Download The Animal Kingdom

Animals: An Introduction
Characteristics of Animals
 All
are multicellular
 All are heterotrophic
 Most are motile, (can move), at
least some part of life cycle
 Most undergo a period of
embryonic development during
which 2 or 3 layers of tissues
form
What is an animal?
- Multicellular
- Need water, food, and oxygen to survive
- Heterotrophs
* Carnivores (Predators of Prey)
(Eat other animals)
* Herbivores (Eat plants)
* Omnivores (Eat plants and other animals)
How the first animals might have
evolved from unicellular organisms

Scientists have inferred that multicellular
invertebrates may have developed from
colonies of loosely connected,
flagellated protists (b/c protists are
heterotrophic and eukaryotic)
The “Backbone” of Animal Classification
95 % Invertebrates (No backbone)
- jellyfish, worms, snails, spiders, insects)
5 % Vertebrates (Backbone)
– fish, amphibians, reptiles, birds, mammals)
Two kinds of tissue found only in animals:
1. Nervous tissue
2. Muscle tissue
The Nature of Animals (Kingdom Animalia)
Invertebrates = 95% of all animals Vertebrate an
animal with a backbone (5% of animals)
- Vertebrata is a subphylum of the phylum
Chordata
- Vertebra one of the repeating bony units of the
backbone
 Animals are Multicellular
- specialization the differentiation of a cell for a
particular function
- cell junction connection between cells that holds
them together as a unit
 Heterotrophy requires ingestion the taking in of
organic matter

The Nature of Animals
(Kingdom Animalia) cont…



Sexual Reproduction and Development:
- Sexual reproduction = two haploid gametes
fuse into a zygote
- zygote the first cell of a new individual in
sexual reproduction
Development causes the cells to undergo
differentiation
- differentiation a process through which
cells become different from one another
Movement is made possible by two tissue types
(muscle and nervous tissue)
- Nervous tissue perceives signals from
stimuli
- neuron a cell that transmits electrical
signals
- muscle tissue receives nerve impulses and
responds to the stimuli
Symmetry & Body Direction
When studying and describing animals, some basic
body characteristics are important. These include:
Animal Body Symmetry - the way body parts are
arranged around a center point.
(Asymmetry, Bilateral Symmetry, Radial Symmetry)
Directions on the body - used to describe areas on
the body of an animal.
(Dorsal, Ventral, Anterior, Posterior)
*segmentation = a series of repeating similar units
Ex. Phylum Annelidia, Phylum Arthropoda, Phylum
Chordata
Asymmetry = no symmetry
Bilateral and Radial Symmetry
• Cephalization = concentration of nerve tissue and
sensory organs at the anterior end of a bilateral organism
Directions on an animal body:
Dorsal
top surface
Anterior
front end
Posterior
hind end
Ventral
bottom surface
Animal Diversity
Animalia
- Invertebrata =
(10 major phyla)
- Chordata =
(11th major phylum)
* Vertebrata =
a subphylum
Features found only in chordates

1.
2.
3.
4.
At some stage of development, all
chordates have …
Notochord = firm, flexible, dorsal rod of
tissue
Dorsal nerve cord = hollow tube
Pharyngeal pouches = small out pockets
of the anterior part of the digestive tract
Postanal tail = muscle tissue behind the
posterior opening of the digestive tract
How chordate characteristics change
during development
Humans:
 Notochord = backbone
 Dorsal nerve cord = spinal cord and
brain
 Post anal tail and pharyngeal pouches
disappear

Eleven
Major
Animal
Phyla
Coelomates
Pseudocoelomates
Acoelomates
Fertilization:
Sea Urchin Fertilization (sperm & egg)
Structural features taxonomists use to
classify animals
Presence of tissue
 Number of germ layers
 Presence and type of body cavity
 Presence of other features such as a
backbone

Animal Tissue Development
Germ tissue layers produce adult organs
 Endoderm = develops into gut lining
 Mesoderm = develops into muscles
and internal body linings
 Ectoderm = develops into skin
Fertilization and Development steps
through gastrulation:
Fertilization : union of egg and sperm
produces a zygote
 Cleavage process: one divides
repeatedly to form a blastula
 Blastula = a hollow ball of cells with a
blastocoel as a central cavity
 Gastulation forms a gastrula

Embryonic Development
• Zygote = a fertilized egg cell. The
zygote then begins to divide and
eventually forms a hollow sphere of
cells. (called a blastula)
• The blastula continues to grow
through cell division and an
indentation forms into the sphere.
(The embryo is now called a gastrula)
Three primary germ layers of a
gastrula
1.
2.
3.
Archenteron – forms the throat passage,
including the gills or lungs, and the gut
and its associated organs, such as the
liver and pancreas
Ectoderm – forms the outer layer of skin,
hair, nails, and nervous system
Mesoderm – forms the skeleton,
muscles, inner layer of skin, circulatory
system, & the lining of the body cavity
Two functions of the body cavity in
animals
1.
2.
3.
Provides a firm base against which
muscles can contract
Allows the interior of an animal to move
somewhat independently of its exterior
The body cavity acts as a reservoir and
transport medium for substances in the
body
Acoelomates:
The flatworm (planarian) is an acoelomate because it
does not have a coelom within its mesoderm layer. Its
digesitive cavity is surrounded by the endodermal layer.
Pseudocoelomates:
Roundworms (Nematoda) and rotifers (Rotifera) have a
body cavity (coelom) where organs are found and that
can serve as a hydrostatic (fluid-filled) skeleton. Their
coelom is called a pseudocoelom because it is not
completely lined by mesoderm.
Coelomates: with a true coelom
Coelomates: with a true coelom
All complex animals have a true coelom, including the
mollusks, annelids, arthropods, echinoderms and
chordates. They have a true coelom that is completely
lined by the mesoderm layer. The internal organs in a
true coelom are more complex, and they are held in
place by mesentaries.
In other words, the coelom (white) is completely
enclosed within the mesoderm layer (blue).
Coelomates have more complex internal organs and a
muscular gut (intestines) derived from the mesoderm.
Indirect Development
Body Systems
 Animals
have different systems
in their bodies to take care of the
different jobs that allow them to
live and function.
 We will study the diversity of the
animal kingdom by learning
about each of these systems and
how they function from the
simplest of animals to the most
complex.
Systems & Functions
System – provide
protection, support, & motion.
This will also include muscular
systems.
 Skeletal

Digestive System - break down
the food taken into the body.
Excretory System - As animals perform
their various metabolic processes,
protein and nucleic acid, both of which
contain nitrogen, are broken down
 Ammonia – most toxic; excreted by
aquatic organisms
 Uric acid- Highly concentrated;
excreted by reptiles, birds, and insects
 Urea- Least toxic; excreted by
mammals, amphibians, and some fish

Digestive system – break down the food
taken into the body
- sponges digest food with individual cells
- Cnidarians digest food in a central
chamber
- All other invertebrates and vertebrates
have a gut (or digestive tract) where food
is broken down and nutrients are
absorbed by specialized cells that line the
gut


Respiratory Systems –
involve the exchange of
gasses into and out of the
animal. O2 in; CO2 out.
Circulatory Systems –
Distribute food & oxygen
throughout the body and
collect cellular wastes. The
immune system will also be
part of this study.
 Open or closed circulatory
system

System – Collects
information from the environment and
coordinates responses to the
environment.
 Nervous
System – Can function
in several ways: binary fission,
budding, or sexually.
 Reproductive
Patterns of Development
 Protostome Development
- Spiral Cleavage of cells
- Schizocoely formation of mesoderm
 Deuterostome Development
- Radial Cleavage of cells
- Enterocoely formation of mesoderm
Patterns of Development
Protostome ex. Most invertebrates except
Echinoderms
 Spiral cleavage = cells divide in a spiral
arrangement
 Schizocoely formation of the mesoderm =
“split body cavity” the mesoderm forms by
rapid division of the cells that lie at the
boundary of the endoderm and ectoderm

Patterns of Development
Deuterostome – Echinoderms and all
chordates
 Radial cleavage – cell divisions are at
right angles to the axis form one pole of
the blastula to the other
 Enterocoely – “gut body cavity” the
mesoderm forms by rapid division of
cells that line the dorsal part of the
blastopore

Protostome
Spiral Cleavage
Schizoceoly
Deuterostome
Radial Cleavage
Enterocoely