BI471 Parasitology Lab Practical #2

What are some common characteristics of Cestodes?

Cestodes are commonly known as tapeworms. They are endoparasitic and typically inhabit the gut (or small intestine) of vertebrates (fish, birds, mammals). They are known for the scolex, which can include structures like suckers and hooks. Their bodies contain a chain of segments known as proglottids. The proglottids nearest to the neck are known as immature proglottids. The next segment is the mature proglottid, which contains the fully formed and functioning reproductive organs. The last segment is the gravid proglottid, which contains eggs in addition to the reproductive organs. Typically, cestodes require at least two hosts to complete their life cycle. Lastly, they lack a digestive system and absorb nutrients across their neodermis (tegument). The neodermis is covered in sturcutes known as microtriches.

What species is this?

Diphyllobothrium latem. Scolex, w.m.

What is Diphyllobothrium latum known as?

Diphyllobothrium latum is known as the broad fish tapeworm. Its DH is usually a fish-eating carnivore, like a polar bear or human.

What species is this?

Diphyllobothrium latum. Mature proglottid, w.m.

How are eggs released from Diphyllobothrium latum?

Eggs are released from the uterine pore of the gravid proglottid while it is still attached to the strobila. The fate of these proglottids are best described as undergoing pseudoapolysis. D. latum does not have a genital pore whereas T. pisiformis does.

What species is this?

Diphyllobothrium latem. Eggs. Fecal smear.

Are D. latum eggs ready to hatch in the water?

No, these eggs need time to develop. They are distinguishable by the presence of their abopercular knob.

What species is this?

Taenia sp. Eggs. Smear.