Animal diversity

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The Evolution of
e o ut o o
Animal Diversity
AP Biology Rapid Learning Series
Wayne Huang, PhD
Andrew Graham, PhD
Elizabeth James, PhD
Casandra Rauser, PhD
Jessica Habashi, PhD
Sara Olson, PhD
Jessica Barnes, PhD

www.RapidLearningCenter.com/
© Rapid Learning Inc. All rights reserved.

© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com

1


Learning Objectives
By completing this tutorial, you will learn about:

Animal origin
Animal Diversity
Animal Evolution
Cambrian Explosion
Animal Classification

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Animal Evolution – Concept Map
Sponges

Colonial Protists

Bilaterally symmetrical
flatworms

Pseudocoelomes

Most likely
ancestor
Most likely
ancestor

Animals

Coeloms

Coelom from Hollow outgrowth

Radially symmetrical
cnidarians

Coelom from mass of
cells

Mollusks
Annelids
Arthropods

Echinoderms
Chordates
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2


Animal Origin

Introduction
Characteristics of Animals
Basic Features
Animal Organ Systems
Animal Body Fluids
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Introduction Animal Diversity
Comparisons are
made by
determining the
characteristics of
extinct animals
with living
animals.

Evolution is the
continuous genetic
change in
organisms as a
i
result of selection
acting on their
adaptation to an
environment.

Animals are
heterotrophic.
This means they
need organic
substrates to grow
and develop.
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3


What is an Animal?
1. Animals are eukaryotic and
multicellular.
2. They are heterotrophs without a cell
wall.
3. Life cycle of animals include a diploid
adult that produces eggs or sperms
by meiosis.
4. They are responsive to their
environment.
5. The body of animals become fixed as
they develop although some undergo
metamorphosis later on.

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Characteristics of Animals
Animals have
distinct types of
cell junctions.

Animals are
composed of diploid
cells with the
exception of gametes
which are haploid.

All animals go through
embryonic stages that include
the blastula and gastrula.
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4


Basic Features of Animals

Animals are
characterized by
diploid cells.

Animals develop
from embryos.

Sexual reproduction

Animals have the
ability to develop
motile sperm and
non motile eggs.

Capable of complex and
rapid movement.

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Animal Organ Systems
Skeletal

Muscle
Excretory
Hormones
Nervous

Sensory

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5


Animal Body Fluids
Animals are able to
move their body fluids,
e.g. circulation by heart
through the blood
vessels.

Yes, and the respiratory
system can move and
exchange O2 and CO2.

And the
excretory
system moves
urine and feces.

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Animal Diversity

Introduction
Splitting f Ph l
S litti of Phyla
Parazoa Vs. Eumetazoa
Radiata Vs. Bilateria
Acoelomates Vs. Coelomates
Protosomes Vs. Deuterosomes
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6


Introduction to Diversity
Most animal phyla are
invertebrates, i.e. they
don’t have a backbone.

There are about 35 animal phyla.
There is an abundance in the
number of species in any given
location.
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Splitting of Phyla
Phyla are split according to their adult
and embryological forms into

Parazoa Vs. Eumetazoa

Protosomes Vs.
Deuterosomes

Radiata Vs. Bilateria
Acoelomates VS Coelomates
VS.

Example
Nematode

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Diploblastic Vs. Triploblastic


7


Parazoa vs. Eumetazoa
First splits in evolution
Eumetazoa:

Parazoa:
Do not have tissues
and body parts are
primitive. The only
surviving members
are sponges.

Well developed
tissues and
organs

First split

Split between animals lacking true tissues

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Phylum porifera are the only extinct members of the
Parazoa.

Radiata vs. Bileria
Radiata-bilateria split in early evolution
Radiata Vs. Bilateria split

Radiata

Animals with radial
symmetry and are
diploblastic.
Ex: Phylum cnidaria

Bilateria

Bilateria are all other
animal groups which are
bilateral symmetric and
are triploblastic

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8


Animal Symmetry
Body symmetry

Many animals, such as humans, are symmetrical.
One side of their body is a mirror image of the other side.
But other animals are asymmetrical.
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Characteristics of Radiata
Animals with radial
symmetry posses a
top and bottom,
p
,
there is no distinct
front, rear or sides
Most radial
animals are
sessile
organisms or
planktonic
(drifting or
swimming
aquatic forms)

Radiata Animal
Most active
animals are
generally
bilateral

All
members of
radiata are
also
diploblastic

The radial
symmetry
enables
adaptation
to
environment

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9


Characteristics of Bilateria
Bilateria
animals have all
sides present,
such as a top,
bottom, rear,
front and sides.

Radial symmetry of
y
y
some animals is
associated with an
adaptation to a
sedentary lifestyle

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All members of bilateria
are also triploblastic.

Bilateral symmetry is associated
with cephalization - an
evolutionary trend to concentrate
sensory organs on the anterior
end.
end This enables the animal to
sense danger, food, etc.

Forms of bilateral symmetry can have heads.

Acoelomates vs. Coelomates
Acoelomate animals, like
flatworms have no body cavity
the organs have direct contact
with the epithelium.

Acoelomates: animals
with no coelom (body
cavity).

Coelomates animals have a “true
coelom” or body cavity that is
fluid filled and lined with a
peritoneum.

Most bilateral animals, including
vertebrates are coelomates.

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10


Acoelomates
Flatworms are the simplest
bilateral animals, phylum:
Platyhelminthes.

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Cnidarians
Cnidarians exhibit radial symmetry

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11


Protostomes vs. Deuterostomes
Protostomes together with
deuterostomes and a few
smaller phyla make up the
Bilateria.

In protostomes the first opening
in development, the blastopore
becomes the animal’s mouth. In
deuterostome it becomes the
anus.

Deuterostomes are
enterocoelous, meaning the
folds of the archenteron form
the coelom.

Protostomes are
schizocoelomates meaning
a solid mass of embryonic
mesoderm split to form a
coelom.

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Advantages Having a Coelom
.

The advantage of
having a coelom
include that there is
room for growing
internal organs.
i t
l

Muscles can
increase
contraction and
move fluid around.

Have a circulatory
system and fluids
can transport
nutrients
throughout the
organisms.

Leads to development of
the digestive system
which is not dependent
on other organs.

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12


Animal Evolution
Introduction
Gastrulation
G t l ti
Animal Embryology
Animal Birth
Evolution
Diploblastic & Triploblastic Animals
25/53

Introduction Animal Evolution

Sir Darwin,
,
embryological
changes take place
during evolution.
Why is that
important?

I noted in “The Origin of Species”
“That we can see why
characteristics derived from the
e b yo should
embryo s ou d be of equal
o equa
importance with those derived
from the adult, for a natural
classification includes all
stages.”

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13


Gastrulation
Gastrulation is an invagination of cells during the blastula
phase of development to form a digestive cavity – called
archenteron and two separate germ layers called an ectoderm
and (internal endoderm) often a mesoderm develops between
them.
them
There is only one opening to
the digestive cavity which is
known as the blastopore.
The germ layers differentiate to
form tissues and organs.

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Animal Embryology
Early embryological development
Zygote
Eight cell
stage
Cleavage

Cleavage

Blastula
(hollow ball)

Blastococi
Cleavage
Gastrula
Blastocoels
(Ectoderm
Endoderm
Mesoderm)
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14


Development of Multicellular Organisms
Development of multicellular
organisms likely occured
with colonial protists. These
were collection of identical
cells.
ll

This is thought to have
evolved into a hollow ball of
nonspecific cells eventually
cell specialization would
have developed.

Following specialization
there would have been some
in folding and gastrula like
proto animals.

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Features of Evolution
Bilaterally symmetrical animals produce three germ layers
The evolution of tissues
involved cell
specialization. The
evolution of bilateral
symmetry allowed
organization of body
parts, including
cephalization, and
increased motility.

Ectoderm

Endoderm

Mesoderm

Three basic types of body plans
Acoelomates with no body cavity
Pseudocoelomates with a
cavity between the
mesoderm and endoderm

Coelomates with a fluidfilled body cavity entirely
within the mesoderm.

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15


Animal Germinal Layer Evolution
Lets have a closer look at the
germinal layer of the blastocyst.
The development of specialized
layers was critical for the
y
evolution of animals with
specialized tissues and organs.

Mesoderm becomes
muscle, skeletal and
connective tissue.
Endoderm
becomes the
digestive gut.
Ectoderm becomes the outer
surface and nervous tissue of
animals.

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Diploblastic Animals
Diploblastic animals are
those in which the ovum has
two primary germ layers: the
ectoderm and endoderm.

Diploblastic organisms
evolve from this kind of
ovum and include cnidaria
and ctenophores. The
ctenophores
endoderm allows them to
develop true tissue.

Cnidaria

Ctenophores

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16


Triploblastic Animals
Triploblastic
animals have 3
ge
germinal layers.
a aye s
Chordata

Rotifera uses solar
energy.
Lets look at some
examples of
triploblastic animals.

Arthropoda

Platyhelminths

Rotifera

Mollusca

Nematoda

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The Cambrian
Explosion
Introduction
Cambrian Explosion
Explosive Evolution
Expansion of Animal Diversity
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17


Introduction to Cambrian Era

About 500 million years
ago, extinct animals were
identified in fossil records

All surviving
i i
animals today can
be traced back to
their ancestors to
this time period.

Soft body fauna species have been
dated back to 700 million years,
but lacked sophistication and
resembled acoelomates

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Cambrian Explosion
Development of hard body
parts such as teeth which
resulted in a more
sophisticated diet, both as
preditor and prey.

Hard body parts were easily
identified from fossil records.

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18


Explosive Evolution

Flagellated cells
Hollow spherical colonies
Suspended in water
Specialized cells with
somatic functions

Differentiated entity
with infolded temporary
digestive tract

Proto animals with
completely infolded
two layered
wall
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Expansion of Animal Diversity
Diversity also developed
due to genes assisting in
embryonic development.

Animal diversity developed due to
increased dependency on the
predatory/prey relationship.

And also because
of the development
of adequate
environment
oxygen to support
active animal life
style.

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19


Animal
Classification
Phylum and rules of classification are introduced.

39/53

Animal Evolution: Process

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20


Phylum Porifera: Sponges
Most are marine and live singularly,
attached to a substrate, and range in
height from 1 cm to 2 m.

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Phylum Cnidaria: Coelenterates
Cnidarian show
radial symmetry.
Examples include
Sea Anemones,
Jelly fi h H d
J ll fish, Hydra.

In the form of a polyp (relatively
fixed in position) or a medusa
(swimming)

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21


Phylum: Platyhelminthes Flatworms
There are three major groups of
flatworms: Free-living planarians that
live on rocks in marine and fresh water,
parasitic flukes and tapeworms
flukes,

43/53

Phylum Nematoda: Roundworms
Pseudocoelomates
have a false body
cavity.

Body cavity lined on
inside by endoderm and
outside by mesoderm.
The false cavity is used
to give animals its shape.

Examples include
hook, ascaria, pin
and filarial worms.

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22


Phylum Mollusks
True circulatory system.
Bilateral symmetry,
complete digestive tract,
coelom and internal organs
g

Outgrowth of body
surface that
functions as a shell,
sensory reception
and houses gills

Common body plan

Muscular foot and a
mantle.
Ex: Clams, scallops,
and oysters.

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Phylum Annelida: Segmented Worm
Segmentation is subdivision
of body in repeat parts. The
phylum is also characterized
by, nervous, circulatory and
excretory systems.

Earthworms have
repeating
segments.
Segmentation
provides body
flexibility and
mobility.
Ex: Earthworm,
leech, marine worm
called polychaetes.

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23


Phylum Arthropoda: Insects
In terms of diversity,
geographical distribution
and numbers, arthropoda
numbers
is the most successful
phyla.

Arthropods are segmented,
have jointed appendages
and have an exoskeleton
composed of chitin.

To grow, arthropods molt their
exoskeleton, swell in size
and secrete a new
exoskeleton.

Arthropoda have a
skin/exoskeleton.
Examples include:
Insects, Crustaceans,
Arachnids, millipedes and
centipedes

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Phylum Echinodermata: Echinoderm
Many possess a well
developed skeleton with
numerous spines that
extend outward to give
the animal a spiny
appearance.
A unique feature is their
water vascular system.

Slow moving animal
with a thin skin that
covers an
exoskeleton-includes
sea urchins, brittle
stars.

Examples include: Sea
urchins, starfish, brittle
stars, sea cucumbers are
exclusively marine animals.

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24


Phylum Chordata: Vertebrates
Most important subgroup is
vertebrata – animals that have a
backbone or a vertebral column.
Humans belong to this phylum.

Includes major groups of
vertebrate animals:
cartilaginous fish, bony fish,
amphibians, reptiles, birds
and mammals.
mammals

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Question: Review
_____ means that animals
require organic substrate to
grow and develop.

___________
Heterotrophic

The life cycle of animals
include an adult ____ somatic
cells.

___________
Diploid

Blastula and gastrula are
____ stages.

___________
Embryonic

Animals have _____ sperm
and ______ eggs.

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Radial symmetry in animals
is called.

___________
Motile, non-motile
___________
Bilateria


25


Learning Summary
Parazoa do not have
true organelles and
body parts are
primitive.
i iti
Eumetazoa have
well developed
tissues and organs.

Eukaryotic,
multicellular
heterotrophs have
sensory,
sensory
respiratory,
excretory and
skeletal systems.

Arthropods are the
most successful of
all phyla and have
joint appendages
and exoskeleton.

In protostomes the
first opening in
development, the
blastopore
becomes the
animal’s mouth. In
deuterostome it
becomes the anus.

Embryonic stages
include formation of
zygote, blastula and
gastrula
Gastrulation - mode
of development
leading to animal
differentiation.

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Congratulations
g
You have successfully completed the
core tutorial
The Evolution of Animal Diversity


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26


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Animal diversity

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