1. Chapter 19
Evolution of
Animals
Lecture Outline
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Animals have distinctive characteristics
 Animals are multicellular eukaryotes
 Heterotrophs – must acquire nutrients from an
external source
 Usually reproduce sexually
 Many animals have Muscles & Nerves
 Search actively for food
 Seek mates, shelter, suitable climate
19-2

3. 3 Types of Symmetry in Animals
 3 Types of symmetry
 Asymmetry – no particular body shape
 Sometimes sessile – attached to substrate
 Exs: sponges
 Radial – organized circularly
Exs: jellyfish, starfish
 Bilateral – right and left halves
 Cephalization – head region (brain)
 Exs: mammals, insects
19-3

4. Symmetry & Anatomical Terms
l posterior
dorsa
anterior l
tra
ven
radial symmetry bilateral symmetry
19-4

5. 19.4 Phylum Porifera: Sponges
 Sponges
 Only Animals without true tissues
 Asymmetrical body plan
 Body is perforated by pores
 Filter feeder
19-5

6. Figure 19.4 Sponge anatomy (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
osculum H2O out
spicule
pore
amoeboid cell
H2O in
through epidermal cell
pores
sponge wall amoeboid
collar nucleus cell
central
cavity
flagellum
Sponge organization collar cell (choanocyte) 19-6

7. 19.5 Phylum Cnidaria
 Phylum Cnidaria – most in the sea
 Radial symmetry. Polyp (mouth pointed up) & Medusa
(mouth pointed down) body forms
 Capture their prey with a ring of tentacles that have
specialized stinging cells, cnidocytes
 Incomplete digestive tract (one opening)
 Exs: jellyfish, sea anemone
19-7

8. Figure 19.5A Cnidarian diversity
19-8

9. Phylum: Platyhelminthes
 Phylum Platyhelminthes = Flatworms
 Bilateral symmetry
 Have 3 germ layers
 Ectoderm from which body wall develops
 Endoderm from which digestive cavity develops
 Mesoderm which contributes to organ formation
19-9

10.  Flatworm Ex.: Planarians
 Digestive System – incomplete (only 1 opening),
undigested food exits through pharynx (mouth is in
middle of body)
 Reproductive System – Hermaphrodites (both male
and female sex organs) and perform cross-fertilization
(when two flatworm mate, each is fertilized and
fertilizes the other)
19-10

11. Figure 19.6 Planarian anatomy (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
auricle eye spots
sense organs 5 mm
© Tom E. Adams/Peter Arnold/Photolibrary
19-11

12. 19.7 Some flatworms are parasitic
 Tapeworms
 Endoparasites (internal parasites) of various vertebrates
 Scolex (head region) bears hooks and suckers for attachment to
the intestinal wall of the host
 Flukes
 Endoparasites of various vertebrates
 Anterior end of the animal has an oral sucker and at least one
other sucker used for attachment to the host
19-12

13. Figure 19.7A Tapeworm (Taenia solium) anatomy and life cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
hooks
sucker scolex proglottid
Bladder worm attaches
to human intestine 250 μm 1.0 mm
where it matures into a
tapeworm. As the tapeworm grows, proglottids mature, and eventually fill with eggs.
(left): © James Webb/Phototake; (right): © John D. Cunningham/Visuals Unlimited
19-13

14. 19.8 Body Cavity = Coelom
 One defining characteristic in animals is the
presence or absence of a body cavity or coelom
 Flatworms do not have any body cavity
 Roundworms have a pseudocoelom
 Body cavity incompletely lined by mesoderm
 Mesoderm lines only the body wall
 Molluscs, annelids, arthropods, echinoderms and
chordates have a true coelom
 Body cavity completely lined by mesoderm
 Mesoderm lines both the body wall and the digestive tract
19-14

15. Figure 19.8 Body cavities
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
pseudocoelom endoderm mesoderm coelom mesentery mesoderm
endoderm mesoderm
digestive cavity ectoderm digestive cavity ectoderm endoderm digestive cavity ectoderm
Acoelomate (flatworms) Pseudocoelomate (roundworms) Coelomate (molluscs, annelids, arthropods,
echinoderms, chordates)
19-15

16. 19.9 Phylum Mollusca
 All Molluscs have a body composed of
 Foot – strong, muscular portion used for locomotion
 Visceral Mass – soft-bodied portion that contains
internal organs
 Mantle – covering that envelops the visceral mass
 May secrete an exoskeleton called a shell
 Rasping, tonguelike radula
 Bears many rows of teeth and is used to obtain food
 3 common groups
 Gastropods, cephalopods, and bivalves
19-16

17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
19.9 Molluscs have a
three-part body plan
eyes
 Gastropods
 Meaning
stomach-footed
foot
growth line spiral shell
Land snail  Includes snails
tentacle
gills  Animal moves
by muscle
contractions that
pass along its
foot
mantle ventrally flattened
foot
Three-stripedorisnudibranch
1 Gastropods
(nudibranch): © Kenneth W. Fink/Bruce Coleman, Inc 19-17
Figure 19.9B Three groups of molluscs

18. Figure 19.9B Three groups of molluscs (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
eye
arm
shell
tentacles
suckers
Two-spotted octopus
2 Cephalopods eye
Chambered nautilus
(nautilus): © Douglas Faulkner/Photo Researchers, Inc
 Cephalopods (meaning head-footed) including
octopuses, squids, and nautiluses
 Foot has evolved into tentacles about the head 19-18

19. Figure 19.9B Three groups of molluscs (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
eyes shell tentacles
on mantle
growth lines
of shell
Bay scallop
3 Bivalves
Blue mussel
(scallop): Courtesy Larry S. Roberts (mussel): © Fred Whitehead/Animals Animals;
 Bivalves (shells have two part) including clams,
oysters, scallops, and mussels
 Clam is a filter feeder and food particles and water
19-19
enter the mantle cavity by way of a siphon

20. 19.10 Phylum Annelida: Segmented worms
Segmentation can be seen externally by the rings that
encircle the body
 Complete digestive tract
Exs: Earthworms & Leeches
19-20

21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 19.10A
pharynx Earthworm
brain anatomy
mouth
esophagus
hearts (5pairs) coelom
crop
seminal vesicle
dorsal blood vessel
nephridium
ventral blood vessel
ventral nerve cord
anus
clitellum
19-21

22. Figure 19.10B Other annelids (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
anterior sucker
Posterior
sucker
c. Medicinal leech
© St. Bartholomews Hospital/SPL/Photo Researchers, Inc.
19-22

23. Phylum Nematoda: Roundworms
 Roundworms = Nematodes
 Nonsegmented
 Free-living and parasitic species
 Exs: Pinworms & Hookworms
19-23

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
cyst
© James Solliday/Biological Photo Service SEM 400x
Figure 19.11B
Figure 19.11A Ascaris
Encysted Trichinella larva.
19-24

25. Phylum: Arthropoda
 Extremely diverse – more than 1 million species
 Six characteristics
1.Jointed appendages
2.Exoskeleton
3.Segmentation
4.Well-developed nervous system
5.Adaptation of respiratory organs
6.Reduced competition through metamorphosis
19-25

26. Figure 19.12A Exoskeleton and jointed appendages of a crayfish
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
second walking leg
third walking leg
first walking leg
(pinching claw) fourth walking leg
fifth walking leg
uropods
swimmerets
antennule
compound
antenna eye mouth anus
gills telson
Cephalothorax Abdomen 19-26

27. Figure 19.12B Monarch butterfly metamorphosis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Caterpillar, eating stage Pupa, cocoon stage Metamorphosis occurs Emergence of adult Butterfly, adult stage
(all): © John Shaw/Tom Stack & Associates
19-27

28. 19.13 Arthropods are diverse
 Crustaceans
 Largely marine arthropods that include crabs,
barnacles, shrimps, and crayfish
 Head usually bears a pair of compound eyes and five
pairs of appendages
 Centipedes and millipedes
 Centipedes – pair of appendages on every segment
 Millipedes – 2 pairs of appendages on most segments
19-28

29. Figure 19.13A Crustacean diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
eye
mouth
legs (5 pairs)
Sally light foot crab 19-29
(crab): © Michael Lustbader/Photo Researchers, Inc

30. Figure 19.13B Centipede and millipede
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
antenna antenna
legs
legs
Centipede
Millipede
(centipede): © David M. Dennis/Animals Animals; (millipede): © Geof de Feu/Imagestate 19-30

31. 19.13 Arthropods are diverse
 Arachnids include spiders, scorpions, ticks,
mites, and harvestmen
 Spiders have four pairs of legs
 Scorpions are the oldest terrestrial arthropods
 Ticks and mites are parasites
19-31

32. Figure 19.13C A spider and two of its relatives
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
abdomen cephalothorax
telson
pedipalp
stinger
compound eye
Horseshoe crab
walking legs
Giant abdomen
scorpion
cephalothorax
Black widow spider
(scorpion): © Tom McHugh/Photo Researchers, Inc.; (horseshoe crab): © Jana R. Jirak/Visuals Unlimited; 19-32
(spider): © Ken Lucas

33. Figure 19.14 Insect diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Leathery forewings
antennae cover membranous
hindwings
chewing
mouthparts
Grasshopper
© Chris Mattison/Frank Lane Picture Agency/Corbis
19-33

34. Figure 19.14 Insect diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
scale-covered
wings
sucking
mouthparts
Butterfly
© McDonald Wildlife Photography/Animals Animals
19-34

35. 19.15 Phylum Echinodermata
Radial symmetry as adults
Move using a water vascular system (take in
water through sieve plate and pumping into tube
feet, when foot touches surface, center withdraws
and causes suction-alternate this to move)
Ex: Sea stars, Sea Urchins & Sand Dollars
19-35

36. Figure 19.15 Echinoderm structure and diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
stomach anus arm
sieve plate
endoskeletal plates
eyespot
skin gill
gonad
coelom
digestive
tube feet ampulla
gland
19-36

37. Figure 19.15 Echinoderm structure and diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
spines
Seaurchin 19-37
© Randy Morse/Animals Animals

38. Figure 19.15 Echinoderm structure and diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sand dollar
© Andrew J. Martinez/Photo Researchers, Inc.
19-38

39. 19.16 Phylum Chordata
Simple Chordates Exs: Lancelet & Tunicate
4 characteristics
1. Dorsal supporting rod (notochord)
2. Dorsal tubular nerve cord
3. Pharyngeal pouches (become gills, in humans become
part of the ear)
4. Postanal tail
19-39

40. Figure 19.17A The invertebrate chordates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.Tunicate b.Lancelet
a: © Heather Angel/Natural Visions; b: © Rick Harbo
19-40

41. Figure 19.17B Phylogenetic tree of the chordates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
mammary gland
common ancestor
amniotic egg Mammals
Amniotes
Tetrapods
limbs
Reptiles*
lungs
Gnathostomes
Amphibians
bony
Vertebrates
skeleton
Lobe-finned Fishes
jaws
Chordates
Ray-finned Fishes
vertebrae
Cartilaginous Fishes
Jawless Fishes
ancestral
chordate
Tunicates
Lancelets
* includes birds
19-41

42. 19.18 Jaws, a bony skeleton, and lungs
evolved among the fishes
 Jawless Fishes (Class Agnatha)
 Smooth, scaleless skin, no jaws or paired fins
 Cartilaginous Fishes (Class Chondrichthyes) sharks &
rays
 Skeletons of cartilage instead of bone
 Bony Fishes (Class Osteichthyes)
 Ray-finned fishes
19-42

43. Figure 19.18B Diversity of fishes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
gill slits (seven pairs)
toothed oral disk
Lamprey, a jawless fish
(lamprey): © Heather Angel/Natural Visions
19-43

44. Figure 19.18B Diversity of fishes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
gill slits
dorsal fin
jaw with teeth
pectoral fin
sand tiger shark, a cartilaginous fish
(shark): © James Watt/Animals Animals
19-44

45. Figure 19.18B Diversity of fishes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
caudal fin second dorsal fin first dorsal fin
anal fin
pelvic
fin
Soldier fish, a bony fish pectoral fin operculum
(bony fish): © Ron & Valerie Taylor/Bruce Coleman, Inc.
19-45

46. 19.19 Amphibians
 Class Amphibia
 Means living on both land and in the water
 Represented by frogs, toads, newts, and
salamanders
 Characteristics
 Adults have small lungs – air enters the mouth by way of
nostrils
 Respiration is supplemented by gas exchange through the
smooth, moist, skin
 Most members lead an amphibious life
 Larval stage lives in water, and adult stage is on land
19-46

47. Figure 19.19 Frogs and salamanders are well-known amphibians
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
tympanum eye moist, smooth skin hindlimb (to side)
Tree frog hindlimb Barred tiger salamander fleshy toes
(frog): © Joe McDonald/Visuals Unlimited; (salamander): © Suzanne L. Collins & Joseph T. Collins/Photo Researchers, Inc.
19-47

48. 19.20 Reptiles
 Class Reptilia
 Exs: Alligators, crocodiles, turtles, snakes, & lizards
 Body is covered with hard scales for protection
 Fertilization is internal, and the female lays leathery,
flexible, shelled eggs
 Ectotherms: “cold-blooded”
19-48

49. Figure 19.20A Reptilian diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
venom gland
fang
rattle
Diamondback rattlesnake
(rattlesnake): © Joel Sartorie/National Geographic/Getty Images 19-49

50. Figure 19.20A Reptilian diversity (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
thick, scaly skin
tail
tongue
nostril
American alligator
(alligator): © OS21/PhotoDisc/Getty RF
19-50

51. 19.20 Class Aves = Birds
 Birds
 Characterized by the presence of feathers
 Birds are adapted to fly
 Forelimbs are modified as wings
 Hollow, light bones
 Horny beak has replaced jaws with teeth
 4 chambered heart
 Endotherms – generate internal heat
19-51

52. Figure 19.20C Types of bird beaks
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Bald eagle 19-52
© Thomas Kitchin/Tom Stack & Associates

53. Figure 19.20C Types of bird beaks (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cardinal 19-53
© Kirtley Perkins/Visuals Unlimited

54. 19.21 Mammals
 Characteristics of mammals:
 Hair: for insulation
 Mammary glands to nurse their young
19-54

55. 19.21 Mammals have hair
and mammary glands
 Monotremes
 Egg – laying mammals
 Exs: platypus
 Marsupials
 Begin their development inside the female’s body, but
they are born in a very immature condition
 Newborns crawl up into a pouch on their mother’s
abdomen
 Exs: koala
19-55

56. Figure 19.21A Monotremes and marsupials
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a. Duckbill platypus,a monotreme of Australian streams
© Fritz Prenzel/Animals Animals
19-56

57. Figure 19.21A Monotremes and marsupials (Cont.)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
b. Virginia oppossum, the only American marsupial
19-57
© Stephen J. Krasemann/Getty Images

58.  Placental mammals
 Placenta
 Organ of exchange between maternal blood and fetal blood
 Some groups
 Ungulates – hoofed mammals – horses, rhinos
 Carnivores – dogs, cats
 Primates – monkeys, gorillas, humans
 Cetaceans – whales and dolphins
 Chiroptera – bats
 Rodents – mice, rats, porcupines
19-58

59. Figure 19.21B Placental mammals
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
White-tailed deer,a forest dwelling ungulate
© Stephen J. Krasemann/Photo Researchers, Inc
19-59

60. Connecting the Concepts:
Chapter 19
 Animals differ in complexity.
 Animals acquire food in diverse ways
 Progression from the multicellular level of
organization to the tissue level, to the organ
level, and finally to the organ system level
19-60