Lab

Worms, worms & worms

Class Turbellaria

• planaria (Genus Dugesia)

Planaria

Asexual reproduction

Planaria

Class Trematoda

female

male

female

male

Schistosoma mansonii

Class Cestoida

scolextapeworm

gravid proglottidgravid proglottid

tapeworm oncospheresin muscle

pinworm cystericoids

tapeworm cystericoids

tapeworm oncosphere

Phylum Nematoda

male is smaller, thinner & has a hooked end

intestine

http://www.youtube.com/watch?v=_ybbnPj0t9Y

intestine

testes & vas deferens

Female

Male

• 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

X-mas tree wormHermodice carunculata

Eunice pennata

Class Polycheata

Class Oligochaeta

Lumbricus

Class Oligochaeta

(stomach)

http://www.youtube.com/watch?v=zkSghTbgIjs

Class Oligochaeta

Class Oligochaeta

hearts

dorsal blood vessel crop & gizzard(Stomach)

pharynx

metanephridia seminal vesicles

intestine intestine seminal vesiclesstomach

hearts

metanephridia

intestine

ventral nerve cordventral blood vessel

lateral nerves