5Phylum Nematoda Longitudinal muscles are used for locomotion Thrashing movements (can’t crawl like worms)
6Phylum Nematoda Sensory organs Amphids – chemoreceptors along the cuticlePhasmids - chemoreceptors near the anusOcelli – eyespots found in aquatic nematodes
7Feeding and Digestive System Carnivores, herbivores, omnivores, saprobes(decomposers), or parasitic Complete digestive system mouth->buccal cavity->pharynx ->tubular intestine->rectum->anus Hydrostatic pressure pushes food thru
8Other Organ Systems Glandular system Aquatic nematodes Renettes – absorb nitrogenous wasteTubular systemParasitic nematodesRenettes form a canal
9Other Organ Systems Nervous system Nerve ring from anterior to posteriorAlso have neuroendocrine secretions involved in growth, molting, cuticle formation, and metamorphisis
10Reproduction Sexual Dioecious-having separate sexes Dimorphic-males are smaller than femalesinternal fertilization
11Reproduction Males One testis Bursa- used to insert their sperm into the femalemales have ameboid sperm
12Reproduction Females Pair of convoluted ovaries Oviducts become uterus Several hundred to several hundred- thousand eggs per dayOvovivparity – giving birth to larvae that hatched from an egg
13Some Important Nematode Parasites of Humans Ascaris lumbricoidesEnterobius vermicularisNecator americanusTrichinella spiralisWuchereria bancrofti
14Ascaris lumbricoidesThe Giant Intestinal Roundworm- The adult female worm can be over 30 cm long and 2-6 mm wide 800 million infected- most common parasitic worm disease in the worldthe largest of the human intestinal nematodes. This is the most common parasitic worm disease in the world, very prevalent in tropical regions but rarely found also in our country. In the United States about 4 million people are infected. The adult female worm can be over 30 cm long and 2-6 mm wide. The female worm produces eggs per day.
15Ascaris lumbricoidesAdults live in small intestines of humans Eggs exit with through feces Once the eggs are ingested, they hatch in intestine and travel to the lungs Larvae molt twice, they travel to the trachea where they are swallowed
31Trichinella spiralisHumans become infected by eating improperly cooked pork products Larvae encyst in stomach move to small intestine molt 4 times, turn into Adults
32Wuchereria bancroftiThe Filarial worms In tropical countries over 250 million human infectedLymphatic vessels return tissue fluids to circulatory system
33Wuchereria bancroftiThread-like worms that live in the Lymphatic System, block the vessels This causes enlargement of various appendages: ElephantiasisAn Adult female Wuchereria bancrofti is about mm long and mm in diameter, whereas a male is about 40 mm long and 0.1 mm in diameter.
34ElephantiasisWarning: Pictures not for everyone!
35Wuchereria bancroftiAdults copulate produce microfilariae. The microfilariae released into the blood streamA microfilaria is about µm (micrometers) long and µm thick
36Wuchereria bancroftiMosquito (intermediate host) feeds on human (definitive host) ingest microfilariae and larvae molts 2 times Mosquito bites another human it injects 3rd stage larvae into human blood, molts, enters lymphatic system