Kingdom AnimaliaThe study of animals
is called Zoology
The Animals have 6 major Characteristics
1. Animals are multicellular ………………..
Except for sponges, animal cells are arranged into tissues (a tissue is a group of cells alike in structure and function… such as muscle tissue or
brain tissue). Tissues are necessary to produce organs and organ systems.
2. Animals are heterotrophs
• Heterotrophs can only consume their foods….. they are not capable of
making their own foods.
3. Animals are diploid• The dominant generation in the life cycle is the
diploid generation. Their gametes are heterogametes (different sizes); eggs are larger than sperm. Gametes are produced by meiosis. A typical animal life cycle is
shown below.
2N
Human Life Cycle
n2n
4. Animals are motile
• Heterotrophy often requires motility (the ability to move) to capture prey. Animals have motility during at least some part of
their life cycle.
5. Animals have a period of embryonic development
• During embryonic development, cells become specialized and form two or three layers of tissues. Tissues are groups of similar cells.
• Cell Specialization allows cells to perform more efficiently than requiring individual cells to
perform many functions. Cell Specialization allows the Division of Labor. Division of Labor.
6. Animal cells lack cell walls
• Therefore a skeleton is necessary to support the tissues of large animals.
The Origin of AnimalsAquatic, Colonial (multicellular), Heterotrophic ProtistsAquatic, Colonial (multicellular), Heterotrophic Protists
Choanoflagellates
The key to the success (survival ) of the Animals is their
Diversity….their variations.The Diversity of the Animals originates from
the variations that occur in their:• 1. Tissue Complexity• 2. Body Symmetry• 3. Cephalization• 4. GastroVascular Cavities (GVC)• 5. Coeloms• 6. Segmentation, and whether they are…..• 7. Protostomes or Deuterostomes.
1. Tissue Complexity
• Most animals, collectively called the eumetozoans, have closely functioning
tissues. Some organisms are diploblastic, have only two cell layers… such as the hydra
and jellyfish. Some organisms are triploblastic and have three cell layers. The
three “germ layers”germ layers” are the ectoderm, mesoderm and endoderm. There is a group
of animals, the parazoans (sponges) that are not organized into true tissue and lack
organs.
The Embryonic “Germ” Layers
• The three layers of tissues that become established during early embryonic development are called germ layers. They give rise to the body tissues.
These three layers are called….. 1. ectoderm, 2. mesoderm, and
3. endoderm.
The Embryonic Germ Layers develop from the Blastula….. Gastrula
Hollow ball of cells stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and
endoderm surrounding an
archenteron
(opening)
archenteron
Gastrula
The Embryonic Germ Layers• The ectoderm forms from the
outer layer of cells. It gives rise to the skin, hair, nails and
nervous system. • mesoderm forms between
the ectoderm and endoderm. It becomes the muscles,
connective tissues, skeleton, kidneys, circulatory and
reproductive organs.• The endoderm made of cells
that form the tube-like structure in the gastrula.
These cells will form the lining of the GVC and the major
organs of the digestive system.
2. Body SymmetryThere’s 3 basis shapes…1. asymmetry, 2. radial
and 3. Bilateral symmetry
Asymmetry
• Asymmetrical animals have no
pattern of symmetry. The simplest animals
(sponges) are asymmetrical.
Radial Symmetry
• The body parts of a radially symmetrical animal are arranged
around a central axis so that each part extends
from the center. Animals that exhibit
radial symmetry tend to be sessile (immobile).
Radial symmetry allows them to reach out in all
directions.
Bilateral Symmetry• Only one cut along the
longitudinal axis will produce identical halves of a
bilaterally symmetrical animal. Bilateral symmetry is
best for motile animals.• Body Plan Includes
• Anterior (head) and Posterior (tail) ends
• Dorsal and Ventral surfaces• “Right” and “Left” sides are
mirror images
Longitudinal A
xis
Sponges Sea Anemone Humans
3. CephalizationThe term “Cephalo” means “head”.
In animals with bilateral symmetry, there is a
greater increase in the nerve tissue
concentrated in the anterior end (the head) as animals increase in
complexity. For example, brains have
formed with accessory organs for seeing,
hearing, tasting, etc.
4. Gastrovascular Cavity (GVC)
GastroVascular Cavities (GVC) are areas
where food is digested. If they have only one opening, the processing is limited.
Two openings designate a digestive tract allowing food to
be digested more thoroughly.
Gastrovascularcavity
5. Body Cavities
• The body cavity is a space that separates the gut and internal organs
from the rest of the body.
• It isolates the internal organs from body-wall movements.
• It also bathes the internal organs in a liquid through which nutrients and
wastes can diffuse.
The Arrangement of the Ectoderm, Mesoderm, and Endoderm
An acoelomate is an animal which does not have a coelom. A coelom is a body cavity which is
completely lined with mesoderm.
Digestive cavity
Flatworms are Acoelomates
A pseudocoelomate animal has a body cavity (called a pseudocoelom) located between
endoderm and mesoderm.
pseudocoelom
Digestive cavity
Roundworms are Pseudocoelomates
The body cavity of a coelomate animal (called a coelom) is located
within the mesoderm.
The mesentery holds the gut in place.
Digestive cavity
Coelom
Mesoderm
Earthworms are Coelomates
6. Segmentation• Many animals have segmented body parts. In some cases the parts
repeat over and over again, as with
earthworms. In other animals, the segments are modified, such as
with insects… they essentially have 3
segments…. the head, thorax and abdomen.
An Earthworm segmentation
7. Body PlansProtostomes or Dueterostomes?
Embryonic Development
• During early development, the fertilized egg divides, or cleavages, to produce a solid ball of cells. Then, cell
migration results in a hollow ball called a blastula.
Embryonic Development Gastrulation – the development of the Germ Layers
• Some cells of the blastula migrate inward producing a gastrula. The opening is the blastopore. The internal
cavity is called the archenteron.
archenteron
Embryonic Development
• The Gastrula will become the gut (digestive tract) of the mature animal. In species that have a separate mouth and
anus, the tube will eventually extend through the length of the embryo and fuse with the opposite side. One opening will
become the mouth, the other will become the anus.
( Blastopore becomes the anus)( Blastopore becomes the mouth)
BlastoporeBlastopore
6 Major Trends in Evolution1.1. multicellularity multicellularity
2. development of tissues, first none (sponges), then 2 (cnidarians), 2. development of tissues, first none (sponges), then 2 (cnidarians), then 3then 3
3. development of symmetry, first none (sponges), then radial 3. development of symmetry, first none (sponges), then radial (cnidarians), then bilateral (cnidarians), then bilateral
4. development of a GVC(gut), first none (sponges), then sac-like 4. development of a GVC(gut), first none (sponges), then sac-like (cnidarians, flatworms), then complete (cnidarians, flatworms), then complete
5. development of a body cavity, first none (flatworms), then a 5. development of a body cavity, first none (flatworms), then a pseudocoelom (roundworms), then a coelom pseudocoelom (roundworms), then a coelom
6. development of segmentation; segmentation evolved in 6. development of segmentation; segmentation evolved in protostomes (annelids and arthropods) independently of that protostomes (annelids and arthropods) independently of that
which evolved in deuterostomeswhich evolved in deuterostomes. .
Evolution of SymmetryEvolution of Symmetry
• The evolutionary sequence
progressed from asymmetrical
animals to radial and then to bilaterally
symmetrical animals.
Summary of Evolutionary Trends
Symmetry
Asymmetry Radial Bilateral
Gut
No Gut Saclike Complete
Coelom
Acoelomate Pseudocoelomate Coelomate
Embryonic Germ LayersNone 2, (tissues, no organs) 3, (tissues and organs)
Evolutionary TrendsPhylum Tissue
ComplexityGerm
Layers
Body
Symmetry
Gut
OpeningsCoelom Embryonic
Development
Porifera parazoa - asymmetry 0 - -Cnidaria eumetazoa 2 Radial
symmetry
1 - -Platyhelminthes eumetazoa 3 Bilateral
Symmetry1 acoelomate -
Nematoda eumetazoa 3 Bilateral Symmetry
2 pseudo-
coelomate -Rotifera eumetazoa 3 Bilateral
Symmetry2 pseudo-
coelomate -Mollusca eumetazoa 3 Bilateral
Symmetry2 coelomate protostome
Annelida eumetazoa 3 Bilateral Symmetry
2 coelomate protostome
Arthropoda eumetazoa 3 Bilateral Symmetry
2 coelomate protostome
Echinodermata eumetazoa 3 Radial
Symmetry
2 coelomate deuterostome
Chordata eumetazoa 3 Bilateral Symmetry
2 coelomate deuterostome
(sponges)
(jellyfish, hydra)
(flatworms)
(roundworms)
(rotifers)
(clams, snails)
(earthworms)
(insects, spiders)
(starfish, sea urchins)
(common name)
Classification of the Kingdom AnimaliaProtozoans
Asymmetry Radial Symmetry Protostomes Deuterostomes* No Body Plan •Body Radiates from
a Central Point•Mouth forms at the
Blastopore•Anus forms at the
Blastopore
Evolutionary Trend
Simple Complex
An increase in “Cell Specialization” and “Division of Labor”
1. Phylum Porifera
(Sponges)2. Phylum Cnidaria
(Jellyfish, Sea Anemone)
Bilateral Symmetry
Body Plan Includes
Anterior and Posterior Ends
Dorsal and Ventral Surfaces
“Right” and “Left” sides are mirror images
Radial Symmetry Bilateral Symmetry
CoelomatesPseudocoelomates
CoelomatesCoelomates
Acoelomates
3. Phylum Platyhelminthes
(Flatworms)
4. Phylum Nematoda
(Roundworms)
8. Phylum Arthropoda
(Insects, Spiders)
7. Phylum Mollusca
(Snails, Clams)
6. Phylum Annelida
(Segmented Worms)
9. Phylum Echinodermata
(Starfish, Sea Urchins)
10. Phylum Chordata
*Class Ichthyes
*Class Amphibia
*Class Reptilia
*Class Aves
*Class Mammalia
Phyla 1-9 are Invertebrates “Animals without backbones”
Coelom: body cavity found between two layers of mesoderm.
5. Phylum Rotifera
(Rotifers)
Kingdom Animalia Survey
1. Phylum Porifera(Sponges)
Phylum Porifera(Sponges)
(exit for water)
(digest and distribute food)
(skeleton)
Choanaocyte
*** Sponges are Parazoans: they contain NO true tissues
*** Sponges are filter feeders
2. Phylum Cnidaria
Jellyfish, Corals, and other Stingers
General Characteristics
• Simple body plan-bag shaped organism• Radially symmetrical organization
• Consists of a mouth and a sac-like cavity• Lacks an anus
• The mouth is surrounded by a ring of tentacles• The cavity in the center of the gut, called the
gastrovascular cavity.
Two Body Forms
• Polyps
- attached to a surface
- ex: sea anemones
- mouth points up
• Medusae
- free floating
-ex: jellyfish
-mouth points down
The Tissue Layers
Inner tissue layer (endoderm): gastrodermisOuter tissue layer (ectoderm): epidermis
-contains cnidocysts, the stinging cellsMiddle layer (lacks a mesoderm): mesoglea (jelly-like substance)
3. Phylum Platyhelminthes(Flatworms)
• Platyhelminthes consists of three kinds of acoelomate flatworms.
• 1. Free-living Flatworms: such as planarians, which are carnivorous scavengers.
• 2. Flukes: are internal, or external, parasites that suck tissue fluids or blood.
• 3. Tapeworms: internal parasites that live in the intestinal tracts of vertebrates.
Planaria
Tapeworm Scolex (head) Young
Proglottids
Old
Proglottids
** tapeworms appear to be segmented, but they are not true “segmented” worms
4. Phylum Nematoda(Roundworms)
• Found in fresh water, marine, moist soil, tissues of plants, and tissues and body fluids of animals
• A complete digestive tract is present and nutrients are
transported through the body in the pseudocoelomic fluid.
• Free-living forms are important in decomposition • Animal parasitic forms can be hazardous to health.
(Trichinella spiralis in humans via undercooked infected pork)
Nematode
5. Phylum Rotifera(Rotifers)
• Rotifers are small, mainly freshwater
organisms, although some are marine and others are found in
damp soil.• Complete digestive
system is present.• Rotifer refers to the
crown of cilia that draws a vortex of water
into the mouth.
Rotifer
6. Phylum Mollusca(snails, bivalves (such as clams….have a shell which has two parts), octopuses and squids)
• In Squids, the shell is reduced and is
internal.• In octopuses, the
shell is entirely absent.
• Octopuses have a highly developed
nervous system with a large, complex
brain.
Snails
7. Phylum Annelid(Segmented Worms: includes leeches,
earthworms and polychaetes)
Earthworms ingest soil, extract nutrients in the digestive system and deposit undigested material (mixed with mucus from the digestive tract) as casts through the anus. Important to farmers as they till the soil and castings improve soil texture.
Phylum Annelid(Segmented Worms: includes leeches,
earthworms and polychaetes)
Fanworm
Polychaete Worm
8. Phylum Arthropoda(spiders, insects, crustaceans, and various related organisms)
• Arthropods have two kinds of life cycles…(1) complete metamorphosis, (2) incomplete
metamorphosis.
• Arthropods have: * jointed appendages, * a well-developed nervous system, *
specialized body segments, and * an exoskeleton made of chiton.
The specialized body segments are the: Head, Thorax and Abdomen
Incomplete Metamorphosis (immature forms are often called nymphs)
Nymphs resemble the adult in form except for being smaller and lacking fully developed wings and sexual organs.
Life Cycle: Egg nymph adult
Complete metamorphosisImmature forms are called larvae (larva, singular).
The pupal stage is a transition stage, when the larva is transformed to the adult. Pupa molts to the adult form.
Life Cycle: Egg --> larva --> pupa --> adult
9. Phylum Echinodermata(sea stars (starfish), sea urchins and sand dollars)
Echinoderms are Coelomates, Deuterostomes
Echinoderms have complete digestive systems
Although some adults exhibit radial symmetry,
Some features are bilateral, as are
the body shape of their larvae.
10. Phylum Chordata
• The Phylum Chordata consists of animals that exhibit the following
four features. In many cases, these features are temporary, appearing
only during embryonic development.
1. A Notochord
• A notochord provides support for
the body. It is a flexible cord located
on the dorsal surface. In most
cases, the notochord is
replaced by bone during development.
Notochord
2. A Dorsal Nerve Cord
• A dorsal nerve cord forms the basis of
the nervous system. In some chordates,
the nerve cord becomes the brain and spinal cord.
3. Pharyngeal Gill Slits• Pharyngeal Gill Slits provides channels
across the pharynx to the outside of the body. In some chordates, the slits become gills for oxygen exchange, or for filter feeding, while
in others, the slits disappear during embryonic development.
4. A Muscular Tail
• A muscular tail extends beyond the digestive system. In many chordates, such as humans, the tail is lost during
embryonic development.