freshwater
Sucker attached to host or prey
Release anaesthetic to hide presence
Can eat up to 10x own weight
Used to help restore blood flow in limb reattachment