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Phylum Nematoda. Roundworms Means “Thread”. Aaugh! They are Everywhere!. Every fist-full of dirt Every rotten apple Each square meter of lake bottom Most are free living Most are parasites. Nematooooda!.
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Phylum Nematoda Roundworms Means “Thread”
Aaugh! They are Everywhere! • Every fist-full of dirt • Every rotten apple • Each square meter of lake bottom • Most are free living • Most are parasites
Nematooooda! • One study in Colorado estimated that nematodes consumed about as much grass as a prairie dog colony.
Characteristics • Tough outer covering- Cuticle • No circular muscles- run lengthwise (move with a crazy thrusting movement) • Smooth, round, nonsegmented • Tube within a tube • Separate sexes • 15,000 known species
Examples • Hookworm- • Sucks blood in intestine • Enters between the toes by boring in the skin
Filaria • Causes Elephantiasis • Transfer by mosquito
Trichinella • Causes trichinosis • Found in pork
Pinworm • Common among children • Intense rectal itching • Worms are visible near the anus at night or early in the morning
Horsehair Worm • Parasites on grasshoppers, crickets, locusts, katydids, and beetles • Other hosts include dragonflies, spiders, millipedes, centipedes, and leeches
Persistent • Many nematodes are able to suspend their life processes completely when conditions become unfavorable; in these resistant states they can survive extreme drying, heat, or cold, and then return to life when favorable conditions return.