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Chapter 32-34: Animals
Domain Eukarya
Domain
Eubacteria
AP Biology
Domain
Archaea
Domain
Eukarya
2007-2008
Common ancestor
Animal Characteristics
 Heterotrophs

must ingest others for nutrients
 Multicellular

complex bodies
 No cell walls

allows active movement
 Sexual reproduction
no alternation of generations
 no haploid gametophyte

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Animal Evolution
Cnidaria
Porifera
sponges
jellyfish
Nematoda
Platyhelminthes
Annelida
Mollusca
Echinodermata
Arthropoda
flatworms roundworms mollusks segmented
worms
redundancy,
segmentation
specialization,  mobility
insects
spiders
starfish
Chordata
vertebrates
 body & brain
backbone
size,  mobility
 body size endoskeleton
coelom  digestive sys
radial
body cavity  body complexity
 digestive & repro sys
bilateral symmetry
tissues
multicellularity
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Ancestral Protist
distinct body plan; cephalization
specialized structure & function,
muscle & nerve tissue
specialization &  body complexity
bilateral
Body Cavity
 Space for organ
system development

increase digestive &
reproductive systems
 increase food
capacity & digestion
 increase gamete
production
 Coelem


mesoderm &
endoderm interact
during development
allows complex
structures to develop
in digestive system
 ex. stomach
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acoelomate
ectoderm
mesoderm
endoderm
pseudocoelomate
ectoderm
mesoderm
endoderm
pseudocoel
coelomate
ectoderm
mesoderm
coelom cavity
endoderm
protostome vs. deuterostome
Invertebrate: Porifera
 Sponges

no distinct tissues or organs
 do have specialized cells
no symmetry
 sessile (as adults)

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food taken into each
cell by endocytosis
Invertebrate: Cnidaria
 Jellyfish, hydra, sea anemone, coral
tissues, but no organs
polyp
 two cell layers
 radial symmetry
 predators

 tentacles surround
gut opening
 extracellular
digestion
 release enzymes
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into gut cavity
 absorption by cells
lining gut
medusa
Stinging cells of Cnidarians
mouth
tentacles
sensory
cell
stinging
cell
hydra
trigger
stinging cell
with nematocyst
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discharged
nematocyst
undischarged
nematocyst
Invertebrate: Platyhelminthes
 Flatworms



tapeworm, planaria
mostly parasitic
bilaterally symmetrical
 have right & left & then have
head (anterior) end & posterior end
Animals now
 cephalization = development of brain
face the world
 concentration of sense organs in head
head on!
 increase specialization in body plan
ectoderm
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acoelomate
mesoderm
endoderm
Invertebrate: Nematoda
 Roundworms


bilaterally symmetrical
body cavity
C. elegans
 pseudocoelom = simple body cavity
 digestive system
 tube running through length of body (mouth to anus)

many are parasitic
 hookworm
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Invertebrate: Mollusca
 Mollusks




slugs, snails, clams, squid
bilaterally symmetrical (with exceptions)
soft bodies, mostly protected by hard shells
true coelem
 increases complexity & specialization of internal organs
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Invertebrate: Annelida
 Segmented worms


earthworms, leeches
segments
 increase mobility
 redundancy in body sections


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bilaterally symmetrical
true coelem
fan worm
leech
Invertebrate: Arthropoda
 Spiders, insects, crustaceans



most successful animal phylum
bilaterally symmetrical
segmented
 specialized segments
 allows jointed appendages

exoskeleton
 chitin (carbohydrate)
+ protein
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Arthropod groups
arachnids
8 legs, 2 body parts
spiders, ticks, scorpions
crustaceans
gills, 2 pairs antennae
crab, lobster, barnacles,
shrimp
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insects
6 legs, 3 body parts
Invertebrate: Echinodermata
 Starfish, sea urchins, sea cucumber



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radially symmetrical as adults
spiny endoskeleton
loss of bilateral symmetry?
deuterostome
Invertebrate quick check…
Invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda,
Annelida, Mollusca, Arthropoda, Echinodermata
 Which group includes snails, clams, and squid?
 Which group is the sponges?
 Which are the flatworms?
…segmented worms?
…roundworms?
 Which group has jointed appendages & an
exoskeleton?
 Which two groups have radial symmetry?
 What is the adaptive advantage of bilateral
symmetry?
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 Which group has no symmetry?
Chordata
 Vertebrates
fish, amphibians, reptiles, birds, mammals
hollow dorsal
nerve cord
 internal bony skeleton

 backbone encasing
vertebrate embryo
becomes brain
& spinal cord
spinal column
 skull-encased brain

deuterostome
Oh, look…
your first
baby picture!
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becomes gills or
Eustachian tube
pharyngeal
pouches
postanal
becomes tail tail
or tailbone
becomes
vertebrae
notochord
450 mya
salmon, trout, sharks
Vertebrates: Fish
 Characteristics

gills
body structure
 bony & cartilaginous skeleton
 jaws & paired appendages (fins)
 scales

body function
 gills for gas exchange
 two-chambered heart;
single loop blood circulation
 ectotherms

reproduction
 external fertilization
 external development in
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aquatic egg
body
Transition to Land
Evolution of tetrapods
Humerus
Femur
Pelvis
Tibia
Ulna
Shoulder
Radius
Lobe-finned fish
Fibula
Pelvis
Femur
Humerus
Tibia
Fibula
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Early amphibian
Ulna
Shoulder
Radius
Tiktaalik
350 mya
frogs
salamanders
toads
lungs
Vertebrates: Amphibian
 Characteristics

lung
body structure
 legs (tetrapods)
 moist skin
 gas exchange

buccal
cavity
glottis
closed
body function
 lungs (positive pressure) &
diffusion through skin for gas exchange
 three-chambered heart;
veins from lungs back to heart
 ectotherms

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reproduction
 external fertilization
 external development in aquatic egg
 metamorphosis (tadpole to adult)
heart
body
250 mya
Vertebrates: Reptiles
 Characteristics

body structure
dinosaurs, turtles
lizards, snakes
alligators, crocodile
lungs
 dry skin, scales, armor

body function





lungs for gas exchange
heart
thoracic breathing; negative pressure
three-chambered heart
ectotherms
reproduction
leathery embryo
shell
amnion
 internal fertilization
 external development in
amniotic egg
chorion
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body
allantois
yolk sac
150 mya
finches, hawk
ostrich, turkey
lungs
Vertebrates: Birds (Aves)
 Characteristics

body structure
 feathers & wings
 thin, hollow bone;
heart
heart
flight skeleton

body function
 very efficient lungs & air sacs
 four-chambered heart
 endotherms

reproduction
 internal fertilization
 external development in
amniotic egg
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body
trachea
lung
anterior
air sacs
posterior
air sacs
220 mya / 65 mya
Vertebrates: Mammals
 Characteristics

body structure
 hair
 specialized teeth muscles

body function
reproduction
 internal fertilization
 internal development in uterus
 nourishment through placenta
 birth live young
 mammary glands make milk
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heart
heart
contract
 lungs, diaphragm; negative pressure
 four-chambered heart
diaphragm
 endotherms
contracts

mice, ferret
elephants, bats
whales, humans
lungs
body
Vertebrates: Mammals
 Sub-groups

monotremes
 egg-laying mammals
 lack placenta & true nipples
 duckbilled platypus, echidna

marsupials
 pouched mammals
 offspring feed from nipples in pouch
 short-lived placenta
 koala, kangaroo, opossum

placental
 true placenta
 nutrient & waste filter
 shrews, bats, whales, humans
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Vertebrate quick check…





Which vertebrates lay eggs with shells?
Which vertebrates are covered with scales?
What adaptations do birds have for flying?
What kind of symmetry do all vertebrates have?
Which vertebrates are ectothermic and which
are endothermic
 Why must amphibians live near water?
 What reproductive adaptations made mammals
very successful?
 What characteristics distinguish the 3 subgroups of mammals?
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That’s
the buzz!
Any
Questions?
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