1. SBI 3U
Wormlike Animals

2. We are going to study… Platyhelminthes (flatworms)
Nematodes (roundworms)
Annelids (segmented worms)

3. Phylum Platyhelminthes
Flatworms
Acoelomates
Bilateral symmetry
Cephalization
True organs
Free-living and parasitic

4. Platyhelminthes – Free Living Flatworms
Small
“Blind” digestive system
Nervous tissue
Hermaphroditic
Ex: Planaria

5. Platyhelminthes – Parasitic Flatworms
Dependent upon host
Little sensory reception
Digestive system absent in some
Highly developed reproductive system
Example: Flukes and Tapeworms

6. Phylum Nematoda Roundworms Pseudocoelomates Complete digestive tract
Simple nervous system
No respiratory or circulatory system
Free-living & Parasitic

7. Phylum Nematoda: Parasitic Roundworms
Attack plants & animals
Some help humans
Ex: Ascaris

8. Phylum Annelida
Segmented worms
Coelomates
Ex: Earthworms

9. Earthworms and Ecology
Agriculture