18 Questions
What is the specialized head region of tapeworms called?
Scolex
Which class includes the common liver fluke Fasciola hepatica?
Class Trematoda
What is the length of the specimen of the giant liver fluke Fascioloides magna shown?
7 meters
What are the segments known as in the body of tapeworms?
Proglottids
Which type of flatworm latches onto the gills with anchors?
Gill fluke
What is the length range that Taenia saginata, a tapeworm, can reach?
2 - 4 meters
What is the Greek word 'nema' that is associated with the term 'nematode'?
Thread
Which characteristic is unique to roundworms (nematodes) among other helminths?
Complete digestive system
In which habitats can parasitic helminths commonly be found?
Intestinal tracts
What is the main difference in body shape between flatworms and roundworms?
Flatworms are covered with plasma membrane, roundworms are covered with cuticle
Which part of the digestive system of nematodes is responsible for digestion?
Pharynx
What is the term used to describe organisms that are both male and female in terms of reproduction?
Monoecious
Which of the following is NOT an area commonly affected by ringworm?
Arms
Which nematode infection is the most common in the United States?
Enterobius vermicularis
How do trematodes differ from tapeworms?
Trematodes have an oral sucker while tapeworms do not
What is the primary mode of transmission for Enterobius vermicularis?
Hand to mouth transfer of infective eggs
What is the second most impactful parasitic disease on human populations after malaria?
Schistosomiasis
Which class includes flatworms like flukes and tapeworms?
Class Trematoda
Study Notes
Parasitic Flatworms
- Class Monogenea includes Dactylogyrus spp., commonly called gill flukes, which latch onto gills using anchors.
Class Trematoda (Parasitic Flatworms)
- Includes the common liver fluke Fasciola hepatica and the giant liver fluke Fascioloides magna.
Class Cestoda (Tapeworms)
- Tapeworms are segmented flatworms that inhabit the small intestine of their definitive host.
- Features a specialized head region called the scolex, which may feature suckers or hooks for attachment to the intestinal wall.
- The body of the tapeworm is comprised of segments called proglottids, which contain reproductive structures.
- Each proglottid contains both male and female reproductive organs, allowing tapeworms to produce eggs for reproduction.
General Characteristics of Parasitic Helminths
- Often studied in microbiology due to identification via microscopic eggs and larvae.
- Two major groups: Roundworms (Nematoda) and flatworms (Platyhelminthes).
- Around half of species in these groups are parasitic; some are significant human pathogens.
- Multicellular organisms with organ systems; parasitic species often have limited digestive tracts, nervous systems, and locomotor abilities.
Characteristics of Nematodes (Roundworms)
- Contain over 15,000 species.
- Have a complete digestive system divided into three parts: stomodeum, intestine, and proctodeum.
- Males are smaller than females and have a bent tail for holding the female for copulation.
- Have an outer covering called cuticle.
Areas Affected by Ringworm
- Feet (tinea pedis, commonly called "athlete's foot")
- Groin, inner thighs, or buttocks (tinea cruris, commonly called "jock itch")
- Scalp (tinea capitis)
Enterobius Vermicularis
- The most common helminth in the United States.
- Causes household and institutional epidemics, usually in children.
- Transmission is usually by hand-to-mouth transfer of infective eggs.
Platyhelminths (Flatworms)
- Includes flukes, tapeworms, and turbellarians (including planarians).
- Flukes and tapeworms are medically important.
Trematodes (Flukes)
- Nonsegmented flatworms with an oral sucker.
- Have complex life cycles, often with multiple hosts.
- Examples include liver flukes (Opisthorchis, Clonorchis), intestinal fluke (Fasciolopsis buski), and Oriental lung fluke (Paragonimus westermani).
Schistosomiasis
- A serious parasitic disease, considered second in impact on human populations only to malaria.
- Caused by Schistosoma mansoni, S.haematobium, and S.japonicum, which are found in freshwater snails.
Test your knowledge on the parasitic flatworm classes Monogenea and Trematoda. Learn about Dactylogyrus spp., gill flukes, Fasciola hepatica, and Fascioloides magna.
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