1. Phylum Nematoda The Roundworms “thread” “like”

2. Characteristics of Nematodes
Level of Organization: Primitive Organ level
Symmetry: Bilateral
Complete ONE WAY digestive tube (separate mouth and anus!)
Simple nervous system with a nerve cord on it’s stomach (ventral)

3. Characteristics of Nematodes
Developed reproductive systems
Simple excretory system - excrete wastes through a pore
Sexes are separate (males and females), sexual reproduction
Cool fact: They are born with a certain number of cells that increase in size as they grow
Nematode cysts found on corn

4. Epidermis has a cuticle (made of collagen) to keep it from drying out
Longitudinal muscles
Many parasitic and free-living forms found in soil

7. Positive Roles of Free-living Nematodes
They are decomposers:
They recycle bacteria, fungi and decaying plants and animals back into the soil.
Very important to energy recycling on earth!

8. Negative Roles of Parasitic Nematodes
Invade many different types of crops can kill them
Attack the bark of forest trees
Invade the intestine of many mammals and cause sickness and death if untreated.
Soybean Cyst nematode: infects soybean plant crops and causes cysts on the plants

9. Parasitic Species of Nematodes include:
WHIPWORMS - invade the human large intestine - responsible for “Trichinosis”
HOOKWORMS - invade the small intestine of dogs, cats and humans - cause anemia as they suck blood
PINWORMS - invade the upper parts of the colon.
FILARIDS - invade many different parts of the body and are responsible for many diseases (including elephantiasis and Loa Loa)
ASCARIDS - invade the human intestine – responsible for Ascariasis

10. Example: Ascaris lumbricoides
Host infected accidentally by eating eggs in feces
Worms live in the digestive tract, and eggs are released again in the feces
Cool (gross?) fact:
Upon autopsy, a 2 year old South African girl was found to have 796 worms in her intestine

12. Example: Elephantiasis
Nematodes are transmitted by mosquitoes
They infect the lymph nodes
Causes thickening of the skin and tissues
More prevalent in tropical climates with over 120 million people affected worldwide