1 I Concept 321 What is an Animal 2 95 are invertebrates Multicellular Eukaryotic Heterotrophic ingestive Lack cell walls Most are mobile Diploid with haploid gametes Sexual reproduction zygote ID: 932434
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Slide1
CHAPTER 32
AN INTRODUCTION TO ANIMAL DIVERSITY
1
Slide2I.
Concept 32.1: What is an Animal?
2
95% are invertebrates
Multicellular
Eukaryotic
Heterotrophic (
ingestive
)
Lack
cell
walls
Most are mobile
Diploid with haploid gametes
Sexual reproduction (zygote
blastula
gastrula
)
Slide3Embryology--Cleavage
3
Slide44
9. Carbohydrates stored as glycogen
10. Some
produce larva which undergo metamorphosis
11. Specialized systems
12. Two unique types of tissue:
nervous tissue
and muscle tissue
13. Share the unique
homeobox
-containing family of regulatory genes know as
Hox
genes
Hox
genes play an important role in development of animal embryos
Slide5II.
Concept 32.2: Animal History
A. Common Ancestor
Such a colony is about 0.02mm high.
5
1. May have resembled modern
choanoflagellates
2.
Choanoflagellates
are
protists
that are the closest living relatives of animals and were probably a colonial, flagellated
protist
.
Slide66
Slide7III. Concept 32.3: Body Plans
7
A. Phylogeny
Define as the evolutionary history of species
Based on general features of morphology and development
Each major branch represents a
grade
, (group of animal species that share the same level of organizational complexity)
A grade is not necessarily a
clade
or
monophyletic
group.
Slide8ANIMALS
8
Metazoa
Parazoa
Eumetazoa
Radiata
Bilateria
Acoelomate
Pseudocoelomate
Coelomate Deuterostomes Protostomes
Slide99
B. Major Branches of the Animal Kingdom
1.
Subkingdom
Parazoa
Simple anatomy (lack true tissues)
Phylum
Porifera
2.
Subkingdom
Eumetazoa
True tissues
All other phyla
Slide1010
C. Body Plans
A
body plan
is a set of morphological and developmental traits
1.Symmetry
Animals can be categorized by body symmetry or the lack of it
a. Radial symmetry (
Radiata
)
-Characterized
by a body shaped like
a pie
or
barrel
, with many equal parts radiating outward like spokes of a wheel -have oral and aboral sides but no
front, back
,
left, or right surfaces
11
b. Bilateral symmetry (
Bilateria
)
-Characterized
by a body form with a central
longitudinal plane
dividing the body into two
equal
but opposite halves
-A dorsal (top) and ventral (bottom) sides
-Anterior (head) and posterior (tail) ends
-Left and
right
sides
-Exhibit cephalization (concentration of nerves and sense organs on anterior end)
Slide12SYMMETRY
12
Slide132. Tissues
a. Tissues
are collections of specialized cells isolated from other tissues by membranous layers
b. During
gastrulation
(downward and
inward movement
of cells
of
blastula
),
three germ layers
form which give rise to the tissues and organs of the animal embryo
13
Slide1414
c.
Diploblastic
Tissues
develop from two germ layers
(ectoderm or endoderm)
d.
Triploblastic
Tissues develop from three germ layers:
Ectoderm
is the outer
most
germ layer which develops into
outer layer and
central nervous system
Endoderm is the inner most germ layer and lines the developing digestive tube called the archenteronMesoderm is the middle layer which is located between ectoderm and endoderm
Includes all
bilaterians
Germ Layers
15
Slide1616
3. Body Cavity (Coelom)
Defined as a fluid- or air-filled space separating the digestive tract from the outer body wall
a.
Acoelomate
No body cavity between digestive tract and
outer
body wall
Area filled with cells
Phylum
Platyhelminthes
Slide17Acoelomate
17
Slide1818
b.
Pseudocoelomate
Body cavity lined with mesoderm and endoderm
Tube within a tube
Phyla
:
Nematoda
Rotifera
Pseudocoelomate
19
Slide2020
c. Coelomate (true body cavity)
Body cavity lined with mesoderm
Mesenteries connect outer and inner mesoderm and suspend internal organs
Phyla
:
Echinodermata
Arthropoda
Mollusca
Chordata
Annelida
Functions of the body cavity
1. Fluid cushions the suspended organs, helping to prevent internal injury
2. In soft-bodied
coelomates
, functions as a hydrostatic skeleton against which muscles can work
3. Enables internal organs to grow and move independently of the other body wall
Coelomate
21
Slide2222
Slide2323
4
. Development--
Protostomia
vs.
Deuterostomia
2 evolutionary lines in
coelomates
Differ in cleavage, fate of
blastopore
, and coelom formation
Protostomes
—mollusks, annelids, arthropods
Deuterostomes
—echinoderms, chordates
Slide2424
a
. Cleavage
Protostomes
Spiral Cleavage
—cleavage diagonal to the embryo’s vertical axis
Deuterostomes
Radial Cleavage
—cleavage either parallel or perpendicular to embryo’s vertical axis
Slide2525
b.
Determination
Protostomes
Determinate Cleavage
—developmental fate of each cell determined very early
-A
cell from 4-cell stage will not
develop
fully
Deuterostomes
Indeterminate Cleavage
—early cells retain ability to develop into complete embryo if isolated from other
cells
-Makes possible identical twins and embryonic stem cells
Slide26Cleavage
26
Slide2727
c
. Coelom
Formation
Protostomes
Schizocoelous
—the splitting of solid masses of mesoderm forms the coelom
Deuterostomes
Enterocoelous
—the mesoderm buds from the wall of the archenteron to form the coelom
Slide28Coelom Formation
28
Slide2929
d.
Fate of
Blastopore
Blastopore
—first opening of
archenteron (gut) which forms
from blastula during
gastrulation
Protostomes
--
Blastopore
becomes the mouth
Deuterostomes --Blastopore becomes the anus
Slide30Fate of the
Blastopore
30
Slide3131
Slide32IV. Concept 32.4: New Views of Animal Phylogeny
32
One hypothesis of animal phylogeny is based mainly on morphological and developmental comparisons
Slide33Morphological Characteristics
33
Slide3434
One hypothesis of animal phylogeny is based mainly on molecular data
Slide35Molecular Studies
35
Slide36A. Points of Agreement
36
All animals share a common ancestor
Sponges are basal animals
Eumetazoa
is a clade of animals (
eumetazoans
) with true tissues
Most animals phyla belong to the clade
Bilateria
and are called
bilaterians
Chordates and some other phyla belong to the clade
Deuterostomia
Slide37B. Progress in resolving
Bilaterian Relationships
37
1. The morphology-based tree divides
bilaterians
into two clades:
deuterostomes
and
protostomes
2. In contrast, recent molecular studies indicate three
bilaterian
clades:
Deuterostomia
,
Ecdysozoa
, and
Lophotrochozoa
a. Ecdysozoans shed their exoskeletons through a process called ecdysis (Arthropoda and Nematoda) b. Some
lophotrochozoans
have a feeding structure called a
lophophore
(
Mollusca
,
Annelida
,
Rotifera
,
Platyhelminthes
)
c. Other phyla go through a distinct developmental stage called the
trochophore larva(Mollusca and
Annelida)
Slide38TERMS:
38
Zygote
Cleavages
BlastulaGastrulaEctoderm
Endoderm
Mesoderm
Blastopore
Archenteron
Metamorphosis
Radial symmetry
Bilateral symmetry
Cephalization
Acoelomate
Pseudocoelomate
Coelomate
Anterior
PosteriorDorsalVentral
Slide39Ecdysis
39
Slide40Trochophore
Larva40
Slide4141
Slide42You should now be able to:
42
List the characteristics that combine to define animals
Distinguish between the following pairs or sets of terms: radial and bilateral symmetry; grade and clade of animal
taxa
;
diploblastic
and
triploblastic
; spiral and radial cleavage; determinate and indeterminate cleavage;
acoelomate
,
pseudocoelomate
, and coelomate grades
Compare the developmental differences between
protostomes
and
deuterostomes Compare the alternate relationships of annelids and arthropods presented by two different proposed phylogenetic treesDistinguish between ecdysozoans and lophotrochozoans