Platyhelminths Flashcards
Platyhelminthes came from what Greek words
platy + helminth = flatworms
Group of worms that are dorsoventrally flattened
Platyhelminths
True or False
Platyhelminths has no uniquely defining characters (synapomorphies).
True
True or False
about 70% of Platyhelminths are parasitic
False
80% are parasitic
- Trematodes
- Cestodes
- Monogeneans
Free-living representatives
Most primitive, basal species among bilateral animals
Group Turbellaria
First group of bilateral animals to have evolved a true mesoderm
Platyhelminths
Triploblastic
Parasitic multicellular animals that were once regarded as possible flatworm relatives because their body plan resemble that of turbellarians
Mesozoans
Mesozoans came from what Greek words
meso + zoon = “middle animals”
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
tiny acoelomate animals with numerous spines in their body
gastrotrichs
considered to be true metazoans or acoelomate eumetazoans
Platyhelminths
True or False
About 34,000 described species of Platyhelminths
True
They exhibit a solid grade of construction–acoelomates.
Wherein a special parenchymatous connective tissue (derived from mesoderm) separates the organ systems
Platyhelminths
What is the parenchymatous connective tissue for
parenchymatous connective tissue enables the animal to regenerate
True or False
Are Platyhelminths bilaterally symmetrical with cephalization
True
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)
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)
True or False
Platyhelminths are nearly always hermaphroditic
True
True or False
cross-fertilization is uncommon in Platyhelminths
False
It is very common
What is unique to Platyhelminths
Division of the ovary into a germarium, and vitellarium
What produces the eggs
germarium
What produces the nutritive and shell-forming cells
vitellarium
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
True or False
Platyhelminths have circulatory or respiratory system
False
No circulatory or respiratory systems (diffusion is possible across the thin body)
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
