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Invertebrates
Section Outline
Section 29-1

29–1 Invertebrate
Evolution
A.Origin of the Invertebrates
1.The First Multicellular
Animals
2.Beginnings of
Invertebrate Diversity
B.Invertebrate Phylogeny
C.Evolutionary Trends
1.
Specialized Cells, Tissues, and Organs
2.
Body Symmetry
3.
Cephalization
4.
Segmentation
5.
Coelom Formation
6.
Embryological Development
Section 29-1
Compare/Contrast
Comparing Invertebrates
Major
Characteristics Sponges
Cnidarians
Flatworms
Roundworms
Germ Layers
Absent
Two
Three
Three
Body
Symmetry
Absent
Radial
Bilateral
Bilateral
Cephalization
Absent
Absent
Present
Present
Coelom
Absent
Absent
Absent
Pseudocoelom
Early
Development
—
—
Protostome
Protostome
Pg. 748-749
Section 29-1
Compare/Contrast
Comparing Invertebrates
Major
Characteristics Annelids
Mollusks
Arthropods
Echinoderms
Germ Layers
Three
Three
Three
Three
Body
Symmetry
Bilateral
Bilateral
Bilateral
Radial (adults)
Cephalization
Present
Present
Present
Absent (adults)
Coelom
True coelom
True coelom
True coelom
True coelom
Early
Development
Protostome
Protostome
Protostome
Deuterostome
Invertebrate
Cladogram
Section 29-1
Echinoderms Chordates
Arthropods
Annelids
Mollusks
Radial
Symmetry
Roundworms
Flatworms
Pseudocoelom
Cnidarians
Radial
Symmetry
Protostome Development
Three Germ Layers;
Bilateral Symmetry
Sponges
Deuterostome
Development
Coelom
Tissues
Multicellularity
Single-celled
ancestor
Pg. 747
Section 29-2
29–2
Section Outline
Form and Function in Invertebrates
A. Feeding and Digestion
1. Intracellular and Extracellular
Digestion
2. Patterns of Extracellular Digestion
B. Respiration
1. Aquatic Invertebrates
2. Terrestrial Invertebrates
C. Circulation
1. Open Circulatory Systems
2. Closed Circulatory Systems
D. Excretion
1. Aquatic Invertebrates
2. Terrestrial Invertebrates
E. Response
1. Centralization and Cephalization
2. Specialization
F. Movement and Support
1. Hydrostatic Skeletons
2. Exoskeletons
3. Endoskeletons
G. Sexual and Asexual Reproduction
Section 29-2
Type of
Skeleton
Types of Invertebrate
Skeletons
Sponges
Hydrostatic
X
Exoskeleton
Endoskeleton
Cnidarians
Simple
(spicules or
spongin)
Flatworms
X
Roundworms
X
Types of Invertebrate Skeletons
Section 29-2
continued
Type of
Skeleton
Hydrostatic
Exoskeleton
Endoskeleton
Annelids
X
Mollusks
Arthropods
Echinoderms
Some
Some
(shells)
X
X
Section 29-2
Invertebrate Digestive Systems
Intestine
Gizzard
Crop
Mouth/anus
Pharynx
Mouth
Gastrovascular
cavity
Annelid
Anus
Gastrovascular
cavity
Cnidarian
Pharynx
Crop
Arthropod
Anus
Pharynx
Mouth
Mouth/anus
Flatworm
Stomach
and
digestive glands
Rectum
Intestine
Section 29-2
Invertebrate Respiratory Systems
Gill
Tracheal
tubes
Siphons
Movement of water
Insect
Mollusk
Airflow
Book
lung
Spider
Spiracles
Section 29-2
Invertebrate Circulatory Systems
Heartlike structure
Hearts
Small vessels in tissues
Heart
Blood
vessels
Sinuses
and organs
Heartlike
structures
Insect:
Open Circulatory System
Annelid:
Closed Circulatory System
Blood
vessels
Invertebrate
Excretory
Systems
Section 29-2
Flame
cells
Flatworm
Excretory
tubules
Nephrostome
Excretory pore
Flame cell
Excretory tubule
Nephridia
Digestive tract
Annelid
Arthropod
Malpighian
tubules
Section 29-2
Invertebrate Nervous Systems
Arthropod
Brain
Ganglia
Ganglia
Brain
Nerve
Cells
Flatworm
Cnidarian
Mollusk
Video
Circulatory Systems
Sponges &
Cnidarians
Worms & Mollusks
Arthropods &
Echinoderms
Characteristics of Animal
Kingdom
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Heterotrophs
Mobile
Multicellular
Lacks cell walls
Sexual reproduction
Body symmetry


Radial (radiate outward
from center)
Bilateral (two sides)


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
Dorsal = top side
Ventral = belly (bottom)
side
Anterior = front end
Posterior = rear end
 Asymmetrical (no plane
dividing body into equal
halves)
Which Type of Symmetry?
A
B
B
E
C
F
F
C
D
G
Development & Body Cavities




Zygote (fertilized egg)  blastula (hollow
ball) gastrula (inward folding creating
layers)
Ectoderm
Endoderm
Mesoderm
Germ Layers form embryonic layers.



Endoderm: inner layer  digestive
tract and respiratory system
Mesoderm: middle layer  muscles,
circulatory, reproductive and excretory
organs
Ectoderm: outermost layer  sense
organs, nerves, and epidermis
Body plans
Body plans
No body cavity
Fluid filled body cavity fully lined with mesoderm
Fluid filled body cavity partially lined with mesoderm
Protostomes vs Deuterostomes
Phylum Porifera, the sponges
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Asymmetrical
Lacks tissues =
cells
embedded in
matrix
Sessile
adults
sponges
Phylum Cnidaria

Examples:
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
jellyfish, coral, hydra,
sea anemones,
man-o-war
Radial symmetry
True tissues
2 cell layers

endoderm, ectoderm
Polyp (tubular body) &
Medusa (bell-shaped body)
Feeding

Body tissue surrounds
gastrovascular cavity, a single
opening space, where digestion takes
place.
Phylum Platyhelminthes,
the flatworms
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Examples:

planarians, flukes, tapeworms
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Acoelomates (no cavity)
Organs & systems
Three germ layers
Bilateral symmetry
Cephalization
(concentration
of nervous
tissue in head)
Flatworms
Planeria
Intermediate hosts
•Tapeworm larvae burrow into cow or
fish muscle tissue, which infects the
animal that eats this tissue.
Rat tapeworm
Parasites have a complex life history with several hosts
Human tapeworm
•Scolex: head with
suckers or hooks
Parasitic tapeworm from a fish
Tapeworm
Phylum Nematoda,
the roundworms

Examples =

heartworms,
hookworms,
pin worms
Roundworm Anatomy
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Pseudocoelom
false body cavity
between endoderm
& mesoderm
2 body openings
(mouth and anus)
Guinea worm disease
Preventive Measures
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Health education and low-technology measures to promote behavioral
change are used to prevent Guinea worm disease.
The most effective way to prevent it is to filter the tiny water fleas out
of drinking water. The Carter Center provides families with fine-mesh
filter cloths that fit over clay pots used to hold water.
Some people, especially nomadic groups, receive pipe filters, which are
small straw-like personal filters that can be worn around the
neck. These simple but revolutionary devices enable people to drink
water safely no matter where they are.
http://www.cartercenter.org/news/multimedia/media_console/console.aspx?sectionID=H&directoryEXT
=h07&linkEXT=CC_video.swf
Pinworm infection in child’s
intestine
Roundworms
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A report by the Centers for
Disease Control and Prevention
found that about 14 percent of
Americans are infected with
Toxocara – a parasite commonly
known as the round worm.
The disease is zoonotic – which
means you can get it from your
pet. The CDC says the parasite is
most commonly found in children
from low socioeconomic areas.
For the most part there aren't
any symptoms. But in rare cases
it can cause blindness, especially
in children.
Researchers say the worms are
transferred through cat and dog
fecal matter – in yards and sand
boxes – places where children
often play.
Filarial worms
•Primary cause of
elephantiasis
condition where
parts of the body
are swollen
•Requires arthropod
intermediate host to
complete life cycle
Filarial worms
Elephantiasis is a
condition of extreme
edema that occurs when
lymph vessels become
blocked by filarial worms.
Here the left leg is swollen
with the fluids accumulated
in the tissues as a result of
the blockage.
Phylum Annelida
Examples:
leeches, earthworms & marine worms
Segmented worms
 Separated by septa = dividing walls
 Bilateral symmetry
 Coelomates
 3 cell layers
 Advanced
organ systems
Annelids
Leeches release a
chemical that prevents the
prey from forming scabs.
A leech bite is less painful
than it is just messy with
the profuse bleeding.
Phylum Mollusca
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Coelomates=
true body cavity
(between
mesoderm)
Soft body
Unsegmented
2nd most successful
land animal
(after
insects)
Mollusks
Mollusk Anatomy

3 body parts:
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Visceral mass = houses
body organs
Mantle = heavy fold of tissue
surrounding visceral mass
Foot = ventral surface for
locomotion
Respiratory structure:

Gills = filamentous projections
that capture oxygen from the
water
Mollusk Groups
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Cephalopod =
“head-footed”
little or no shell
most advanced eye
Jet propulsion
Octopus, squid, nautilus
Cuttlefish
Mollusk Groups
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Bivalves =
“2 shells”
“hatchet-footed”
Clams, oysters, etc
Mollusk Groups
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Gastropods =
“belly-footed”
One shell
Snails, slugs, etc
Groups of mollusks

Gastropods: shell-less or singleshelled mollusks with muscular feet
Sea snail
Movement
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Snails: secrete
mucus and crawl
slowly
Cephalopods: fast
moving, drawing
water into mantle
cavity and forcing
water out of siphon
(like jet propulsion)
excessive amount of snail
mucus secreted
Snail Trail
Mexican turbo snail
Phylum Arthropoda

Jointed appendages

Segmented bodies

Exoskeleton

Largest phylum in
Animal Kingdom
Metamorphosis


Undergoes
morphological
changes during life
history
Incomplete = 3
stages
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Egg, nymph, adult
Complete = 4 stages

Egg, larva, pupa, adult
Arthropod Groups
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Arachnids =
spiders,
scorpions
Crustaceans =
lobsters,
shrimp
Insects =
grasshoppers,
butterflies, bees
Diplopoda =
millipedes
Chilopoda =
centipedes
Specialized appendages
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Mouthparts
Antennae
Legs
Pincers
Wings
Swimmerets
Phylum Echinodermata
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Spiny skinned
Radial symmetry
(as adults)
Endoskeleton
made
of
plates, ossicles
Water vascular
system for
moving & feeding
Regeneration
Water Vascular System,
for feeding & locomotion
Echinoderm groups
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Sea Stars
(starfish)
Sand dollars
& sea biscuits
Sea urchins
Echinoderm groups
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Sea cucumbers
Brittle stars
(serpent stars)
Sea lilies
Echindoerms
Subphylum Arachnida – black widow spider
Brown Recluse Spider
Scorpion
Wolf Spider
Subphylum Crustacea – hermit crab
Subphylum Crustacea –crab
Subphylum Crustacea – fire shrimp
Subphylum Insecta – lady bug
Subphylum Insecta – bee moth
The purple Sea urchin has sharp spines
to protect against predators.
A close-up of the mouth of a Green
Sea urchin, called Aristotles lantern.
Diversity of Echinoderms
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Sea cucumbers
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Sea lilies & feather stars
Red Prickly Sea Cucumber
Yum
Tasty!!!!!!!!
Sea Lilies