Phylum
Mollusca
The following questions will
help you to review the material from the lecture, lab as well as the
text.
- How does the phylum
Mollusca correspond in size (number of species) with the other
animal phyla we are studying this semester? How many species are
found within the phylum?
- What kind of animals are
found within the phylum Mollusca? Examples of animals?
- In what kind of
environments do these animals live?
- What are some "new" major
evolutionary features present in this phylum?
- What are the four major
body features that these animals have in common? Use the concept of
the "ancestral mollusk" [HAM]
to outline the body plan (bauplan) that these animals have.
Draw a diagram of the "ancestral" mollusc and label all the major
parts of its body.
- What is the foot? The
visceral mass? The mantle? The head?
- What is a radula? What is
it used for? Does the structure of the radula vary within the
phylum? Why or why not?
- Many molluscs have a
shell. What is the shell made of? How is the shell produced? Why do
not all molluscs have a shell (or do they)?
- What is the function of
the shell?
- Explain the evolutionary
pressure/s that led to the evolution of the shell. The ancestors of
the molluscs where soft bodied animals without a shell. What events
occurred that triggered this major shift?
- What are the advantages
and disadvantages with having a shell?
- When did the phylum
Mollusca originate in the fossil record? Is this phylum well
represented in the fossil record?
- Give a brief overview of
the diversity within the phylum Mollusca. What are the names of the
four major classes? Which of the four classes is most "ancient"? How
do we know?
- Explain the concept of
adaptive radiation. How is this concept exemplified
by the phylum Mollusca? Explain.
- Characterize the class
Polyplacophora. Where does one find these animals? How are they
adapted to that specific environment?
- What do chitons feed on?
How do they feed?
- Make a brief sketch of
the body of a chiton.
- The class Gastropoda is
the largest within the phylum Mollusca. How many species does this
class represent? Give a brief overview of the diversity of species
within this class.
- Explain the phenomenon
referred to as torsion. What are the implications of torsion on the
anatomy of a Gastropod? What is the evolutionary explanation of
torsion?
- Is the torsion of a shell
and the torsion of the body linked in any way?
- What is the importance of
Gastropods for humans?
- Make a diagram of the
anatomy of a typical Gastropod (e.g. a garden snail) and label the
major parts of the body.
- What is an operculum? A
pneumostome?
- How do gastropods move?
- Gastropods feed on a
variety of diets depending on the species. Give a few examples of
their diet.
- What is a suspension
feeder? How do they gather food?
- Briefly explain the
concept of open circulation. How does it work? What is the
difference between open and closed circulation? In which classes
within the phylum do you find these systems?
- Would you consider that
the nervous system in these animals as a complex one? How does it
differ between the different classes? How do these animals sense the
world?
- What is the difference
between a dioecious and a monoecious species?
- What is a trochophore
larvae? A veliger larvae?
- Are the nudibranchs
typical gastropods? Explain. Many of them are very colorful. Why is
that?
- Characterize the class
Bivalvia. How does this class differ from the class Gastropoda? Draw
a figure of the anatomy of a typical bivalve and label major body
parts.
- How do bivalves feed?
Move? Reproduce?
- Characterize the class
Cephalopoda. Give a few examples of animals found in this taxon.
- Compare the class
Cephalopoda with the three others you are studying. How do they
differ from each other. How are they similar?
- What kind of
modifications have occurred in the body plan of a Cephalopod (e.g.
with the foot as well as the mantle)?
- Try to explain why this
change occurred from an evolutionary perspective.
- Do shells occur within
the class Cephalopoda? Explain.
- Describe the body
structure of the Nautilus. How is this body connected to the origins
of this class of animals?
- Where do you find the
Nautilus? How does this animal capture food? How does it control
buoyancy?
- How do cephalopods change
their colors? Give several reasons for why this feature has become
so advanced within the class. What is the ability used for?
- Why is the nervous system
of Cephalopods so much more advanced compared to the other three
classes?
- Briefly discuss the the
evolution of vision within this class as compared to other animals.
- Describe the life cycle
of squid.
- Make a diagram of the
anatomy of a squid and label major structures as well as their
function.
- Summarize the
characteristics of the phylum Mollusca! Make sure to emphasize any
new features present within the taxon.
Links:
Recommended Reading:
[Note: Angel disables links to Amazon
URLs
- these are great introductions to aspects of Mollusca]
