1. Nematoda

2. Phylum & Sample Animals
Phylum: Nematoda
Classes: Adenophorea, Secernentea
Sample Animals:
Caernorhabditis elegans
a model organism for research – human aging.
Trichinella Spiralis
Ingesting infected pork
Invades muscle cells and control it

3. Body Cavity
Pseudocoelom: It has a body cavity only partially lined by tissue derived from mesoderm.

4. Nervous System Nematodes have a simple nervous system
main ventral nerve cord
and
a smaller dorsal nerve cord.

5. Digestive System Nematodes have a digestive system
separate sites for food intake.
Those that are free-living (not parasitic)
Digest dead matter, returning usable nutrients to soil or marine environment

6. Locomotion/musculature
Movement due to longitudinal muscles that when contracted produced a thrashing motion.

7. Skeletal Type Nematodes have a hydrostatic skeleton.
The pressure from the pseudocoelom and the muscles change an organism’s shape and produce movement.

8. Body Structure

9. Reproductive system Usually sexual. Involves internal fertilization.
Females…100,000 fertilized eggs per day!
Zygotes are resistant cells and can survive harsh conditions.

10. Gas Exchange Gas exchange occurs through diffusion.
Some parasitic nematodes have a form of hemoglobin in the body fluids.
Anaerobic and Aerobic metabolism is also common.

13. Hookworms, Pinworm & Filarial worm
Elephantiasis

14. Questions
How do the nematoda use there musculature for motion differently from the others?
What is the skeletal system called? What does this mean?
Why are some nematodes called “animals that act like viruses”?
Which type of symmetry do nematodes exhibit? How can you tell?

15. Answers
Nematoda have longitudinal muscles that they contract rapidly and create a thrashing motion.
They have hydrostatic skeletal systems that react to the environment and the pressure that is exerted upon them
Some have learned to control the muscles of humans in order to receive the nutrients they need to survive.
The nematodes have radial symmetry that can be proven by the fact that they can be cut anyway through the central axis to create mirror images.