ROUNDWORMS Kingdom Animalia Phylum Nematoda Unsegmented worms Pseudocoelom

ROUNDWORMS Kingdom Animalia Phylum Nematoda • Unsegmented worms • Pseudocoelom ("false coelom") • body cavity contains organs

Digestive tract with 2 openings: mouth & anus Feeding Free-living - predators Parasites - humans and animals Reproduction Sexual reproduction, Diecious - separate sexes (male & female)

Roundworms & Disease Trichinosis (caused by the 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 • heartworms are filarial

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 come from soil • mature in the intestines • hooks used to attach and suck blood

Pinworms or Threadworms • Ingested from hands, contaminated food or rarely water • Fecal contamination and oral ingestion. • 2 -4 week life cycle.

Beneficial in Gardens • Some nematodes parasitize grubs and larva of insects that damage crops and lawns.

Research on C. elegans • first organism to have DNA completely sequenced • It is a very simple, free living roundworm