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24 Cards in this Set
- Front
- Back
What organisms make up Phylum Platyhelminthes?
What organism makes up Phylum Nematoda? |
Flatworms
Roundworms |
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Both phylum Phlatyhelminthes & Nematoda occur in?
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Marine, Freshwater, Terrestrial & parasitic environments.
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Define Acoelomate
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Mesoderm is a solid mass of tissue with no internal cavity surrounded by mesoderm. (no spacious cavity for internal organs)
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Define Triploblastic
Are flatworms & roundworms triploblastic? |
Organism contains all 3 germ layers ( endoderm, ectoderm & mesoderm).
Yes, flatworms & roundworms are triploblastic. |
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What type of symmetry do roundworms & flatworms have?
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Bilateral symmetry.
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Key characteristics of Phylum Platyhelminthes
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solid, unsegmented, bilaterally symmetrical worms; no body cavity, digestive cavity, if present, has only one opening, ladderlike arrangement of nerve cords.
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What classes make up Phylum Platyhelminthes?
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Class Turbellaria, Class Trematoda & Class Cestoda
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Class Turbellaria
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Scavenge & prey on small animals & are hermaphroditic
( has both male & female sex organs) . |
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Dugesia (planaria)
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found under class turbellaria. has lateral lobes & sensory organs (eyespots), feeds by sucking food through mouth & tubular pharynx, acoelomate & digestion is usually extracellular.
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Class Trematoda
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Commonly called flukes, are parasitic & infect vertebrates. Includes endoparasites (parasites inside the host) & ectoparasites (parasite on the surface of the host).
Lack an epidermis & covered by an acellular but metabolically active epicuticle. |
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Opisthorchis
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Found in Class Trematoda. A hermaphroditic chinese liver fluke, often parasitizes humans in Japan & China. Adult fluke attaches to the bile duct & releases eggs that move through digestive sys. of host & exist with feces. Larvae of flukes develop in snails & fish. Humans are infected when they eat raw or poorly cooked fish.
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Fasciola
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Found under Class Trematoda. A sheep liver fluke, infects sheep, other vertebrates & rarely humans. Fasciola sucks food ( blood, mucus, cells) through a muscular pharynx located behind the mouth.
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Schistosoma
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Found under class trematoda. A diocious blood fluke, inhabits intestinal veins & organs of vertebrates. Causes disease schistosomiasis ( enlarged spleen, liver & bladder). Snails are intermediate hosts.
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Intermediate host
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An organism harboring immature stage of a parasite.
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Definitive host
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Contains sexually mature, egg-laying stages of a life cycle.
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Class Cestoda
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Commonly called tapeworms, endoparasites, lack a mouth, digestive tract, & similar cuticle to trematodes, cuticle absorbs nutrients from host.
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Scolex
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Anterior end of a tapeworm. Adheres to the hosts intestinal wall with hooks or suckers. Behind the scolex is the neck followed by a series of proglottids.
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Gravid
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Egg-carrying proglottids.
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Key Characteristics of Phylum Nematoda
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Pseudocoelomate, unsegmented, bilaterally symmetrical worms; tubular digestive tract passing from mouth to anus;tiny; without cilia; live in great numbers in soil & aquatic sediments; some are important in animal parasites.
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Elephantiasis
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Grotesque swelling of an arm or leg resulting from nematodes (commonly Filaria) clogging the lympathic system that drains the host's appendage, fluid accumulates & appendages swell.
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Pseudocoelom
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Body cavity consisting of a fluid-filled space between the body wall & digestive tract.
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Complete Digestive Tract
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Digestive tract with a mouth and anus.
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Ascaris
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A large nematode that infects the intestinal tract of humans & other vertebrates.
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Trichinella
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Trichinella spiralis causes the disease trichinosis. Adults live in the intestine of their host & release larvae, the larvae migrate to striated muscles & form calcified cysts. Larvae remain encysted in muscle tissue until eaten by another host.
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