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Survey of Animal Kingdom
Introduction; Porifera-Nematoda
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Characteristics of Animals
 Multi-celled,
heterotrophic, eukaryotes
 Require oxygen for aerobic respiration
 Reproduce sexually, and perhaps asexually
 Motile at some stage
 Develop from embryos
 Animal cells lack the rigid cell wall found in
plant cells.
Chordates
9 Major Phyla
of Animals
Porifera (sponges)
Cnidaria (jellyfish, corals, etc)
Platyhelminthes (flatworms)
Nematoda (roundworms)
Mollusca (mollusks)
Annelida (segmented worms)
Arthropoda (Bugs, crabs, etc)
Echinodermata (starfish, etc.)
Chordata (fish, tetrapods, etc.)
Echinoderms
Arthropods
Annelids
Coelomate
Ancestry
Mollusks
Rotifers
Roundworms
Bilateral
Ancestry
Radial
Ancestry
Multicelled
Ancestry
Flatworms
Cnidarians
Sponges
Single-celled, protistan-like ancestors
Overview of the Animal Kingdom
Another view of the A.K.
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
Protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
Animal Architecture
supra-phyletic features
(“above-the-phylum” features)
 LEVELS OF ORGANIZATION
 Animals range from simple to complex in their
organization.
• Cellular Level: (of organization) Sponges
• Tissue Level: Cnidaria
• Organ Level: Flatworms, Roundworms, Segmented
worms, Molluscs, Arthropods, Echinoderms,
Chordates
Animal Architecture
supra-phyletic features
EMBRYOLOGICAL ARCHITECTURE
 Diploblastic or Triploblastic?

2 germ layers or 3 germ layers
 Acoelomate,

No, false, or true… body cavity (coelom)
 Protostome


or Deuterostome?
Blastopore becomes mouth or it becomes anus.
Symmetry


Pseudocoelomate, Eucoelomate?
None, Radial, Bilateral
Segmentation
a Eggs form and mature in female
reproductive organs, and sperm
form and mature in male
reproductive organs.
b A sperm and an egg fuse at their
plasma membrane, then the nucleus
of one fuses with the nucleus of the
other to form the zygote.
c By a series of mitotic cell
divisions, different daughter cells
receive different regions of the egg
cytoplasm.
d Cell divisions, migrations, and
rearrangements produce two or
three primary tissues, the
forerunners of specialized tissues
and organs.
Gamete formation
Germ Layers
Fertilization
frog sperm
Cleavage
Gastrulation
midsectional views
e Subpopulations of cells are
sculpted into specialized organs
and tissues in prescribed spatial
patterns at prescribed times.
Organ Formation
top view
f Organs increase in size and
gradually assume specialized
functions.
side view
Growth, tissue
Specilazation
Fig. 43-4, p.758
Generalized
Embryological
Development
fertilization,
zygote
cleavage stages, 2, 4, 8, etc.
morula (solid ball of cells)
blastula (hollow ball of cells)

with blastocoel (central cavity)
gastrulation,
gastrula
archaenteron (gut)
formation of germ layers

•ectoderm
•endoderm
•mesoderm
A gastrula
Looks like this
this hole is the
blastopore
p.769
Embryonic Germ Layers and
the Tissues They Produce
 Ectoderm (“outer skin” the outer germ layer)


Skin,
Nervous system
 Endoderm

Lining of digestive syst.

Lining of lungs, etc
 Mesoderm



Cardiovascular
Bone
Muscle, etc
If an animal forms from an embryo of just 2 germ layers it is said to be diploblastic
If an animal forms from an embryo of 3 germ layers it is said to be triploblastic
Symmetry, radial or bilateral?
Fig. 25-5, p.406
Radial vs Bilateral Symmetry
The Gut
none, saclike, or tubular?
 Region
where food is digested and then
absorbed. It can be a…
 Saclike gut: (the digestive system has one opening)

One opening for taking in food and expelling
waste. e.g. Cnidaria, Platyhelminthes
 Tubular

gut: (the digestive system has two openings)
Opening at both ends; mouth and anus
e.g. Arthropoda, Chordata, Nematoda, Mollusca,
Echinodermata, Annelida.
The Body Cavity or Coelom
acoelomate, pseudocoelomate, eucoelomate
Segmentation
 Repeating
series of body units
 Units may or may not be similar to one
another
 Earthworms - segments appear similar
 Insects - segments may be fused and/or
have specialized functions
 Annelida, Arthropoda, Chordata
Segmentation
(it evolved more than once; it must work pretty well !)
sponges
cnidarians
flatworms
coelom lost
annelids mollusks roundworms
coelom
reduced
pseudocoel
arthropods
echinoderms
chordates
coelom
reduced
molting
radial ancestry, two
germ layers
true tissues
multicelled
body
PROTOSTOMES
mouth from
blastopore
DEUTEROSOMES
anus from blastopore
bilateral, coelomate ancestry,
three germ layers
Fig. 25-7, p.407
Segmentation arose early,
Ediacaran Fossils, 600-500 myp
Fig. 25-8a, p.407, Spriggina
Fig. 25-8b, p.407, Dickinsonia
Segmentation
an early trilobite
fire worm
Fig. 25-8c, p.407
Segmentation
Segmentation
Segmentation
Survey of the
Major Animal Phyla
Know these 9:
PORIFERA
CNIDARIA
PLATYHELMINTHES
NEMATODA
MOLLUSCA
ANNELIDA
ARTHROPODA
ECHINODERMATA
CHORDATA
Fig. 17-05
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
Protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
Animal Origins
 Originated
during the Precambrian
(1.2 billion - 670 million years ago)
 From
what? Two hypotheses:

Multinucleated ciliate became compartmentalized

Cells in a colonial flagellate became specialized
Animal
Origins
3. Choanocytes
1. Choanoflagellates
2. Proterospongia
Volvox, a colonial green alga
Animal
Origins
The peculiar flagellated collar cell is found in:
1. Choanoflagellates, single celled-Protists
2. Proterospongia, a colonial organism
3. Choanocytes of Sponges, a multi-celled animal
Fig. 25-4a, p.405
Animal
Origins
Choanoflagellates
a Unicellular Protist
Fig. 25-4b, p.405
Animal
Origins
Proterospongia
a colonial array of
choanoflagellates around a
central gelatinous matrix
Fig. 25-4c, p.405
p.408
Phylum Porifera
sponge1 sponge2
Widespread,
benthic, sessile
filter-feeders. w/ choanocytes !
Cellular level of organization
No symmetry
No tissues
No organs

all
aquatic, mostly marine, a few
live in freshwater.
Reproduce sexually (and asex)
Microscopic swimming larval
stage
Fig. 25-9a, p.408
Sponge Structure
Cellular Organization
can reproduce asexually by fragmentation
Usually Sexual Reproduction
Boring Sponge
Fig. 25-9b, p.408
Glass Sponge Skeleton
Tube Sponge
Fig. 25-9c, p.408
Phylum Cnidaria
mesogleafilled bell
”No head, no anus, no problem !”
tentacles
Radial
Symmetry
Tissue Level of Organization
Diploblastic
Mesoglea

Sac-like
Gut
Stinging cells (nematocysts)
Polyp and/or Medusa stages
Fig. 25-13b, p.410
Two Main Body Plans
POLYP stage usually asexual
MEDUSA stage is sexual
outer epithelium
(epidermis)
Polyp
mesoglea
(matrix)
Medusa
inner epithelium
(gastrodermis)
Fig. 25-12, p.410
Phylum Cnidaria
nematocysts
 Only
animals that
produce
nematocysts
capsule’s lid
at free surface
of epidermal
cell
trigger
barbed
thread
inside
capsule
nematocyst
Fig. 25-13, p.410
Cnidarian Diversity
3 main groups…
 Scyphozoans (“cup animals”)

(medusa is dominant stage, polyp is reduced)

True Jellyfish
 Anthozoans

(“flower animals”)
(polyp stage only, no medusa)


Sea anemones
Corals
 Hydrozoans (“water animals”)

(polyp is the dominant stage, medusa is reduced)



Hydroids
Fire Coral
Portugese man o’ war
Phylum Cnidaria: Coral Polyps
Obelia Life Cycle
(Hydrozoan)
reproductive
polyp
male medusa
female medusa
ovum
sperm
zygote
feeding
polyp
polyp
forming
planula
Fig. 25-15a, p.411
Reproduction in Hydra sp.
Feeding in
Hydra
Sea anemone feeding on fish youtube
Fig. 25-14a2, p.411
The Portugese man-o-war is a colonial hyrozoan.
The painful/deadly box jellies of Australia are hydroza too.
Fig. 25-14b, p.411
Flatworms:
Phylum Platyhelminthes
 Acoelomate,
bilateral, cephalized animals
 Organ
Level of Organization
All have simple or complex organ systems
 Most
are oviparous hermaphrodites
Flatworms are acoelomate,
bilateral and have a saclike gut
Planarian Organ Systems
Flatworms have much more sophisticated organ systems than
Cnidaria. Cnidaria are at the tissue level of organization while
flatworms are at organ level of organization.
Digestive
System
Nervous
System
Reproductive
System
Excretory System
Fig. 25-16, p.412
Four Major Groups

Turbellarians (Turbellaria)


Flukes (Trematoda)
•

E.g. Chinese Liver Fluke, etc.
Monogenea


E.g. the Planaria, etc.
Gyrodactylus
Gyrodactylus
Tapeworms (Cestoda)

E.g. Beef tapeworm, fish tapeworm, etc.
Fish tapeworm
Planaria
Chinese live fluke
Many flatworms are parasites
Shistosoma mansoni, the blood fluke
Tapeworms are in Phylum Platyhelminthes
Taenia saginata, the beef tapeworm
proglottids
a Larvae, each
with inverted
scolex of future
tapeworm,
become encysted
in intermediate
host tissues
(e.g., skeletal
muscle)
scolex
b A human, a definitive
host, eats infected,
undercooked beef which
is mainly skeletal muscle
d Inside each fertilized egg, an
embryonic, larval form develops. Cattle
may ingest embryonated eggs or ripe
proglottids, and so become intermediate
hosts
c Each sexually mature
proglottid has female
and male organs. Ripe
proglottids containing
fertilized eggs leave
host in feces, which may
contaminate water and
vegetation.
Fig. 25-18, p.413
Proglottids (look like
scolex
segments but aren’t)
Fig. 25-18e, p.413
Tapeworm
Reproductive unit
(proglottid)
with skin removed
Scolex
Suckers
and hooks
Figure 17.13ba
Roundworms (Nematoda)
Vinegar eels
C.elegans
Vinegar eels2
youtube3

False coelom (pseudocoelom)
 Complete digestive system
pharynx
intestine
false coelom
eggs in uterus
gonad
anus
muscularized body wall
Fig. 25-27, p.419
Nematoda have a pseudocoelom and have a tubular
digestive system with both mouth and anus
pseudocoelom
Many Nematodes are parasitic
but many are free-living too.
They are perhaps the most abundant animals on Earth.
A square meter of sediment or soil can contain millions.
elegans “C. elegans”
 Dirofilaria immitis dog heartworm
 Ascaris
 Anisakis “the sushi worm”
 Enterobius vermicularis “pinworms”
 Wuchereria bancrofti (elephantiasis)
 Caenorhabditis
The Nobel Prize in Physiology or
Medicine 2002

The Nobel Assembly at Karolinska Institutet has
awarded the Nobel Prize in Physiology or
Medicine jointly to Sydney Brenner, Robert
Horvitz and John Sulston for their discoveries
concerning "genetic regulation of organ
development and programmed cell death".By
using the nematode Caenorhabditis elegans as a
model system, the Laureates have identified key
genes regulating these processes. They have
also shown that corresponding genes exist in
higher species, including man.This year´s Nobel
Laureates have identified key genes regulating
organ development and programmed cell death
in the nematode C. elegans. They have also
shown that corresponding genes controlling
these processes exist in humans.
Dog Heart Worms
Larvae in blood transmitted by mosquitoes
Adults in pulmonary vessels and heart
Ascaris worms
Ascaris
Adult worms
live in the lumen of the small intestine. A female may produce approximately 200,000 eggs per day, which are
passed with the feces
. Unfertilized eggs may be ingested but are not infective. Fertile eggs embryonate and become
infective after 18 days to several weeks
, depending on the environmental conditions (optimum: moist, warm, shaded
soil). After infective eggs are swallowed
, the larvae hatch
, invade the intestinal mucosa, and are carried via the portal,
then systemic circulation to the lungs
. The larvae mature further in the lungs (10 to 14 days), penetrate the alveolar walls,
ascend the bronchial tree to the throat, and are swallowed
. Upon reaching the small intestine, they develop into adult
worms
. Between 2 and 3 months are required from ingestion of the infective eggs to oviposition by the adult female. Adult
worms can live 1 to 2 years.
The
Sushi Worm
Wuchereria bancrofti
“elephantiasis”
transmitted by mosquitoes
adults up to 2.5 inch
Fig. 25-28c, p.419
Pinworms