Download Introduction to Animal Diversity

Introduction to Animal
Diversity
Packet #76
Chapter #32
Animal Diversity
 Biologists have identified 1.3 million living species
if animals.
 Estimates put the range much higher
 10 – 200 million
 Evolutionists believe that the chanoflagellates, a
colonial flagellated protist, was the start of
Kingdom Animalia.
Characteristics Most Common to Animals
 Eukaryotic
 Multicellular
 Heterotrophic
 Animals use enzymes to digest their food after they
have ingested it.
 Stores energy as fat (long term) or as glycogen
(short term)
Reproduction in Animals
Reproduction—The
Obvious
 Most animals reproduce sexually and have a diploid
stage that is dominant in the life cycle.
 Sperm and egg unite to form a zygote
 Zygote undergoes cleavage
 Multiple cell divisions result in the development of a
hollow ball of cells
 Blastula
 Blastula undergoes gastrulation.
 Embryonic tissues are formed
 Developmental stage is called the gastrula.
Reproduction—The Sometimes Not
So Obvious
 Some animals develop directly into adults
 After transient stages of maturation
 However, life cycle of many animals include larval
stages.
 Larva

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Sexually immature form of an adult
Morphologically distinct
Usually eats different food
Inhabits different areas than the adult
Must undergo metamorphosis to become an adult
Developmental Genes Across
Kingdom Animalia
 Animals share a unique homeobox
 Family of genes
 Hox genes
 The number of hox genes is correlated with the complexity
of the animal’s anatomy.
Categorizing Kingdom
Animalia
 Animals are classified on major features of animal
body plans.
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Symmetry
Tissue Complexity
Cephalization
Body Cavities
Body Plans
Symmetry
Introduction
 There are two types of
symmetry
 Radial Symmetry
 Bilateral Symmetry
Symmetry
 Radial Symmetry
 Describes how the parts of
an animal radiate from the
center.
 Any imaginary slice
through the central axis
divides the animal into
mirror images.
 Sea anemones have a top
(oral, mouth) side and a
bottom (aboral) side.
Symmetry II
 Bilateral Symmetry
 Describes a two sided
body plan.
 Animal has a left side
and right side
 Imaginary slice can only
be placed in one location
in order to divide the
animal mirror images.
 Lobster has a dorsal (top)
side, a ventral (bottom)
side, a left and right side,
an anterior (head) with a
mouth and a posterior
(tail) end.
Symmetry III
 Animals can be categorized according to the
symmetry of their bodies or lack of it.
 Symmetry Reflects Lifestyle
 Radial animals are sessile or planktonic
 Bilaterial animals more actively from one place to
another
 The nervous system enables these organisms to move.
Tissue
Tissue I
 As a young embryo
develops, embryonic tissue,
called germ layers, are
produced via gastrulation.
 There are three germ layers
 Ectoderm
 Endoderm
 Mesoderm
Tissue II
 Ectoderm
 Outer layer
 Gives rise to the body
covering and the nervous
system
 Endoderm
 Inner layer
 Gives rise to the lining of
the gut (archenteron) and
other digestive organs
 Mesoderm
 Middle layer
 Gives rise to most other
body structures.

Including muscle
Diploblastic vs.
Triploblastic
 Diploblastic
 Animals with only two
layers
 Ectoderm and
Endoderm
 Jellies
 Corals
 Comb jellies
 Triploblastic
 Animals with all three
layers
 Include all bilaterally
symmetric animals.
Triploblastic Animals &
Body Cavities
Functions of Body Cavities
 Provides protection to internal organs
 Allow organs to grow and move independently of
the outer body wall.
Body Cavity I

Triploblastic animals have
traditionally been classified as
 Acoelomates [ey-see-luh-meyt]
No body cavity
Lack a coelom. [see-luhm]
Pseudocoelomate [soo-dohsee-luh-meyt, -si-loh-mit]
 Body cavity not completely
lined with mesoderm
 Body cavity formed from the
blastocoel.
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


Coelomate



True coelom
Body cavity completely
lined with mesoderm.
Cushions the internal organs
and protects them.
Formation of the Coelom
[see-luhm]
 Coeloms can be divided
into two categories based
on how it is developed.
 During gastrulation,
developing digestive tube
forms the archenteron.
 Protostomes
 Development of the
coelom forms from splits in
the mesoderm

Schizocoelous Development
 Deuterostomes
 Development of the
coelom forms from
outpocketing of the
mesodermal tissue of the
archenteron.

Enterocoelous Development
The Coelomates
Introduction I
 Protostomia
 Mollusks
 Annelids
 Arthropods
 Deuterostomia
 Enchinoderms
 Chordates
Protostomes
 Blastopore develops into
the mouth
 Undergo spiral and
determinate cleavage
 Spiral cleavage

Describes how the planes
of cell division are
diagonal to the vertical
axis of the embryo.

Smaller cells lie in the
grooves between larger,
underlying cells
 Determinate cleavage

Indicates that the
developmental fate of each
embryonic cell is
determined at fertilization.

If cell is isolated it will
form an inviable embryo.
Deuterostomes
 Blastopore typically
becomes the anus.
 Undergo radial and
indeterminate cleavage.
 Radial cleavage
 Cleavage planes are
either parallel or
perpendicular to the
vertical axis of the egg
 Indeterminate cleavage
 Each cell produced by
early cleavage divisions
has the capacity to
develop into a complete
embryo.
Protostomes vs.
Deuterostomes
Review
Symmetry
Symmetry
Radial
Symmetry
Bilateral
Symmetry
Sea
anemones
Lobster
Tissue
Germ
Layers
Ectoderm
Mesoderm
Endoderm
Outer layer
Middle
layer
Inner Layer
Body
Covering
Nervous
System
Muscle
Other Body
Structures
Lining of
Gut
Digestive
System
Germ Layers  Body
Cavity
Body Cavity
Diploblastic
Triploblastic
Acoelomates
Psuedocoelomates
Protostomes
Coelomates
Deuterostomes
Body Cavity
Coelomates
Protostomes
Blastopore 
Mouth
Spiral Cleavage
Deuterostomes
Determinate
Cleavage
Blastopore 
Anus
Radial Cleavage
Indeterminate
Cleavage