1. Flatworms Roundworms and Rotifers
Chapter 34
Flatworms Roundworms and Rotifers

2. Platyhelminthes-flatworms
 THREE CELL LAYERS (ecto-, meso-, and endoderm
Bilateral symmetry
THIN, FLAT BODIES
FLAT=PLATyhelminthes
NO RESPIRATORY SYSTEM
EXCHANGE GASES THROUGH THE SKIN
NO CIRCULATORY SYSTEM

3. Cephalization-a head is present
Ganglia-a cluster of nerve cells that serve as a brain to control the body
EYESPOTS-SENSE INTENSITY AND DIRECTION OF LIGHT

4. DIGESTION-ONE BODY OPENING WITH GASTROVASCULAR CAVITY
PHARYNX SECRETES DIGESTIVE ENZYMES OVER FOOD SOURCE AND ABSORB NUTRIENTS

5. REPRODUCE SEXUAL ASEXUAL-
HERMAPHRODITES, MALE & FEMALE CAN FERTILIZE EACH OTHER AT THE SAME TIME
ASEXUAL-
FISSION-THEY CAN SPLIT IN TWO, THEN REGENERATE THE MISSING PARTS

6. Class Turbellaria
FREE-LIVING FLATWORMS
EX: PLANARIANS

7. Class Trematoda-FLUKES
Parasites
Suckers attach to host and suck fluids
Tegument-protein and carbohydrate covering that protects from digestion
Reproduction-hermaphrodites
Schistosomes-flukes that cause disease called schistosomiasis
Parasites can penetrate skin when people are in contact with contaminated freshwater.
Eggs produced by females can accumulate in intestines or bladder
Causes inflammation or scarring
Swimmer’s itch also caused by flukes

8. Class Cestoda Parasites Tapeworms-
enter host when raw or undercooked meat is eaten
Infection may cause weight loss, lack of energy, and anemia
Structure:
Scolex (head)-hooks and suckers attach to host
Proglottids-repeating body sections that contain eggs that hatch when eaten

9. Phylum Nematoda-roundworms
Free-living or parasitic
Bilateral symmetry
Long-slender bodies
First animals to have 2 body openings
Separate sexes
Cuticle-Thick outer covering protects them from being digested

10. Class ascaris
Parasites-live in the intestines of pigs, horses, humans, etc
Can block intestines if untreated

11. Hookworms
Parasites
Cause anemia, slowed mental and physical development in children
Eggs released in feces; enter host by boring into the skin

12. Trichinella
Trichina worms live in intestines and form cysts in muscles
Infected by eating undercooked meat
Trichinosis-muscle pain and stiffness

13. Filarial worms cause elephantiasis

14. Pinworms Live in lower part of intestine
Females lay eggs around the anus