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Phylum Nematoda (roundworms). 12,000 spp. free-living & parasitic ubiquitous important in medicine and horticulture. Morphology. slender, elongate, & most <2.5mm cuticle containing collagen longitudinal muscles only - producing eel-like undulations
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Phylum Nematoda (roundworms) • 12,000 spp. • free-living & parasitic • ubiquitous • important in medicine and horticulture
Morphology • slender, elongate, & most <2.5mm • cuticle containing collagen • longitudinal muscles only - producing eel-like undulations • circumpharyngeal nerve ring and longitudinal nerve cords
Reproduction & Development • dioecious • hermaphrodites • egg storage in the uterus • may produce 200,000 eggs/day • protostomes
16% adults & 30 % children in US are infected female deposits eggs at night in the perianal region complex life cycle Enterobius - “pinworm”
Necator – “hook worm” • mouth parts are designed to bite onto the lining of the intestine, abrade the surface and suck the patients blood. • many people show no outward symptoms of disease. • the severity of the disease depends on the number of worms per individual, the nutritional state of the patient and the species of hookworm
causes trichinosis acquired by eating undercooked pork larvae encyst in host muscle tissue Trichinella
afflicts ~ 100 million and is said to be one of the world’s fastest spreading diseases the parasite clogs the lymph vessels of the host. Wuchereria – causes elephantiasis