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SYSTEMATICS > Platyhelminthes > Flashcards

Platyhelminthes Flashcards

1
Q

Two major evolutionary advances of plathyhelminthes

A

⚬ Cephalization
⚬ Primary bilateral symmetry

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2
Q

General Features of plathyhelminthes

A
  • Mesoderm well-defined
  • Triploblastic
    *Highly specialized parasites
  • Some argue this group were derived from complex
    free-living organisms
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3
Q

having a body derived from three embryonic cell layers

A

Triploblastic

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4
Q

the concentration of sense organs, nervous control, etc., at the anterior end of the body, forming a head and brain, both during evolution and in the course of an embryo’s development.

A

Cephalization

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5
Q

Typical animals that have only one internal space, the digestive cavity

A

Acoelomates

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6
Q
  • Commonly called flatworms
  • Vary from a millimeter to many meters in length
  • Some free-living; others parasitic
A

Phylum Platyhelminthes

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7
Q

Platyhelminthes is divided into four classes:

A

Class Turbellaria
Class Trematoda
Class Monongenea
Class Cestoda

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8
Q

Class
⚬ Mostly free-living
⚬ Range from 5 mm to 50 cm long
⚬ Except for polyclads
Simple gut or no gut and a simple pharynx

A

Class Turbellaria

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8
Q

free-living in Class Turbellaria Except for

A

polyclads, endolecithal
turbellarians

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9
Q

Class Turbellaria organisms that have a folded pharynx and a gut with many branches

A

Polyclads

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10
Q

Class Turbellaria is a Member of

A

Tricladidia

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11
Q

are parasitic flukes
Most adults are endoparasites of vertebrates
They resemble ectolecithal turbellaria but the tegument lacks cilia in adults
Sense organs are poorly developed

A

Class Trematoda

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12
Q

Adaptations for Class Trematoda parasitism include:

A

⚬ Hooks and suckers for adhesion
⚬ Increased reproductive capacity

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13
Q

Phylum Platyhelminthes
* Adult fluke lives in bile passageways in the liver of sheep and other ruminants
* Eggs are pass out in feces

A

Fasciola hepatica (Sheep Liver Fluke)

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14
Q

Phylum Platyhelminthes
In Fasciola hepatica (Sheep Liver Fluke), the ____ hatch and penetrate snails to become sporocysts

A

Miracidia

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15
Q

two generations of rediae

A

Cercaria
metacercariae

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16
Q

stage that encyst on vegetation and await being eaten by sheep in Fasciola hepatica (Sheep Liver Fluke),

A

Cercaria

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17
Q

stage that develop into young flukes
in Fasciola hepatica (Sheep Liver Fluke),

A

metacercariae

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18
Q

Phylum Platyhelminthes
* Most important human liver fluke
* Common in China, Japan, and Southeast Asia
* Also infects cats, dogs, and pigs
* Adult fluke is 10–20 mm long with an oral and ventral sucke

A

Clonorchis sinensis: Chinese Liver Fluke

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19
Q

Clonorchis Life Cycle

A
  • Adults live in bile passageways of humans and other fish-eating mammals
  • Eggs containing a complete miracidium are shed into water with feces
  • The eggs hatch only when ingested by snails of specific genera
  • Miracidium enters snail tissue and transforms into a sporocyst
  • Sporocyst produces one generation of rediae, which begin differentiation
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20
Q

Phylum Platyhelminthes
Over 200 million people infested with schistosomiasis
Common in Africa, South America, West Indies, and the
Middle and Far East
* Sexes are separate

A

Schistosoma: Blood Flukes

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21
Q
  • 3 species account for most human schistosomiasis
A

⚬ S. mansoni in venules of large intestine
⚬ S. japonicum in venules of small intestine
⚬ S. haemotobium in venules of urinary bladder

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22
Q

Schistosoma Life Cycle

A
  • Eggs discharged in human feces or urine
    *In water, eggs hatch as ciliated miracidia
  • Must contact a particular species of snail to survive
    *In the snail, they transform to sporocysts
  • Sporocysts produce cercaria directly
  • Cercariae escape the snail and swim until they contact bare human skin
  • Cercariae pierce the skin and shed their tails
  • Enter blood vessels and migrate to the hepatic portal blood vessels
  • Develop in the liver and they migrate target sites
  • Eggs released by females are extruded through gut or bladder lining and exit with feces or urine
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23
Q

Eggs that remain behind become centers of inflammation in Schistosoma

A

Trues

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24
Q

Phylum Platyhelminthes
that parasitizes humans, pigs, rodents, etc.
Eggs are coughed up in sputum, then swallowed and eliminated in feces
Human infection occurs by eating uncooked crabmeat

A

Paragonimus westermani: Lung Flukes

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25
Q

Metacercariae of Paragonimus westermani: Lung Flukes develop in

A

freshwater crabs

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26
Q

Cercariae of Paragonimus westermani: Lung Flukes shed into the water and ingested by

A

freshwater crabs

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27
Q

Paragonimus westermani: Lung Flukes Life Cycle

A

*Eggs are coughed up in sputum, then swallowed and eliminated in feces
*Zygotes develop in water and miracidia penetrate a snail host
*Within the snail, miracidia give rise to sporocysts, which develop into rediae
* Cercariae are shed into the water and ingested by freshwater crabs
* Metacercariae develop in freshwater crabs
*Human infection occurs by eating uncooked crabmeat

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28
Q

Monogenetic flukes
were originally placed in Trematoda
External parasites of fish especially gills, but a few are found in bladders of frogs and turtles
Have direct life cycle in a single host

A

Class Monogenea

29
Q
  • Some now argue they are sister taxa, Trematoda and Monogenea having a posterior attachment with hooks
A

true

30
Q

Class Monogenea
part that attaches to host by posterior hooks

A

Oncomiracidium

31
Q

Class Monogenea

Posterior hooks may become the posterior attachment organ of the adult, the

vary widely (hooks, suckers, clamps)

Withstand the force of water flow

Some serious economic problems in fish farming

A

opisthaptor

32
Q

have long flat bodies with scolex
Lack a digestive system
Muscles, excretory and nervous systems similar to other flatworms
Lack sensory organs except for modified cilia

A

Class Cestoda
Tapeworms

33
Q

Class Cestoda
Holdfast structure with suckers and hooks

A

scolex

34
Q

Class Cestoda
Scolex is followed by a linear series of reproductive units or

A

proglottids

35
Q

Class Cestoda
the long body of the Tapeworms

A

strobila

36
Q

Class Cestoda
* Lives as an adult in the alimentary canal of humans
* exists in beef
* Mature adults can reach over 10 meters in length with over 2000 proglottids
* Scolex has four suckers but no hooks
Gravid proglottids pass in feces
*no suckers

A

Taenia saginata: Beef Tapeworm

37
Q

Taenia saginata: Beef Tapeworm
*Juvenile form found in

A

intermuscular tissue of cattle

38
Q

each segment in the strobila of a tapeworm, containing a complete sexually mature reproductive system.

A

proglottids

39
Q

segment that contains uterine branches filled with eggs, or shelled infective larvae

A

Gravid proglottids

40
Q

Taenia saginata Life Cycle

A
  • Cattle swallow shelled larvae that hatch as oncospheres
    *Oncospheres use hooks to burrow through the intestinal wall into blood or lymph vessels
  • When they reach voluntary muscle, they encyst to become bladder worms (cysticerci)
  • When the infected meat is eaten, the cyst wall dissolves and the scolex evaginates to attach to intestinal mucosa
    *New proglottids develop in 2–3 weeks
    *Infected individuals expel numerous proglottids daily
    *Infection can be avoided by eating only thoroughly cooked beef
41
Q

Phylum Platyhelminthes
* Adults live in small intestine of humans
* found in pork
* Scolex has both suckers and hooks on the
rostellum

A

Taenia solium: Pork Tapeworm

42
Q

Phylum Platyhelminthes
*Juveniles live in muscles of pigs

A

Taenia solium: Pork Tapeworm

43
Q

If eggs or proglottids of Taenia solium: Pork Tapeworm are ingested
what happens

A

⚬ Embryos migrate to organs and form cysticerci

44
Q

commonly occurs in eyes or the brain blindness, serious neurological symptoms or death, caused by Taenia solium: Pork Tapeworm

Infection can be avoided by eating thoroughly cooked pork

A

Cysticercosis

45
Q

Phylum Platyhelminthes

Adults found in intestines of humans, dogs, cats and other mammals
Immature stages found in crustaceans and fish
Largest cestode of humans, reaching up to 20 meters in length

A

Diphyllobothrium latum: Fish Tapeworm

46
Q

Phylum Platyhelminthes

  • Adults parasitize dogs and other canines
    *Juveniles infest many mammals
    *Humans may serve as intermediate host
  • Main cyst maintains a single chamber
    ⚬ Daughter cysts bud off with thousands of
    scolices, each able to produce a worm if
    eaten
  • Surgical removal is the only treatment
A

Echinococcus granulosus: Unilocular Hydatid

47
Q

Echinococcus granulosus: Unilocular Hydatid Juveniles are a special cysticercus, a hydatidcyst, that grows for up to

A

20 years

48
Q

Neodermatans are composed of

A

trematodes, monogeneans, and cestodes

49
Q

taxon Turbellaria is paraphyletic

A

true

50
Q

Neodermatans form a monophyletic group

A

true

51
Q

Allied with trematodes, monogeneans, and cestodes as the sister group to endolecithal turbellarians

A

Ectolecithal turbellarians

52
Q

phylum
Considered a “missing link” between protozoa and metazoa
Have a simple level of organization
Minute, ciliated, and wormlike animals

A

Phylum Mesozoa

53
Q

Phylum Mesozoa All live as parasites in

A

marine invertebrate

54
Q

Phylum Mesozoa
Most composed of only ________ cells arranged in two layers
Layers are not homologous to germ layers of other metazoans

A

20 to 30

55
Q

Phylum Mesozoa
Two classes

A

Rhombozoa and Orthonectida

56
Q

Phylum Mesozoa
* Live in kidneys of benthic cephalopods
*Inner, reproductive cells give rise to vermiform larvae
* When overpopulated,reproductive cells develop into gonad-like structures producing male and female gametes
* Larvae are shed with host urine into the seawater

A

Rhombozoans

57
Q

Rhombozoans
Adults called ________ and are long and slender

A

vermiforms

58
Q

Phylum Mesozoa
* Parasitize variety of invertebrates
* Reproduce sexually and asexually
* plasmodium

A

Orthonectids

59
Q

Orthonectids
Asexual reproduction consists of a multinucleated mass called a

A

plasmodium

60
Q

Some consider these organisms primitive flatworms and place them in phylum Platyhelminthes

A
61
Q

Molecular evidence groups Phylum Mesozoa with flatworms in

A

superphylum Lophotrochozoa

62
Q

orthonectid and two species from a rhombozoan subgroup, the dicyemids, did not show members of the two classes to be

A

sister taxa

63
Q

Phylum Mesozoa may not be monophyletic

A

true

64
Q

*Often called ribbon worms
*Have a long muscular tube, the proboscis
*Over 1000 species
* Most are less than 20 cm long
*General body plan similar to that of turbellarians
* Epidermis is ciliated with many gland cells
* Excretory system has flames cells; several have rhabdites
* Mostly dioecious

A

Phylum Nemertea

65
Q

long muscular tube in Phylum Nemertea

A

proboscis

66
Q

Phylum Nemertea
wjay is the shape of their pilidium larva

A

Helmet-shaped pilidium larva

67
Q
  • Adult has an anus, producing a complete digestive system that is more efficient
  • Simplest animals with a blood-vascular system
  • Most are marine
    ⚬ Some are found in moist soil and freshwater
  • Few are commensals or parasites
A

Phylum Nemertea

68
Q

Ventral mouth but no anus resembling flatworms and trochophore larvae of annelids and molluscs

A

pilidium larva

69
Q

regenerate readily
* Some fragment themselves during certain seasons
* Tail sections can regenerate a new proboscis within a short time

A

Phylum Nemertea

70
Q

Phylum Nemertea Classes

A

Class Enopla
Class Anopla

71
Q

Phylogeny of Nemertea

A
  • Much debate about the phylogenetic position of nemerteans
  • Larval forms vary
    *Nemertean body plan is controversial
  • Are they coelomate or acoelomate?

SYSTEMATICS (12 decks)

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