Platyhelminthes Lab

Slides

Planaria

Class Turbellaria

Cross Section, 3 regions: 100x

 

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Whole Mount: 40x

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Fasciola hepatica

Class Trematoda

Whole Mount (w.m.): 40x

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“Animal Biology” by Internet Archive Book Images Under  Flickr

Cercariae: 400x

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Metacercariae: 400x

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Miracidia: 400x

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Rediae: 40x

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Clonorchis sinensis

Class Trematoda

Whole Mount: 40x

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Schistosoma

Class Trematoda

female: 40x

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male: 100x

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in copula: 100x

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Taenia pisiformis

Class Cestoda

scolex: 40x

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4 regions: 40x

 

mature proglottids: 40x

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Dipylidium caninum

Class Cestoda

composite w.m. (4 regions): 40x

 

Echinococcus granulosus

Class Cestoda

Adult: 40x

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Live

Planarians (Dugesia)

Class Turbellaria

Live Planarians: 40x

 

Digestive tracts of Turbellarians, Trematoda and Cestodes

Planarians have a three branched digestive track and they have more sense organs and a more complex brain than other turbellarians. Trematoda have the same body form and digestive cavity as the turbellarians.  Cestodes have no mouth or digestive system. Food is absorbed through the cuticle. The adults live in the digestive tract of vertebrates, and larval forms encyst in the flesh of various species. This demonstrates a parasitic adaption.

Reproductive Systems of Turbellarians, Trematoda and Cestodes

Planarians are able to regenerate entirely new individuals from small pieces cut from their body.  Almost the entire interior of trematoda is occupied by the reproductive system. They are capable of producing huge numbers of offspring. Cestodes are also mostly reproductive systems and they are also capable of having huge amounts of offspring.

Life-cycle of Trematodes vs. Cestodes

The life-cycle of Cestodes starts with the egg with a hexacanth embryo and then goes into the the larval stage. In the adult stage all cestodes usually require an intermediate host although in some species the definitive host can serve as intermediate host. The life-cycle of trematodes starts with the egg stage and then goes into the larval stages like the cestodes. A definitive host harbors the adult worm  and an intermediate host which is  usually a freshwater snail or mollusk harbors the larval stage. A second intermediate host such as a fish, crab, or another snail is required for encystment.

Terms

  • scolex: The anterior end of a tapeworm which has suckers and hooks for attatchment.
  • proglottid (immature, mature): Immature proglottids are the anterior most ones just behind the neck. They are shorter and broader and are devoid of reproductive organs. Mature proglottids occupy the middle part of the strobila and are a complete reproductive unit that produces eggs either by self-fertilization or cross-fertilization.
  • neck: This produces a chain of segments called proglottids through the process of strobilation.
  • testes and ovary: Individuals have both testes and ovaries which are used for reproduction.
  • oviduct: The tube that eggs pass through to get to the ovary.
  • gonopore: A genital pore in many invertebrates.
  • uterus: Where the fertilized egg implants and develops.
  • cysticercus: This is a larval tapeworm that is at a stage in which the scolex is inverted in a sac, and that is typically found encysted in the muscle tissue of the host.
  • oncosphere: The larval form of a tapeworm after it has been ingested by a host.
  • oral sucker and ventral sucker: There are usually oral suckers at the mouth and ventral suckers posterior to the mouth.
  • pharynx: Part of the digestive system that is divided into two parts.
  • acetabululm: A cup shaped sucker similar to a ventral sucker.
  • yolk glands: A special organ that secretes the yolk of the eggs.
  • miricidium: A small larval stage in the life of flukes.
  • sporocyst:  A larval stage in the life-cycle of flukes that originates from a miricidium.
  • rediae: A larval form with an oral sucker.
  • ceracaria: A free-swimming larval stage where the fluke  passes from an intermediate host to another intermediate host or to the final vertebrate host.
  • metaceraria: The encysted maturing stage of a trematode parasite in the tissues of an intermediate host.