BIOL113 L26
What are the general characteristics of flatworms?; Acoelomates with gastrovascular cavities, triploblastic, and range in size from nearly microscopic to over 20 m long.
How many species of flatworms are there, and in what habitats do they live?; About 20,000 species living in marine, freshwater, and damp terrestrial habitats.
What are some examples of parasitic flatworms?; Flukes and tapeworms.
What is the distinguishing feature of the flatworm's digestive system?; They have a gastrovascular cavity with only one opening.
What is the class of flatworms that are nearly all free-living and mostly marine?; Turbellaria.
How do planarians move?; Using cilia on the ventral epidermis and by gliding along a film of mucus they secrete.
What are the general features of parasites?; Structural and behavioral adaptations, specialized yet simplified, complex life cycles, and intermediate hosts and larval reproduction.
What is the role of an intermediate host in a parasite's life cycle?; It is an animal in which development occurs but in which adulthood is not reached.
What is the term for an animal harboring the adult or sexually mature stage of the parasite?; Definitive host.
What are the adhesive organs used for by trematodes and cestodes?; Attachment inside and outside the body of the host.
What is the purpose of sense organs being reduced in endoparasites?; Reduction in sense organs helps in adaptation to parasitic lifestyle.
How do trematodes and cestodes modify their nutrition?; They have modifications for direct absorption and storage areas.
What is the purpose of larval stages in the life cycle of parasites?; To allow the parasite to find different hosts.
What is the role of suckers in trematodes and cestodes?; They are used for attachment to their host.
What type of covering protects the trematodes and cestodes?; A tough covering protects these parasites.
What is the reproductive capacity of trematodes?; They have an increase in reproductive capacity, including asexual reproduction.
What is the purpose of larval stages in the life cycle of trematodes?; To allow the parasite to find different hosts.
What is the impact of Schistosoma infection on humans?; It infects 200 million people, leading to body pains, anemia, and dysentery.
Where do adult worms of Schistosoma live within the human body?; Within the blood vessels of the colon and urinary bladder.
Where is Paragonomiasis prevalent?; In the Far East, as well as areas in Central America and Africa.
How is Paragonomiasis transmitted to humans?; Through the consumption of raw freshwater crabs and crayfish containing the larvae (metacercaria) of Paragonimus.
What happens to the eggs of Paragonimus in fresh water?; They hatch as ciliated miracidia, which penetrate specific snails and multiply within.
How do the lung fluke larvae infect humans?; The consumed metacercaria penetrate the human small intestine wall and migrate to the lungs where they mate and live for a number of years, laying eggs which are expectorated or swallowed.
What are the symptoms of Paragonomiasis?; Lung abscesses, chronic cough, rusty colored sputum, and occasionally aberrant worms end up in the brain or subcutaneous tissues.
How can Paragonomiasis be prevented?; By cooking crab meat, implementing sewage treatment.
Where is Clonorchis sinensis prevalent?; In China.
How are liver flukes acquired by humans?; By eating infected freshwater fish.
What happens to the eggs of liver flukes in stool?; If they reach fresh water, they hatch as ciliated swimming miracidia.
How do the liver fluke larvae mature in humans?; They climb up the biliary tree and mature to adults in the intrahepatic biliary radicles, living for years and producing obstruction and abdominal pain.
What type of parasites are most monogeneans?; External parasites of fishes.
What kind of larva starts an infection on a host in the life cycle of monogeneans?; Ciliated, free-living larva.
What is the ciliated larva called in monogeneans?; Onchmiracidium.
Where do monogeneans usually occur on fish?; On either the skin or gills.
What is the example of a bladder parasite of frogs from Class Monogenea?; Polystoma integerrimum.
Where does Polystoma integerrimum live as a parasite?; In the bladder of the common frog.
What happens when the frog spawns in the case of Polystoma integerrimum?; It produces eggs.
Where are the larvae of Polystoma integerrimum attached?; To the internal gills of tadpoles (ectoparasite).
What happens when the tadpole metamorphoses into a frog in the case of Polystoma integerrimum?; Its gills reabsorb and the parasite passes down the gut of the frog to the urinary bladder.
Where do tapeworms (class Cestoidea) live mostly?; In vertebrates, including humans.
What anchors the tapeworm in the digestive tract of the host?; Suckers and hooks on the head or scolex.
What are released from the posterior end of the tapeworm and leave with the host’s feces?; Mature proglottids, loaded with thousands of eggs.
Where do tapeworm eggs in contaminated food or water develop into larvae?; In intermediary hosts, such as pigs or cattle.
How do humans acquire the larvae of the Hydatid tapeworm?; By eating undercooked meat contaminated with cysts.
What happens to the larvae of the Hydatid tapeworm within the human body?; They develop into mature adults.
What is the scientific name of the Hydatid tapeworm?; Echinococcus granulosus.
What is the method of transmission for the Hydatid tapeworm?; Through undercooked meat contaminated with cysts.
How many classes does the phylum Platyhelminthes consist of?; Four classes: Turbellaria, Monogenea, Trematoda, and Cestodea.
What are the characteristics of Trematodes?; They are usually leaf-shaped.
What is the size range of Platyhelminthes?; From microscopic to 100 ft long.
How are Platyhelminthes covered?; By a cytoplasmic tegument (vs cuticle).
Do Platyhelminthes have a body cavity?; No, they do not have a body cavity.
What is the nature of the digestive system in Platyhelminthes?; It is either absent or rudimentary.
Describe the excretory system of Platyhelminthes.; It contains ciliated cells extending into excretory tubules; in the living state, motion of cilia reminiscent of flames and indicates viability when seen under a microscope.
How do most species of Platyhelminthes reproduce?; Most species are hermaphroditic; adults reproduce sexually, while larvae can reproduce asexually.