ROUNDWORMS Kingdom Animalia - Phylum Nematoda --Pseudocoelom ("false coelom") -- Digestive system has two openings with mouth and anus.

Interesting Facts About Nematodes Prevalence: They are the most numerous of all multicellular animals. Ecological Significance: They are found in nearly all parts of the earth and are an important part of food chains and soil health. Parasite Success: ¼ of the world is infected with hookworm! (a roundworm intestinal parasite)

Similarities to Platyhelminthes Bilateral Symmetry What is bilateral Symmetry? What might be one advantage? Cephalization What is cephalization? What might be an advantage?

Roundworms & Disease 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

Filarial Worms - found in Tropical regions of Asia -- usually transmitted by mosquitoes -- causes elephantiasis

Ascarid Worms (common roundworm) - lives in intestine - eggs are passed out in the feces Most roundworms infect dogs, but occasionally they find their way into human hosts

Hookworms - burrow into the skin from soil - mature in the intestines --hooks used to attach and suck blood

Research on C. elegans (MODEL ORGANISM) first organism to have DNA completely sequenced It is a very simple, free living roundworm They have a fixed number of cells, which is very useful to learn about development. You can track the history of every cell in the body!