Transcript Zoology - Cardinal Newman

Kingdom Animalia
Zoology: The Study of Animals
Characteristics of the Animals
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 eukaryotic,
heterotrophs
Heterotrophs consume their organic
food. Heterotrophs are not capable of
making their own foods.
3. Animals are motile
Heterotrophy often requires motility to
acquire food. Animals have motility during
at least some part of their life cycle.
Motility is accomplished by a coordinated
effort of muscles and nerve cells.
4. Animal cells lack cell walls
Therefore a skeleton is necessary to
support the tissues of large animals.
5. Animals have a period of
embryonic development
• During embryonic development, cells
“Differentiate” and become specialized
leading to the “Division of Labor”.
Types of Animals
Animals are classified into 2 general groups
1.Invertebrates – animals which lack a
backbone or vertebral column… currently
grouped into 33 phyla.
2.Vertebrates - animals with a backbone or
vertebral column… all are found in
Phylum Chordata
Members of the Phylum
Chordata have 4 general
characteristics
1. A Dorsal, Hollow Nerve Cord
• A dorsal hollow
nerve cord forms
the basis of the
nervous system. In
some chordates, the
nerve cord becomes
the brain and spinal
cord.
2. A Notochord
A notochord is a
flexible cord located
on the dorsal surface.
In most cases, the
notochord is replaced
by bone during
development.
Notochord
3. A Muscular Tail
• A muscular tail extends beyond the
digestive system. In many chordates,
such as humans, the tail is lost during
embryonic development.
4. Pharyngeal Gill Slits (pouches)
• 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.
Evolutionary Trends
Simple organisms
Complex Organisms
An increase in “Cell Specialization” and “Division of Labor”
Classification of the Kingdom Animalia
Protozoans
Radial Symmetry
Asymmetry
•Body Radiates from
a Central Point
* No Body Plan
Protostomes
Deuterostomes
•Mouth forms at the
Blastopore
•Anus forms at the
Blastopore
Radial Symmetry
1. Phylum Porifera
(Sponges)
2. Phylum Cnidaria
Bilateral Symmetry
(Jellyfish, Sea Anemone)
Body Plan Includes
Anterior and Posterior Ends
Phyla 1-9 are Invertebrates
“Animals without backbones”
Bilateral Symmetry
Coelomates
Coelomates
9. Phylum Echinodermata 10. Phylum Chordata
(Starfish, Sea Urchins)
*Class Ichthyes
Dorsal and Ventral Surfaces
*Class Amphibia
“Right” and “Left” sides are
mirror images
*Class Reptilia
*Class Aves
*Class Mammalia
Acoelomates
Pseudocoelomates
Coelomates
6. Phylum Annelida
3. Phylum Platyhelminthes
4. Phylum Nematoda
(Segmented Worms)
(Flatworms)
(Roundworms)
7. Phylum Mollusca
5. Phylum Rotifera
(Snails, Clams)
Coelom: body cavity found between two
layers of mesoderm.
(Rotifers)
8. Phylum Arthropoda
(Insects, Spiders)
Animal Diversity
The key to the success of the Animal Kingdom
** Diversity is defined as the presence of a wide range of variations.
The Diversity of the Animals originates from the variations
that occur in their:
•
•
•
•
•
•
•
1. Tissue Complexity
2. Body Symmetry
3. Cephalization
4. GastroVascular Cavity (GVC)
5. Coelom
6. Segmentation, and
7. Protostomes and Deuterostomes.
1. Tissue Complexity
Eumetazoans are animals that are composed
of several types of have closely functioning
tissues.
Parazoans (sponges) are animals that are not
organized into true tissues and lack organs.
Embryonic Germ Layers
Tissues that become established during
early embryonic development are
called “germ layers”.
The three “germ layers” are the
ectoderm, mesoderm and endoderm.
Some organisms are diploblastic, their
embryos have two cell layers… hydra
and jellyfish….. they lack mesoderm.
Some organisms are triploblastic, their
embryos have three cell layers…the
ectoderm, mesoderm and endoderm
Embryonic Germ Layers
A blastula is a hollow
sphere of cells,
surrounding an inner
fluid-filled cavity called
the blastocoele.
Gastrulation occurs
when a blastula folds
inward and enlarges
to create a gastrula.
Embryonic Germ Layers
The ectoderm forms from the
outer layer of cells. It gives
rise to the skin and nervous
system.
The endoderm made of cells
that form the tube-like
structure in the gastrula.
These cells will form the lining
of the digestive system and
the majority of the respiratory
system.
The Mesoderm forms between
the ectoderm and endoderm. It
becomes the muscles,
connective tissues, skeleton,
kidneys, circulatory and
reproductive organs.
2. Body Symmetry
Body Shapes
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 radiates 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 and Posterior Ends
• Dorsal and Ventral Surfaces
• “Right” and “Left” sides are
mirror images
Evolution of Symmetry
Larval stage only
The evolutionary
sequence
progressed from
asymmetrical
animals to radial and
then to bilaterally
symmetrical animals.
3. Cephalization
The term “Cephalo” means “head”.
As animals with bilateral
symmetry evolved, there
was a greater increase in
nerve tissue (brain cells)
concentrated in the
anterior end (the
head)….this is called
“cephalization”.
As brains formed,
accessory organs for
seeing, hearing, tasting,
also formed.
4. Gastrovascular Cavity (GVC)
Gastro Vascular Cavities
(GVC) are areas where
food is digested.
If an animal has only one
digestive opening,
processing food is
limited….like in a jellyfish,
or flatworm
Animals with two digestive
openings, a designated
digestive tract, digest
food more thoroughly and
can exact more energy.
Gastrovascular
cavity
5. The Coelom: Body Cavity
The coelom is a body cavity which is lined
with mesoderm.
The cavity also enables the internal organs
to grow and move independently of the
outer body wall….. If it were not for your
coelom every beat of your heart would
ripple throughout your entire body.
Arrangement of
Ectoderm, Mesoderm, and Endoderm
An acoelomate animal does not have a body cavity.
Digestive cavity
(Gut)
Flatworms: Tapeworms
A pseudocoelomate animal has a body cavity
(called a pseudocoelom) located between
endoderm and mesoderm.
Digestive cavity
(Gut)
pseudocoelom
Roundworms
The body cavity of a coelomate
animal (called a coelom) is located
within the mesoderm.
The mesentery is a
membrane that holds
the gut in place.
Coelom
Digestive cavity
(Gut)
Mesoderm
Earthworms and You
6. Segmentation
Many animals have
segmented body parts.
In some cases the parts
repeat over and over
again, as with
earthworms.
An Earthworm segmentation
In other animals, the
segments are modified,
such as with insects…
insects essentially have
3 segments…. the head,
thorax and abdomen.
7. Body Plans:
Protostomes and Deuterostomes
Embryonic Development
• During early development, the fertilized egg
divides, or cleaves, to produce a solid ball
of cells.
Embryonic Development
Next, some of the cells of the blastula migrate
inward producing a gastrula. The opening is
called the blastopore.
The internal cavity is called the archenteron.
Gastrulation: The Development of Germ Layers
Archenteron
Archenteron
Blastopore
( Blastopore becomes the mouth)
Blastopore
( Blastopore becomes the anus)
Summary of Evolutionary Trends
Asymmetry
No GVC
Symmetry
Radial
GVC
Saclike GVC
Bilateral
Complete GVC
Coelom
Acoelomate Pseudocoelomate Coelomate
Embryonic Germ Layers
None
2, (tissues, no organs)
3, (tissues and organs)
Evolutionary Trends
Phylum
(common name)
Tissue
Complexity
Germ
Layers
Body
Symmetry
Gut
Openings
Coelom
Porifera
parazoa
-
asymmetry
0
eumetazoa
2
Radial
symmetry
1
-
-
(sponges)
Cnidaria
(jellyfish, hydra)
Embryonic
Development
Platyhelminthes
(flatworms)
eumetazoa
3
Bilateral
Symmetry
1
acoelomate
-
Nematoda
eumetazoa
3
Bilateral
Symmetry
2
pseudocoelomate
-
eumetazoa
3
Bilateral
Symmetry
2
pseudocoelomate
-
eumetazoa
3
Bilateral
Symmetry
2
coelomate
eumetazoa
3
Bilateral
Symmetry
2
coelomate
protostome
eumetazoa
3
Bilateral
Symmetry
2
coelomate
protostome
Echinodermata
eumetazoa
(starfish, sea urchins)
3
Radial
Symmetry
2
coelomate
deuterostome
eumetazoa
3
Bilateral
Symmetry
2
coelomate
deuterostome
(roundworms)
Rotifera
(rotifers)
Mollusca
(clams, snails)
Annelida
(earthworms)
Arthropoda
(insects, spiders)
Chordata
protostome
Kingdom Animalia Survey
1. Phylum Porifera
(Sponges)
Phylum Porifera
(Sponges)
(exit for water)
(skeleton)
(digest and
distribute food)
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
• Consists of a mouth and a sac-like cavity, no anus
• The mouth is surrounded by a ring of tentacles
• The cavity in its center is its gastrovascular cavity.
Two Body Forms
Polyps
- sessile
- ex: sea anemones
- mouth points up
Medusa
- free floating
- ex: jellyfish
- mouth points down
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)
Old Proglottids
Young Proglottids
** tapeworms appear to be segmented, but they are not true
“segmented” worms
4. Phylum Nematoda
(Roundworms)
* Mostly found in fresh water, marine, moist soil.
* A complete digestive tract.
* Free-living forms are important in decomposition
• Animal parasitic forms can be hazardous to health.
(Trichinella spiralis in humans via undercooked infected pork)
Nematoda
5. Phylum Rotifera
(Rotifers)
• Rotifers are small
organisms found in
damp soil.
• Complete digestive
system is present.
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)
Leeches are freshwater. Many are carnivorous and feed on
small invertebrates, while some attach temporarily to
animals to feed on blood.
Earthworms ingest soil, extract nutrients in the digestive
system and deposit undigested material through the anus.
Polychaetae drift and swim in the plankton, some crawl
along the sea floor, and many live in tubes they construct
by mixing sand and shell bits with mucus.
Tube-dwellers include the fanworms that feed by trapping
suspended food particles in their feathery filters which are
extended from the tubes.
Phylum Annelid
(Segmented Worms: includes leeches,
earthworms and polychaetes)
Polychaete Worm
Fanworm
Open vs. Closed Blood Systems
Annelids are considered to be very advanced in
the animal kingdom…. A closed blood system
is one of the reasons why.
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.
** Phylum Arthropoda is the largest and most complex Phylum
The specialized body segments are the: Head, Thorax and Abdomen
Arthropods must shed their exoskeletons in order to
grow…. The process is called molting.
Emerging Insect
Discarded Exoskeleton
Incomplete Metamorphosis (changing forms)
(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 metamorphosis
Immature 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
shapes 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.