Download Chapter 30: Comparing Invertebrates

Chapter 30: Comparing Invertebrates
Section 1: Evolution of the Invertebrates
Evolution of the Invertebrates

The evolutionary relationships between different groups of organisms can be
shown in the form of a diagram called a _________________________________
o Shows our best understanding of which phyla originate from a
______________________________________ and approximately when
evolutionary lines _______________________

The __________________________________ represents the common ancestor of
all the groups shown on the tree

Branches that originate close to the _____________________________________
represent groups that _______________________________________

Branches that originate near the ________________________________________
represent groups that ________________________________________________
_____________________________

The tips of the branches represent _____________________________________

Some phylogenetic trees show “dead” branches that do not reach the outside of
the tree

Dead branches represent _________________________ evolutionary lines

There are no living groups from these lines

There are several _____________________________________ on a phylogenetic
tree

Figure 30 – 3
o ____________________________, ______________________________,
____________________________, ______________________________,
and ______________________________

These branches represent basic evolutionary lines in animals with
____________________________________

The division of animals into deuterostomes and protostomes is based on events in
_____________________________________________

The division of animals into acoelomates, pseudocoelomates, and coelomates is
based on the _______________________________________________________
Early Development

____________________________ include flatworms, roundworms, annelids,
mollusks, arthropods, and the members of most of the minor
____________________________________________

______________________________________ include echinoderms, several
small phyla of strange-looking marine animals we have not discussed, and all
members of our own phylum, Chordata

To understand the reasons for dividing animals into protostomes and
deuterostomes, we must examine the earliest stages in the development of animals

Soon after an egg has been fertilized, it begins a series of
_________________________

These divisions lead first to a _______________________________ and then to a
_________________________________

When the embryo grows from ________________________________________,
the new cells can be arranged in different ways

In ________________________________, which occurs in almost all
__________________________________, the four new cells sit _____________
________________________ the four older cells

In _____________________________________, which occurs in almost all
_________________________________, the four new cells sit ______________
___________________________ the four older cells

In both protostomes and deuterostomes, the cells of the embryo continue to divide
until they form a ______________________________

Then the ball becomes _____________________________________________
and folds in on itself

The layer of cells on the outside of the ball is called the
_______________________

The layer of cells that has folded inside the ball is called the
_______________________

Both the endoderm and ectoderm eventually develop into
____________________________________________________________

The round central cavity enclosed by the endoderm will become the
_________________________________________ of the developing embryo

The opening of this cavity to the outside is called the _______________________

It is the blastopore that determines whether an animal is a protostome or a
deuterostome
o If the blastopore becomes the ____________________, the animal is a
____________________________
o If the blastopore becomes the __________________ and an opening that
appears later becomes the mouth, the animal is a
______________________________

There is a third cell layer in embryos, called the __________________________,
which is located between the endoderm and the ectoderm

Many important tissues, ________________________________________,
develop from the mesoderm
Body Cavities

Body cavities are important for several reasons
o Provide a space in which ______________________________________
can be suspended so that they are not pressed on by muscles and twisted
out of shape by body movements
o Allow room for internal organs to ________________________________
o _____________________________________ that may be involved with
internal transport, or the carrying of food, wastes, and other materials from
one part of the body to another

Some phyla, such as flatworms, have no body cavity at all
o __________________________________

Other phyla, such as roundworms, have a body cavity that is partially lined with
mesoderm
o __________________________________

Still other phyla have a true _________________________, or body cavity that is
completely lined with mesoderm
o ________________________________

More advanced than the other two

The complete mesoderm lining makes it possible for the digestive
tract to develop specialized regions and organs, allows for the
formation of blood vessels, and makes it easier for complex organ
systems to develop