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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
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
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