BIOLOGY 11 Kingdom Animalia Phylum Nematoda The Roundworms

BIOLOGY 11 Kingdom Animalia: Phylum Nematoda: The Roundworms

Phylum Nematoda Objectives • Advances over Platyhelminthes • Body plan and body systems • 2 broad types and their example animals • Parasitic worms (enter, live, hosts, effects)

The Pseudocoelomates Characteristics and Advances 1. Evolution of the anus allows for a complete digestive system - tube within a tube body plan 2. A pseudocoelom between mesoderm and endoderm

Phylum Nematoda The Roundworms • A very large phylum found in almost all habitats • most are small to microscopic • Reproduction is mostly sexual Hookworms

Phylum Nematoda A. Free living nematodes • Most nematodes live in water or soil • They are important in the ecology of soil decomposers A Soil Nematode

Phylum Nematoda B. Parasitic Nematodes Some of the worst worm parasites are members of this phylum 1. Ascaris sp. the Intestinal Roundworm • Most common world wide worm parasite - over 1 billion people have it • Lives in small intestine but travels through the body as a juvenile

Phylum Nematoda 2. Hookworm • Human hookworm (Necator sp. ) feeds on blood from inside of intestine • A single worm can drain 20 ml of blood per day • Most serious in children as can lead to physical and mental retardation • Enters as “Itch worm” between toes

Phylum Nematoda 3. Pinworm (Enterobius sp. ) • Lives in lower bowel • Female migrates out anus each night to lay eggs • Secretes irritating toxin to get person to scratch • Re-infection is oral

Phylum Nematoda 4. Trichinella • From eating undercooked pork • Invades selected muscles forming painful cysts • Causes Trichanosis

Phylum Nematoda 5. Filarial Worm • Small nematode that lives in human lymph ducts and blocks them • As a result, fluids can’t drain so accumulate resulting in severe, grotesque swelling below Causes Elephantiasis where the worm is

Phylum Nematoda 6. The Guinea Stick Worm (Dracunculus sp. ) • In Africa only • Enters while a person is in contaminated water and burrows through skin and grows • No cure - is removed by wrapping around a stick - one turn per day • Contains deadly toxin if broken it can kill its victim