Transcript Lab
Lab Worms, worms & worms Class Turbellaria • planaria (Genus Dugesia) Planaria Planaria Asexual reproduction Class Trematoda Schistosoma mansonii male male female female Class Cestoida gravid proglottid scolex gravid proglottid tapeworm tapeworm cystericoids tapeworm oncospheres in muscle pinworm cystericoids tapeworm oncosphere Phylum Nematoda male is smaller, thinner & has a hooked end intestine Female Male intestine testes & vas deferens http://www.youtube.com/watch?v=_ybbnPj0t9Y • Enterobius vermicularis: human pinworm – – – – most common roundworm parasite in the US very common in children adults live in the lower region of the large intestine at night – gravid females migrate out of the cecum to the perianal area – deposit eggs – extreme itching – ingestion eggs continues the lifecycle • Necator americanus: the New World hookworm (found in southern US) – adults live in the small intestine – hold onto the intestinal wall with teeth – females may produce as many as 10,000 fertilized eggs per day which pass out through the feces – rhabditiform larva molts in moist soil to become the infective filariform larval stage – penetrates the skin of humans (between the toes) – symptoms: most individuals with hookworm infection are asymptomatic • pain in the stomach, pica (or dirt-eating), obstinate constipation followed by diarrhea, palpitations, unsteady pulse, coldness & pallor of the skin and mucous membranes • in cases running a fatal course - dysentery, haemorrhages and oedema. – hookworm prevalence is often higher among adult males • Ascaris lumbricoides: giant intestinal roundworm – 800 million humans worldwide may be infected – adults live in the small intestines of humans – penetrate the intestinal wall • generalized digestive disorders, such as a vague abdominal discomfort, nausea, colic. • may contribute to malnutrition in the host, • in heavy infections, the mass of worms may block the intestine and need to be surgically removed. – produce large numbers of fertilized eggs that exit with the feces – can be carried via the circulation to the lungs – molt twice, travel up the trachea and are swallowed • may lead to breathing difficulties, pneumonia and/or fever. • easily treated with a number of anthelmintic drugs • Trichinella spiralis: porkworm – adults live in the mucosa of the small intestine of omnivores like pigs – in the intestine, the female gives birth to larvae that are carried to skeletal muscle – the young larvae encyst in the muscle and remain infective for many years – eaten by humans • causes the disease trichonosis • symptoms: • fever • muscle soreness & pain • swelling around the eyes • Chest pain - parasite may become imbedded in the diaphragm • incubation period: 10 to 45 days • treatment: anti-helminthetic drugs • mebendazole, thiabendazole • Wuchereris species: filarial worms – tropical countries – over 250 million humans infected – transmitted by mosquitos – larvae are threadlike in structure & live in the lymphatic system of humans – clog up lymphatic vessels and block the return of lymph to the CV system – results in an accumulation of fluids in the peripheral tissues – can result in extremely enlargened appendages known as elephantitis • in the U.S Dirofilaria immitis – lives in the large arteries of the heart and lungs of dogsheartworm Phylum Annelida • Class Polychaeta – bristle worms – – – – – – e.g. Nereis marine worms possess parapodia with setae brightly colored – many are luminscent range from plankton to burrowing species found in all marine temperatures • Class Oligochaeta: marine and terrestrial worms – e.g. earthworms – Lumbricus • 700 species – native to Europe, invasive in North America – many lack parapodia and setae • Class Hirudinea: leeches Class Polycheata Eunice pennata Hermodice carunculata X-mas tree worm Class Polycheata Class Oligochaeta Lumbricus Class Oligochaeta (stomach) http://www.youtube.com/watch?v=zkSghTbgIjs Class Oligochaeta Class Oligochaeta metanephridia seminal vesicles intestine pharynx ventral nerve cord ventral blood vessel lateral nerves hearts dorsal blood vessel intestine intestine metanephridia crop & gizzard (Stomach) stomach seminal vesicles hearts