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Questions and Answers
What is a defining characteristic of the class Cestoda?
What is a defining characteristic of the class Cestoda?
Which class of Platyhelminthes usually lives as an ectoparasite on fish?
Which class of Platyhelminthes usually lives as an ectoparasite on fish?
What is the function of the ventral cilia in most species of Platyhelminthes?
What is the function of the ventral cilia in most species of Platyhelminthes?
How does the tegument of Cestoda differ from that of other flatworms?
How does the tegument of Cestoda differ from that of other flatworms?
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What is the larval stage of Monogenea called?
What is the larval stage of Monogenea called?
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What feature allows some Monogenea to exhibit high specificity for their host?
What feature allows some Monogenea to exhibit high specificity for their host?
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Which characteristic is not associated with the class Trematoda?
Which characteristic is not associated with the class Trematoda?
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What is the primary habitat of Cestoda?
What is the primary habitat of Cestoda?
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Which class of Platyhelminthes contains free-living flatworms?
Which class of Platyhelminthes contains free-living flatworms?
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What is the primary method of gas exchange in Platyhelminthes?
What is the primary method of gas exchange in Platyhelminthes?
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Which subclass of Cestoda includes the true tapeworms?
Which subclass of Cestoda includes the true tapeworms?
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What unique feature is common to most platyhelminths regarding their reproductive system?
What unique feature is common to most platyhelminths regarding their reproductive system?
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What role do protonephridia play in Platyhelminthes?
What role do protonephridia play in Platyhelminthes?
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What is a significant characteristic of the phylum Platyhelminthes?
What is a significant characteristic of the phylum Platyhelminthes?
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Which of the following classes of Platyhelminthes typically contains species that are most commonly marine?
Which of the following classes of Platyhelminthes typically contains species that are most commonly marine?
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What is the function of parenchyma tissue in Platyhelminthes?
What is the function of parenchyma tissue in Platyhelminthes?
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Study Notes
Phylum Platyhelminthes Summary
- Platyhelminthes are a phylum of flatworms
- Members of this phylum are primarily free-living, or parasitic
- The most prominent feature of platyhelminths is their flattened shape
- They lack specialized respiratory and circulatory systems
- Gas exchange occurs via simple diffusion across the body surface
- Metabolic wastes primarily diffuse across the body surface
- Specialized organs called protonephridia are responsible for removing metabolic wastes like ammonia, urea, and amino acids
- Osmoregulation is achieved through protonephridia
- Most platyhelminth species are simultaneous hermaphrodites
Platyhelminthes Classes
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Class Turbellaria:
- About 6% of all flatworm species are turbellarians
- Predominantly free-living
- Primarily inhabit marine, freshwater, and terrestrial environments (humid)
- Mostly less than 1cm in length
- Most aquatic turbellarians are benthic, living on the ocean, lake, pond or river bottom
- Have a ciliated outer body surface, especially on the ventral side
- Movement is often via mucus secretion with cilia movement within the mucus
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Class Cestoda:
- Members of this class are primarily endoparasitic
- Commonly known as tapeworms
- Composed of proglottids, segments that develop from the anterior end
- Characterized by a scolex, an anterior hooked attachment organ
- The vast majority of species are simultaneous hermaphrodites
- Usually inhabit various regions of the host's digestive tract
- Contain numerous nuclei within the tegument, separated by cell membranes(syncytial)
- The outer surface of the tegument is out folded into cytoplasmic projections, greatly increasing exposed surface area for nutrient absorption
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Class Monogenea:
- Monogenetic flatworms are typically ectoparasites, residing on the skin or gills of fishes
- Show a high degree of host specificity and reside in specific host sites
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Class Trematoda:
- Trematodes have a mouth opening and a blind-ended digestive tract, typically bilobed
- Tegument is unciliated and syncytial
- Body is not segmented
- Parasites that ingest host tissue and blood (e.g. Schistosomiasis blood flukes)
Defining Characteristics of Different Classes
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Class Cestoda:
- Small anterior hooked attachment organ (scolex)
- Body divided into segments (proglottids) arising from anterior end
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Class Trematoda:
- Posterior attachment organ (haptor)
- Larval stage (oncomiracidium) bearing 3 bands of cilia.
- Typically bearing 1 or 2 pairs of eyes.
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Class Monogenea:
- Mostly parasitic on the skin or gills of fish.
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Description
Explore the fascinating world of Phylum Platyhelminthes, or flatworms, known for their distinct flattened shape and lifestyle. This quiz covers their characteristics, classes, and modes of living, including both free-living and parasitic species. Test your knowledge on their anatomy and adaptations in various environments.
