Phylum
Platyhelminthes
The following questions
will
help you to review the material from the lecture, lab as well as the
text.
- Briefly characterize the
phylum
Platyhelminthes.
- Flatworms are
acoelomates. Explain!
- One of the
characteristics of
the taxon is the flat dorsally-ventrally flattened shape of the
organisms.
What kind of physiological advantages are associated with such a
shape?
- Bilateral symmetry
favored the
evolution of two major aspects of animals. What are these
characteristics?
Why did bilateral symmetry favor their evolution?
- How many species are
represented
by the taxon? How many of those are free-living? Parasitic?
- Briefly describe the
taxonomy
of the taxon (classes). Which of these classes are parasitic?
- Briefly describe the
class Turbellaria.
- The planarians are often
used
to describe the structural and functional anatomy of the group.
Describe
the basic anatomy of a planarian (use Dugesia
as example)..
- What is the basic
structure and
function of the tegument? Does the tegument differ between
free-living
and parasitic species?
- How do planarians move?
- Are muscles present? If
so, how
are they arranged in a planarian? Are they only used for movement?
- Describe the feeding
behavior
of a typical planarian. How does a planarian feed, digest and absorb
their
food?
- Polyclad flatworms are
often brightly
colored due to a variety of pigments. Why?
- Many nudibranchs
resemble polyclad
flatworms (or is it the other way around?). Explain the reason for
the
similarities.
- Flatworms have an
enormous innate
ability to regenerate. Briefly describe this aspect of the phylum
with
the help of the regeneration experiments described in lecture.
- What are flame cells?
Importance?
- Briefly outline the
nervous system
of a planarian. How does this system differ from the members of
phylum
Cnidaria?
- What kind of sensory
input do
free-living flatworms typically respond to?
- What are the eye spots
on a planarian.
What kind of visual information do they respond to?
- How do planarians
reproduce?
- How do flatworms solve
the problems
of gas exchange? Excretion of waste?
- Briefly describe the
class Monogenea.
- Briefly describe the
class Trematoda.
- What are flukes? What is
their
biological importance?
- How do flukes gain
access to nutrients?
- Describe the species Schistosoma
mansoni as a representative of the class Trematoda.
- Briefly describe the
pathology
and importance of the disease schistosomiasis. Where does the
disease
occur?
- Describe the life cycle
of Schistosoma
mansoni. [Make sure to know and
understand
this
life cycle]
- What are miracidia? What
are cercariae?
- Why is the intermediate
host so
important to consider as one tries to reduce the incidence of the
disease?
- Under what kind of
conditions
are humans most likely to be exposed to the disease?
- Briefly describe the
class Cestoidea/Cestoda.
- What is a scolex? What
is a proglottid?
[function and structure]
- How do these worms
reproduce?
- Outline the main
physiological
characteristics of the phylum Platyhelminthes.
