Lab

Worms, worms & worms

Class Turbellaria

• planaria• dugesia

Planaria

Asexual reproduction

Dugesia

Class Trematoda

female

male

female

male

Class Cestoida

scolextapeworm

tapeworm oncospheres

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

• 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 the southern US– adults live in the small intestine – hold onto the intestinal wall with teeth– feed on blood and tissue fluids– females may produce as many as 10,000 fertilized eggs per day which pass out through the

feces– egg hatches in warm, moist soil and releases a small larvae called the rhabditiform larva– this larva molts to become the infective filariform larval stage – penetrate the skin of humans

(between the toes)– burrows into the circulatory system– symptoms: most individuals with hookworm infection are asymptomatic

• very high loads of the parasite or poor nutrition combined with infection lead to anemia.– pain in the stomach, pica (or dirt-eating), obstinate constipation followed by diarrhea,

palpitations, small and unsteady pulse, coldness of the skin, pallor of the skin and mucous membranes, diminution of the secretions, loss of strength and, 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

• generalised 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

• migration of larvae through the lungs can give rise to severe haemorrhagic pneumonia. • may lead to breathing difficulties, pneumonia and/or fever.

• Infections with A.lumbricoides are easily treated with a number of anthelmintic drugs– levamisole, mebendazole, albendazole

• 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: usually start with fever, muscle soreness, pain and swelling around the eyes. Thirst, profuse

sweating, chills, weakness and tiredness may develop. Chest pain may be experienced since the parasite may become imbedded in the diaphragm (the thin muscle separating the lungs from abdominal organs).

– incubation period: 10 to 45 days– treatment: 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– tend to clog up lymphatic vessels and block the return of

lymphatic vessels 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 a filarial worm – Dirofilaria immitis – lives in the large arteries of the heart and lungs of dogs - heartworm

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 worm

plankton polycheate

Hermodice 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

Class Oligochaeta

intestine seminal vesiclesstomach

hearts

Class Oligochaeta

metanephridia

intestine

ventral nerve cordventral blood vessel

lateral nerves