Platyhelminths Flashcards by Shaira Ann Rueco

Platyhelminthes came from what Greek words

platy + helminth = flatworms

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Group of worms that are dorsoventrally flattened

Platyhelminths

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True or False

Platyhelminths has no uniquely defining characters (synapomorphies).

True

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True or False

about 70% of Platyhelminths are parasitic

False

80% are parasitic

Trematodes
Cestodes
Monogeneans

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Free-living representatives

Most primitive, basal species among bilateral animals

Group Turbellaria

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First group of bilateral animals to have evolved a true mesoderm

Platyhelminths

Triploblastic

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Parasitic multicellular animals that were once regarded as possible flatworm relatives because their body plan resemble that of turbellarians

Mesozoans

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Mesozoans came from what Greek words

meso + zoon = “middle animals”

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True or False

Phylogenomic analyses propose that dicyemids and orthonectids are more related with with mollusks and annelids than they are with gastrotrichs and platyhelminths than

False

Phylogenomic analyses propose that dicyemids and orthonectids are more related with gastrotrichs and platyhelminths than they are with mollusks and annelids

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tiny acoelomate animals with numerous spines in their body

gastrotrichs

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considered to be true metazoans or acoelomate eumetazoans

Platyhelminths

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True or False

About 34,000 described species of Platyhelminths

True

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They exhibit a solid grade of construction–acoelomates.

Wherein a special parenchymatous connective tissue (derived from mesoderm) separates the organ systems

Platyhelminths

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What is the parenchymatous connective tissue for

parenchymatous connective tissue enables the animal to regenerate

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True or False

Are Platyhelminths bilaterally symmetrical with cephalization

True

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True or False

A system of flame cells and excretory vessels are nearly always present in Platyhelminths

True

Protonephridial excretory system for osmoregulation (a primitive type of excretory system)

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True or False

Platyhelminths have complete digestive system

False

The gut, when present, may be well developed or may just consist of loose syncytium (multinucleated cell)

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True or False

Platyhelminths are nearly always hermaphroditic

True

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True or False

cross-fertilization is uncommon in Platyhelminths

False

It is very common

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What is unique to Platyhelminths

Division of the ovary into a germarium, and vitellarium

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What produces the eggs

germarium

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What produces the nutritive and shell-forming cells

vitellarium

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The nervous system of Platyhelminths is ladder type.

Is ladder type more advanced than nerve net?

Yes. Ladder type is more advanced than the nerve net nervous system of cnidarians

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True or False

Platyhelminths have circulatory or respiratory system

False

No circulatory or respiratory systems (diffusion is possible across the thin body)

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What are considered important for taxonomic identification of Platyhelminths

Anatomical features of the reproductive organs Eggs and larvae are also distinct among different species

What are protostomian characteristics

Undergoes spiral cleavage, determinate, and mouth was formed from blastopore

Where are free-living representatives found

Water or damp places on land

What class are mostly free-living, and many of which are predators or scavengers

Class Turbellaria

What is the unique feature of Class Turbellaria

Epidermis that is partially ciliated and usually with inclusions known as rhabdites

What are mucus secreting cells that function for protection, movement, capturing of prey, and swallowing

Rhabdites

Is gut cavity present in Class Turbellaria?

Yes, except in Order Acoela

Does Class Turbellaria reproduce sexually?`

Yes, - Sexual reproduction is through copulation

perm is introduced by a copulatory organ called

cirrus

True or False Class Turbellaria's life cycle is simple

True usually direct with juvenile worm that resembles the adult emerging from an egg but occasionally free-swimming larvae (e.g. polyclad Goette’s and Muller’s larva) are present.

What were once used to classify the turbellarians into two subclasses

Anatomy of reproductive organs, egg type, and digestive tract

What are the two subclasses of Class Turbellaria?

Archoophora (primitive egg bearers) and Neoophora (new egg bearers)

What made archoophora to be not considered as a subclass

archoophora was found out to be paraphyletic taxon

True or False Majority of turbellarians, as is the case for the entire group of platyhelminths, have questionable apomorphies hence are better treated without the Linnaean superscript

True

Without separate yolk glands; entolecithal eggs; exclusively marine

ARCHOOPHORA

Order under archoophora that has a gut without pharynx and devoid of a cavity; and the gut instead consists of a loose digestive

Order Acoela

Order under archoophora that has gut with pharynx and numerous intestinal caeca, which are branched and radially

Order Polycladida

Ovary divided; ectolecithal eggs; marine, freshwater, and terrestrial species present.

NEOOPHORA

Order under neoophora that has gut with pharynx and usually a simple undivided intestine

Order Rhabdocoela

Order under the neoophora that lives in outer surfaces of some freshwater animals which they have a specific relationship with; Pharynx leads to a sac-like intestine;

Order Temnocephala some refer to these Temnocephalids as ectoparasites.

peculiar external features of Order Temnocephala include

a posterior sucker and anterior tentacles (exhibit leech-like locomotion)

The intestine with 3 main limbs: 1 anterior and median, and 2 posterior and lateral, each having many diverticula.

Order Tricladida

The mouth of Order Tricladida is found on the mid-ventral surface and leads to the pharynx. Do they have a plicate pharynx?

Yes, Triclads have a plicate pharynx, which can be protruded to suck in food and folded when it is withdrawn. This includes the common planaria (Dugesia sp.)

Trematoda came from the Greek word

trema” which means “a hole.” This refers to the cavity of the holdfast organs of trematodes.

True or False All members of Trematoda are endoparasites

True

What are the characteristics of the class Trematoda?

Ventral and oral adhesive organs mouth is typically located at the anterior end Body covered with a non-ciliated cytoplasmic syncytium (tegument)

True or False Trematoda only have a simple life cycle

False Life cycle may be simple or complex.

What subclass have larval stages that give birth to other larvae making its life cycle complex that involve several hosts?

SUBCLASS DIGENEA Greek words di + gena meaning “two births” This type of reproduction ensures the large volume of larvae production to increase the chance of successfully gaining access to their intermediate and definitive hosts

Generally known as digenean fluke and consists 99% of all trematodes

SUBCLASS DIGENEA

Is Subclass Digenea an economically and medically important taxon?

Yes, parasitizing important animals such as fish, amphibian, reptile, bird, and mammals including human

A vertebrate parasitized by an adult digenean is called

primary or definitive host

A mollusk or annelid harboring the asexually reproducing digenean is called

first intermediate host

True or False? crustaceans or small fishes are secon immediate host

True

True or False Gut of Digenean is not always present and does not have an oral sucker surrounding the mouth

False Gut always present and provided typically with an oral sucker surrounding the mouth, to aid in feeding and a ventral sucker or acetabulum (attachment organ to prevent dislodgement), pharynx, and bifurcated intestines (blind-ended)

True or False SUBCLASS ASPIDOGASTREA is a small group containing about 60 species

False Small group containing about 80 species

What subclass bear resemblance with monogenea and digenea, but no haptor and no asexual reproduction in the life cycle

SUBCLASS ASPIDOGASTREA require an intermediate host (mollusc)

True or False Class Cestoda are all endoparasitic

True Include the very familiar tapeworms

True or False Gut of Cestoda is complete

False Gut completely absent, the nutrient being absorbed through the surface of the body

Adult Cestoda have nonciliated epidermis called

tegument

What is present on the tegument that increases absorptive area for this parasite that lacks digestive tract.

microvilli (microthrices)

Attchement organs of Class Cestoda are in the form of

suckers sucking muscular grooves or folds (bothria), semicircular or leaf-like bothridium sometimes armed with tentacles, or hooks (rostellum) nearly always present at the scolex (head) and are important features for identifying species.

sucking muscular grooves or folds

Bothria

Hooks that are nearly present at the scolex (head)

Rostellum important features for identifying species.

The body region behind the scolex is called

neck which is a zone of active cell proliferation that will give rise to proglottids resulting to pseudometameric strobila.

True or False Immature proglottids develop into mature stage as male and female organs develop.

True

True or False In Class Cestoda, Self and cross-fertilization may occur.

True

Fertilization may happen where?

within proglottid, between proglottids, or cross-fertilize between two worms.

Each gravid proglottid may contain how many eggs?

50,000 eggs.

True or False Pseudometamerism corresponds to metameric segments of the other phyla.

False Pseudometamerism does not correspond to metameric segments of the other phyla.

What is the process where older segments are moved further from the scolex.

strobilization (~strobilation or proglottidization

True or False In true metamerism, new segments (except for the first segment bearing the anus) are produced distally from the head region.

True

Where do Cestodes who do not strobilate belong

Subclass Cestodaria

Majority strobilate and they belong to

Subclass Eucestoda or the true cestodes.

True or False The life cycle of Cestoda is simple

False Life cycle is complex (requiring more than one host)

gravid proglottids are detached singly or in chains and the eggs are set free by disintegration of the gravid proglottids

Apolysis

chains of exhausted proglottids are detached after egg production has ceased

Pseudoapolysis

there are provisions for the release of eggs such as the uterine pore.

Anapolysis

True or False Class Monogenea is typically ectoparasites

True

True or False Life cycle of Class Monogenea is complex that requires two or more intermediate hosts

False Life cycle simple (no asexual multiplication) and does not require an intermediate host.

True or False Monogeneans are host-specific and confined only to a unique site on the host.

True

What is a free-swimming larva, bearing 3 bands of cilia and usually 1 or 2 pairs of eyes called

oncomiracidium

The most prominent morphological feature of monogeneans is ...

posterior attachment organ called opisthaptor G: opistho= behind or at the rear; hapto = fastened)

The anterior sucker of monogeneans consisting of suckers and adhesive glands to aid in attachment to its host is called

prohaptor

Platyhelminths Flashcards

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