1. Fig. 18-0a
Animal diversity

2. Colonial protists as ancestors of modern animals
Fig. 18-2a
Colonial protists as ancestors of modern animals
Somatic
cells
Digestive
cavity
Reproductive cells 1
Colonial protist,
an aggregate
of identical cells 2
Hollow sphere
of unspecial-
ized cells 3
Beginning of cell
specialization 4
Infolding 5
Gastrula-like
“proto-animal”

3. What makes an animal an animal? Internal digestion
Fig. 18-5d
What makes an animal an animal? Internal digestion
Most sponges have no symmetry, but the Choanocyte shown here has radial symmetry

4. Evolution of multicellularity leading to the animal kingdom
Choanoflagellate colonies Sponge coanocytes Single choanoflagellate
Recent studies suggest that choanoflagellates are cousins to all animals in the same way that chimpanzees are cousins to humans. From left, a choanoflagellate colony, feeding cells (coanocytes) of sponges that resemble choanoflagellates and a choanoflagellate with its long flagellum and collar of filaments. There can be millions of choanoflagellates in a gallon of sea water. (Sean Carroll, New York Times, 12/13/2010)

5. Digestive tract and body cavity (coelom)
Fig. 18-3b
Digestive tract and body cavity (coelom)
Body covering
(from ectoderm)
Coelom
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
Digestive tract
(from endoderm)
Complete gut

6. Symmetry – radial and bilateral
Fig. 18-3a
Symmetry – radial and bilateral
Top
Dorsal surface
Anterior
end
Posterior
end
Ventral surface
Bottom

7. Body plans of animals helps reconstruct animal evolution
Fig. 18-4
No true
tissues
Sponges
Radial
symmetry
Cnidarians
Ancestral
colonial
protist
Echinoderms
Deuterostomes
Chordates (humans)
Eumetazoans
True
tissues
Flatworms
Bilaterians
Bilateral
symmetry
Molluscs
Protostomes
Annelids
Body plans of animals helps reconstruct animal evolution
Arthropods
Nematodes

8. Fig. 18-1b-1
Sperm
Egg 1
Meiosis
Key
Haploid (n)
Diploid (2n)
Adult

9. Sperm Egg Zygote (fertilized egg) Adult Fig. 18-1b-2 Meiosis Key
Haploid (n)
Diploid (2n)
Adult

10. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Fig. 18-1b-32 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult

11. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Blastula
Fig. 18-1b-4
Sperm
Egg 2 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult 4
Blastula
(cross
section)

12. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Blastula
Fig. 18-1b-5
Sperm
Egg 2 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult 4
Blastula
(cross
section) 5
Early gastrula
(cross section)

13. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Blastula
Fig. 18-1b-6
Sperm
Egg 2 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult 4
Blastula
(cross
section)
Ectoderm 5
Early gastrula
(cross section)
Endoderm 6
Internal sac
Future mesoderm
Later gastrula
(cross section)

14. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Blastula
Fig. 18-1b-7
Sperm
Egg 2 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult 4
Blastula
(cross
section)
Digestive
tract
Ectoderm 5
Larva 7
Early gastrula
(cross section)
Endoderm 6
Internal sac
Future mesoderm
Later gastrula
(cross section)

15. Sperm Egg Zygote (fertilized egg) Eight-cell Adult stage Blastula
Fig. 18-1b-8
Sperm
Egg 2 1
Meiosis
Zygote
(fertilized
egg) 3
Key
Haploid (n)
Diploid (2n)
Eight-cell
stage
Adult 8
Metamorphosis 4
Blastula
(cross
section)
Digestive
tract
Ectoderm 5
Larva 7
Early gastrula
(cross section)
Endoderm 6
Internal sac
Future mesoderm
Later gastrula
(cross section)

16. Lungs or lung derivatives
Fig. 19-1
Tunicates
Chordates
Ancestral
chordate
Lancelets
Hagfishes
Brain
Craniates
Lampreys
Head
Vertebrates
Sharks, rays
Vertebral column
Ray-finned fishes
Jawed vertebrates
Jaws
Lobe-fins
Lungs or lung derivatives
Amphibians
Lobed fins
Tetrapods
Reptiles
Legs
Amniotes
Amniotic egg
Mammals
Milk

17. Tetrapod evolution from the fossile record
Fig. 19-4ab
Devonian
Carboniferous
Eusthenopteron
Pandericthys
Tiktaalik
Tetrapod evolution from the fossile record
Acanthostega
Ichthyostega
Tetrapod with no gills,
limbs better-adapted
for bearing weight
Time known
to exist
420
400
380
360
340
320
300
280
260
Millions of years ago

18. Devonian Carboniferous Modern amphibians Time known to exist 420 400
Fig. 19-4ac
Devonian
Carboniferous
Modern
amphibians
Time known
to exist
Reptiles (including birds) and mammals
420
400
380
360
340
320
300
280
260
Millions of years ago

19. Fig. 19-6c

20. Wing claw (like dinosaur) Teeth (like dinosaur) Long tail with
Fig. 19-7a
Wing claw
(like dinosaur)
Teeth
(like dinosaur)
A bird is a feathered reptile able to fly
Long tail with
many vertebrae
(like dinosaur)
Feathers