1. Introduction to Nematoda (Roundworms)
Biology 11
Mrs. Trevelyan

2. Nematoda 1. PRESCRIBED LEARNING OUTCOMES and VOCABULARY 2. VIDEOS:
None 
3. TEXTBOOK PGS
Section 26.3 pgs

3. Overview…

4. Picture Warning- Graphic Images

5. Examples of Members:

6. 1. Unifying Characteristics
Bilateral symmetry, no segmentation
Some free living, most parasitic on animals (humans too!)
Pseudocoelom (false coelom)
Body “cavity” contains organs
Has 2 openings- a separate mouth and anus
Has a 1-way digestive tract
Ends of body “taper” off
No skeleton, circulatory or respiratory systems
Sexual reproduction with separate male and female

7. 2. Structure Cephalisation with tapered ends
Has 3 cell layers and a pseudocoelom
Development of more complex tissues and organs (e.g. mouth, pharynx, intestine, rectum, anus, etc)

8. 3. Digestion two openings Free-living are carnivores
Parasitic flatworms anchor themselves to their host and live off of host tissue/blood

9. 4. Respiration/Excretion
No Respiratory organs
Exchange gases by diffusion
EXCRETION
Solid wastes exit the body through the anus
liquid wastes exit the body through excretory pore

10. 5. Nervous System More advanced than flatworms
Have a ring of nerve tissue around the pharynx
Has 2 nerve cords (dorsal and ventral)
Some sensory projections on head

11. 6. Reproduction Roundworms usually have separate male and female
Reproduce sexually
Internal fertilization, female keeps fertilized eggs in uterus until laid
Some species, like Ascaris,
can lay 200, 000 eggs a day!

12. Roundworms and Disease
1. Trichinosis (trichinella worm)  - cysts within the muscles are consumed (undercooked food)  - worm grows in intestine - forms cysts in the muscles of the new host  - symptom: terrible pain in muscles

13. Roundworms and Disease
2. Filarial Worms - found in Tropical regions of Asia - usually transmitted by mosquitoes - causes elephantiasis
3. Ascarid Worms (common roundworm)  - lives in intestine - eggs are passed out in the feces

14. Roundworms and Disease
4. Hookworms
- burrow into the skin from soil - mature in the intestines -hooks used to attach and suck blood

15. Can humans get roundworms from their pets?