Transcript Survey of the Phyla-Animaia InverION

Survey of the PhylaAnimalia,
Invertebrates
The Kingdom Animalia is in
the domain Eukarya and in
the supergroup Unikonta.
They are in the group
Opisthkonta with fungi.
Both groups have different
unicellular organisms that
are their common ancestor.
That fact indicates the
groups became
multicellular organisms
independent of one another.
Characteristics of the Animal Kingdom
1. Animals are multicellular, heterotrophic, ingestive and eukaryotic.
2. The cells lack cell walls and are held together by structural
proteins which are mostly collagen. They have intracellular
junctions such as tight junctions, desmosomes and gap junctions.
3. Animal cells have nervous and muscle tissues found only in this
kingdom.
4. Most animals have a diploid life cycle with a sperm fertilizing an
egg. The zygote undergoes cleavage forming a blastula (hollow ball
of cells). The blastula undergoes mass movement of cells to form a
gastrula giving rise to three layers of tissue, endoderm, mesoderm
and ectoderm. Often there is a larval stage to the animal which is
sexually immature. It often will undergo metamorphisis to become
an adult.
5. All animals contain both
homeotic genes (any of the genes
that control the overall body plan
of animal by controlling the
developmental fate of a group of
cells) and homeobox (a 180nucleotide sequence with a
homeotic gene) encoding the part
of the protein that binds to the
DNA of the genes regulated by the
protein. There is an increase in the
number of these genes with an
increase in the complexity of the
animal.
The protists most closely related to
animals are the choanoflagellates.
It is flagellated with a collar to
collect food. It will form colonies.
Other interesting points about animals
Embryonic development
-Deuterostomes versus protostomes. During development many
animals first form a hollow ball of cells or blastula. Afterward
that there is a mass movement of the cells called gastrulation.
This process results in three layers of tissue being established.
Ectoderm-becomes skin and nervous tissue
Mesoderm-notochord, lining of coelom, kidneys, muscles and
bone and circulatory system
Endoderm-interior lining of organs and liver, pancreas, lungs
and lining of digestive tract.
During this process of gastrulation, the first opening to the gut
or archenteron forms. In deuterostomes, this opening becomes
the anus but in protostomes it becomes the mouth.
1. Among the characteristics unique to
animals is
A) gastrulation.
B) multicellularity.
C) sexual reproduction.
D) flagellated sperm.
E) heterotrophic nutrition.
1. ANS: A
The process of gastrulation occurs in
animal development (not all animals). It is
the mass movement of cells from the
hollow ball of cells to establish three
embryonic tissue layers, ectoderm,
endoderm, and mesoderm.
Other organisms such as plants and fungi
are multicellular. Many organisms
including most protists have sexual
reproduction with the production of
flagellated sperm cells. Fungi, certain
Body plansAsymmetrical-These animals lack orientation like the sponges.
Radial symmetry-The body plan is around an axis and any
plane going through the axis will produce opposite halves.
-Bilaterial symmetry
The body forms a
body in a
longitudinal plane
that divides the body
into two equal but
opposite halves. It
allows the senses to
be concentrated in
one area (the
“head”). Can
increase awareness,
mobility and
predation.
Bilateral symmetry in the animal kingdom
is best correlated with
A) an ability to sense equally in all
directions. B) the presence of a
skeleton.
C) motility and active predation and
escape. D) development of a true
coelom. E) adaptation to terrestrial
environments.
ANS: C
Bilateral symmetry is associated with an
increase in motility, predation and escape.
-Bilateral symmetry (animals with this are known as bilateria)
The body forms a body in a longitudinal plane that divides
the body into two equal but opposite halves.
Body cavities (coeloms)
-Acoelomate-These animals do not have a body cavity like a
flat worm or jelly fish
-True coelom-The body cavity is lined with tissue derived
from the mesoderm and therefore the cavity is surrounded
completely by mesoderm.
-Pseudocoelom-The body cavity is lined with mesoderm on
the outer part and with endoderm on the inside. Round
worms have pseudocoeloms.
3. Acoelomates are characterized by
A) the absence of a brain.
B) the absence of mesoderm.
C) deuterostome development.
D) a coelom that is not completely lined
with mesoderm.
E) a solid body without a cavity
surrounding internal organs.
3.ANS: E
Animals that do not have a body cavity
surrounding internal organs are said to
be acoelomate. A gastrovascular cavity
is not a coelom. It acts as a digestive
cavity in certain organisms.
Diagrammed above are the steps thought to have led to
evolution of multicellular animals.
Lets look at a brief video overview of the invertebrates…
Clade Parazoa or
sponges-Most closely
related to colonial
choano-flagellates. These
protists and animals have
a common ancestor.
Phylum Porifera
1. Sessile with no
specialized tissue i.e.
nerves or muscle.
2. Size 1 cm-2 m. Mostly
marine species with few
freshwater. The body of a
sponge has a cavity called
a spongocoel. The body is
perforated with pores.
4. The distinction between the sponges
and other animal phyla is based mainly on
the absence versus the presence of
A) a body cavity.
B) a complete digestive tract.
C) true tissues.
D) a circulatory system.
E) mesoderm.
4. ANS:
C
Sponges do not have true tissues. Tissues are
composed of a group of cells with a common
function such a muscles or nervous tissue.
5.Which two main clades branch from the
earliest Eumetazoan ancestor?
A) Porifera and Bilateria
B) Porifera and Cnidaria
C) Cnidaria and Bilateria
D) Rotifera and Deuterostomia
E) Deuterostomia and Bilateria
5. ANS: C
The two main clades that branch from
the Eumetazoan ancestor are the clades
Cnidaria and Bilateria. Both of these
clades have true tissues.
Water flows into the pores and into the spongocoel and then out a
larger opening called the osculum. There are two layers of cells with
a gelatinous layer in between called the mesophyl. The outside of the
body is lined with epidermal cells.
3. The pores are lined with cells (porocytes). The inside layer is lined
with cells (choanocytes like choanoflagellates ). The flagella of
choanocytes beat creating a water current. The choanocyte cell has a
collar with a flagella. It also secretes mucus to filter and catch food.
There are also amoebocytes which take food from the choanocytes
and deliver it to the epidermal cells.
4. Sponges are hermaphrodites. Gametes come from amoebocytes
and choanocytes. Eggs reside in the mesohyl and sperm from
neighboring sponges fertilize them.
6.Water movement through a sponge would
follow what path?
A) porocyte -> spongocoel -> osculum
B) blastopore -> gastrovascular cavity ->
protostome
C) choanocyte -> mesohyl -> spongocoel
D) porocyte -> choanocyte -> mesohyl
E) collar cell -> coelom -> porocyte
6.ANS: A
Water movement through a sponge
follows the pathway of porocyte ->
spongocoel -> osculum
Clade Eumetozoa-Animals with true tissues. Two clades are found
in Clade Eumetazoa-Clade Radiata and Clade Bilateria
Clade Radiata-Animals with radial symmetry (top and
bottom with no head or rear end). Radiata has two tissue
layers ectoderm and endoderm and no mesoderm resulting in
dipolblastic embryos (no mesoderm).
Phylum Cnidaria-Jellyfish and hydra-The basic body plan is a sac
with a gastrovascular cavity (GVC). The single opening
functions as both the mouth and the anus. Two variations of
this body plan-the polyp and medusa. The polyp is a cylinder
form that is sessile and adheres to the bottom of the water.
The medusa is a "flattened-version of the polyp upsidedown". It moves in the water by drifting and contracting its
bell shaped body.
7. Although a diverse group, all
cnidarians are characterized by
A) a gastrovascular cavity.
B) an alternation between a medusa and
a polyp stage.
C) some degree of cephalization.
D) muscle tissue of mesodermal origin.
E) the complete absence of asexual
reproduction.
7. ANS: A
All the cnidarians have a gastrovascular
cavity. There is no cephalization (some
form of head). There is some
contractile tissue but is does not
originate from the mesoderm. Some
cnidarians show alternation between
medusa and polyp stage but other lack
one or the other. Some cnidarians do
have some form of asexual
reproduction.
Some species exists as
polyps and others as
medusas and others
will have both forms
in their life cycles.
Both forms have two
layers of tissue with a
gelatinous layer of
material in between
called the mesoglea.
Surrounding the
mouth of these
animals are a ring of
tentacles.
These tentacles have stinging cells called cnidocyte cells. These cells
have poisonous, little dart like structures called nematocysts. No
muscles but cell will bundles of contractile fibers.
There is also nerve net that can detect stimuli causing the organism
to react. The gastrovascular cavity has specialized cells that release
digestive enzymes to aid in digestion.
Class Hydrozoa-(Portuguese man-of-war, hydras, some corals).
Mostly marine. Both medusa and polyp forms present. Polyp form
usually colonial.
Class Scypphozoa-(jellies, sea nettles). All marine. Polyp form
greatly reduced. Medusa form up to 2 m in diameter.
Class Cubozoa-(box jellies,and sea wasp) All marine. Polyp form
greatly reduced. Medusa forms a box like shape with complex eyes
and potent venom.
Class Anthozoa-(sea anemones, most corals, and sea fans). Medusa
stage completely absent sessile, many colonial.
Phylum Ctenophora-Superficially looks like cnidarian medusas.
These are the comb-jellies. Small and sperical or ovoid. 8 rows of
comblike plates fused cilia.
Clade Bilateria- These animals have bilateral symmetry. Gives
animals dorsal and ventral side as well as an anterior (head) and
posterior (tail) end. Cephalization occurred or movement of sensory
organs to the anterior end. The anterior end is first to encounter
danger, food and other important stimuli.
This clade divides up three smaller clades, Deuterostomia,
Lophotrochozoa, Ecdysozoa
The first clade are the deuterostomes. The deuterostomes are
characterizied by their embryonic development and formation of a
deuterostome.
The second clade are the lophotrochozoans either has a lophophore
(a crown of ciliated tentacles function in feeding) or the
development of a trochophore larva.
8. The diagram above illustrates a larval
form that is characteristic of
A) Clade Bilateria B) Clade Eumetazoa
C) Clade Lophotrochozoa D) Clade
Animalia
8. ANS: C
In the Clade Lophotrochozoa, there is
either trochophore larva or the
organism has a lophophore (a crown of
cillia).
The third clade is Ecdysozoa. These are animals that form an
exoskeleton or thick cuticle. As the animals grow they molt or shed
their outer covering (ecdysis).
Clade Lophotrochozoa
Phylum Platyhelminthes: Flatworms
a. Have gastrovascular cavity with
pharynx as mouth on ventral side
b. Acoelomates
c. Nervous system is a pair of ventral
nerve cords. Can have eye spots on
anterior end that responds to light. In
the anterior region one can find a
ganglion.
d. Nitrogenous wastes removed by a
“flame cell” system
Four Classes found in this phylum
Class Tubellaria-Mosly free-living, most marine,
few terrestrial, predators, scavengers; body surface
ciliated.
Class Mongenea- Marine and freshwater parasites
on external surfaces of fish.
Class Trematoda- Flukes are parasites of
vertebrates. Complicated life history witn
intermediate host.
Class Cestodea-Tapeworms with scolex. No head or
digestive system. Complicated life history.
9.
Which of the following will this organism not
have?
A) true coelom
B) nervous tissue
C) gastrovascular cavity
D) flame cell system
9.ANS: A
This organism does not have a body cavity
surrounding its organs and is considered
to be acoelomate. It does not have a
true coelom.