Flashcards in Flatworms Deck (62):
Two major evolutionary advances of flatworms
Primary bilateral symmetry
triploblastic and either acoelomate or pseudocoelomate
Body flattened dorsoventrally
Acoelomate (atypical !)
Have a cellular ciliated epidermis
Which systems do Phylum Acoelomorpha not have?
NO excretory or respiratory system. Lack protonephridia
What does the digestive system of Phylum Acoelomorpha have
mouth → tube-like pharynx→sack-like gut (incomplete)
In many acoels what are absent and has no
the gut and pharynx are absent
What type of digestion does Acoelomorpha have
Acoelomorphs lack a
true brain, Lack ganglion (mass of nerve cell bodies).
Diffuse system of anterior neurons connected to
radially arranged nerve cords,
What is :
crown of ciliated tentancles.
Efficient feeding device
Used for respiration
What does the Trochophore larva do?
free swimming, feeding, with ring of large cilated cells in front of mouth (prototroch).
Prototroch used in swimming and feeding.
In Lophotrochozoan Protostomes members (should) have in common either a
Lophophore or Trochophore larva.
Platyhelminthes lack a single unique character so they are NOT
Class Tubellaria are
In the Phylum Platyhelminthes which three classes are parasitic?
Trematoda, Monogenean and Cestoda
A. Ciliated ventral surface
B. Subtle muscular contraction
C. Dual-gland adhesive organs
Locomotion of Turbellaria
Locomotion of Turbellaria has what three parts?
1. Paired viscid cells (glands)
- produce adhesive secretions that
attach anchor cells to substratum
2. Anchor cells
- bear strain of attachment & allow
subtle muscular contractions to pull the animal forward
muscular contraction = pedal wave
3. Releasing cell (gland)
- secretes chemicals that release anchor cell attachment
what is a Protonephridium
an 'inverted' flagellated cell (flame cell) sitting in a 'mesh cup' (tubule end)
In osmoregulation the fluid is "ultra filtered" and modified and eliminated through what
- Less important role as an excretory system (metabolic waste removal).
The nervous system has degrees of organization from a nerve plexus- how many nerve cords
nerve cords (1 – 3 pairs), with connecting nerves (ring commissures) forming a “ladder-type” pattern
What are the four parts of the nervous system?
Auricle, cerebral ganglion, nerve cord and ring commissures
Ocelli does what
Senses water flow
Statocyst are used for what
What are four characteristics of the class Turbellaria
Mostly free-living forms
Most are bottom dwellers in marine or freshwater
Terrestrial flatworms limited to moist places
Carnivorous and detect food by
-Food trapped in mucous secretions from glands and rhabdites
-Wrap themselves around prey
Extend the proboscis to suck up bits of food
Extracellular digestion completed by intracellular digestion.
What are the three main classes of parasitic Platyhelminths.
Most adults in Trematoda are
endoparasites of vertebrates
What are four adaptations for parasitism in Trematoda
-Glands to produce cyst material
-Hooks and suckers for adhesion
-Increased reproductive capacity
Which class has:
Most species dorsoventrally flattened
Usually leaf shaped
Covered by a syncytial tegument
Class Trematode Characteristics
Traditionally placed in the Class Trematoda but now forms its own class
simple life cycle.
Monogenean (fish flukes)
What is also known as mammal flukes
The digestive system in Digenean adults is
either absent or rudimentary
The excretory system in Digenea adults contains
ciliated cells (flame cells= protonephridia) extending into excretory tubules.
Most species are hermaphroditic for what
How many stages are there in Digenean life cycle: Parasitic strategies
The Digenea Life cycle has ___ developmental stages
Digenea Life cycle has __ or more hosts. And which one is high and low
2. first one is high, the second is low
Digenea Life cycle: adulthood is reached only in
definitive* vertebrate host
definitive host is where sexual reproduction occurs
Adults- usually parasites of vertebrate animals
Larvae-may be free-living or infect vertebrates or invertebrates.
parasitic forms- enter their hosts via the digestive system or by penetration of the skin.
Schistosome (blood flukes) are found in? and are agents of ____?
they have separate sexes
Found in veins, intestine and urinary bladder
Causative agents of schistosomiasis
What is the Infective stage called in schistosomiasis
What is swimmer’s itch?
Schistosome dermatitis -
when cercariae penetrate an unsuitable host (i.e. a human)
In Monogena most fish are
some - found in urinary bladder, lower intestine of frogs and turtles.
in nature they cause little economic damage but can be very destructive in fish farming.
Monogena life cycle goes through: Direct development.
“Monogenea” = 1 generation. 1 egg = 1 adult
No intermediate hosts → Autoinfection - possible for some species.
ciliated larvae, has eyespots, a rudimentary digestive system and an opisthaptor to attach to its new host.
Why is the Opisthaptor important?
because they are typically ectoparasites and need to hang onto hosts.
What are the two hosts of Cestoda Tapeworms
definitive host - a vertebrate, (sexual reproduction)
intermediate hosts – either a vertebrate or an invertebrates.
What is the morphology of the Class Cestoda Tapeworms
quite different in appearance from the other members of the Platyhelminthes.
dorso-ventrally flattened, tape-like bodies.
Lack a head and gut.
What is is the general structure of an adult Class Cestoda Tapeworms
NB Not “true” segmentation
attachment to their host
contains suckers and hooks
Remnant of posterior part of body.
zone of proliferation
- undifferentiated area behind the scolex
a chain of many reproductive units (proglottids )
immature proglottids - developing reproductive
mature proglottids: mature reproductive organs.
gravid proglottids: contain eggs in the uterus.
-Cestodes, like trematodes and monogeneans, have no external motile cilia.
-entire surface of cestodes is covered with small projections called microtriches similar to microvilli seen in the vertebrate small intestine.
Larval Cestodes (Metacestodes) what is important to know
Most pathogenic stage
Result in economic loss
What is a causative agent of Taeniasis in dogs, cats and humans, and cysticercosis in the mammalian intermediate host (IH)
What is the infective stage of the intestine of definitive host (DI) - adults
What is the infective stage of In various tissues of IH (usually forms cysts) -
egg with oncosphere