Chapter 19Evolution of
AnimalsLecture Outline
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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 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
19-4
Symmetry & Anatomical Terms
radial symmetry bilateral symmetry
posterior
anterior
dorsal
ventral
19.4 Phylum Porifera: Sponges
Sponges Only Animals without true tissues Asymmetrical body plan
Body is perforated by pores Filter feeder
19-5
Figure 19.4 Sponge anatomy (Cont.)
19-6
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Sponge organization collar cell (choanocyte)
flagellum
spicule
pore
amoeboid cell
epidermal cell
amoeboidcellnucleus
H2O inthroughpores
osculum H2O out
centralcavity
collarsponge wall
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
Figure 19.5A Cnidarian diversity
19-8
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
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
Figure 19.6 Planarian anatomy (Cont.)
19-11
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auricle eye spots
5 mmsense organs© Tom E. Adams/Peter Arnold/Photolibrary
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
Figure 19.7A Tapeworm (Taenia solium) anatomy and life cycle
19-13
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Bladder worm attachesto human intestinewhere it matures into atapeworm. As the tapeworm grows, proglottids mature, and eventually fill with eggs.
1.0 mm250 μm
hooks
sucker scolex proglottid
(left): © James Webb/Phototake; (right): © John D. Cunningham/Visuals Unlimited
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
Figure 19.8 Body cavities
19-15
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Acoelomate (flatworms) Pseudocoelomate (roundworms) Coelomate (molluscs, annelids, arthropods,echinoderms, chordates)
endoderm mesoderm
pseudocoelom endoderm mesoderm
digestive cavity ectoderm
coelom mesentery mesoderm
ectodermdigestive cavityendodermdigestive cavity ectoderm
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
Figure 19.9B Three groups of molluscs
Gastropods Meaning
stomach-footed
Includes snails
Animal moves
by muscle contractions that pass along its ventrally flattened foot
19-17
19.9 Molluscs have a
three-part body plan
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eyes
growth linefoot
spiral shell
tentaclegills
footmantle
Three-stripedorisnudibranch
Land snail
(nudibranch): © Kenneth W. Fink/Bruce Coleman, Inc
1 Gastropods
Figure 19.9B Three groups of molluscs (Cont.)
Cephalopods (meaning head-footed) including octopuses, squids, and nautiluses Foot has evolved into tentacles about the head
19-18
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(nautilus): © Douglas Faulkner/Photo Researchers, Inc
2
arm
eye
suckers
Two-spotted octopusCephalopods
Chambered nautilus
shell
tentacles
eye
Figure 19.9B Three groups of molluscs (Cont.)
Bivalves (shells have two part) including clams, oysters, scallops, and mussels Clam is a filter feeder and food particles and water enter the mantle cavity by way of a siphon
19-19
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(scallop): Courtesy Larry S. Roberts (mussel): © Fred Whitehead/Animals Animals;
growth linesof shell
Blue mussel
3
tentacleson mantle
shelleyes
Bivalves
Bay scallop
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
19-21
Figure 19.10A Earthworm anatomy
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dorsal blood vessel
nephridium
pharynx
mouthesophagus
brain
coelomhearts (5pairs)
seminal vesicle
ventral blood vessel
ventral nerve cord
clitellum
anus
crop
Figure 19.10B Other annelids (Cont.)
19-22
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c. Medicinal leech
anterior sucker
Posteriorsucker
© St. Bartholomews Hospital/SPL/Photo Researchers, Inc.
Phylum Nematoda: Roundworms
Roundworms = Nematodes
Nonsegmented
Free-living and parasitic species
Exs: Pinworms & Hookworms
19-23
Figure 19.11A Ascaris
19-24
Figure 19.11B Encysted Trichinella larva.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
SEM 400x
cyst
© James Solliday/Biological Photo Service
Phylum: Arthropoda
Extremely diverse – more than 1 million species
Six characteristics1.Jointed appendages
2.Exoskeleton
3.Segmentation
4.Well-developed nervous system
5.Adaptation of respiratory organs
6.Reduced competition through metamorphosis
19-25
Figure 19.12A Exoskeleton and jointed appendages of a crayfish
19-26
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AbdomenCephalothorax
antennule
antennacompound
eyetelson
anusgills
mouth
uropods
first walking leg(pinching claw)
second walking leg
third walking leg
fourth walking leg
fifth walking leg
swimmerets
Figure 19.12B Monarch butterfly metamorphosis
19-27
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Caterpillar, eating stage Pupa, cocoon stage Metamorphosis occurs Emergence of adult Butterfly, adult stage
(all): © John Shaw/Tom Stack & Associates
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
Figure 19.13A Crustacean diversity
19-29
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(crab): © Michael Lustbader/Photo Researchers, Inc
legs (5 pairs)
mouth
Sally light foot crab
eye
Figure 19.13B Centipede and millipede
19-30
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legs
antenna
Centipede
Millipede
antenna
legs
(centipede): © David M. Dennis/Animals Animals; (millipede): © Geof de Feu/Imagestate
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
Figure 19.13C A spider and two of its relatives
19-32
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Black widow spider
Horseshoe crab
compound eye
Giantscorpion
cephalothorax
walking legs
abdomen
pedipalp
stinger
telson
abdomen cephalothorax
(scorpion): © Tom McHugh/Photo Researchers, Inc.; (horseshoe crab): © Jana R. Jirak/Visuals Unlimited; (spider): © Ken Lucas
Figure 19.14 Insect diversity (Cont.)
19-33
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antennae
chewingmouthparts
Grasshopper
Leathery forewingscover membranoushindwings
© Chris Mattison/Frank Lane Picture Agency/Corbis
Figure 19.14 Insect diversity (Cont.)
19-34
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Butterfly
scale-coveredwings
suckingmouthparts
© McDonald Wildlife Photography/Animals Animals
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
Figure 19.15 Echinoderm structure and diversity
19-36
digestivegland tube feet
skin gill
anusstomach
sieve plate
arm
endoskeletal plates
eyespot
ampulla
coelom
gonad
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 19.15 Echinoderm structure and diversity (Cont.)
19-37Seaurchin
spines
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© Randy Morse/Animals Animals
Figure 19.15 Echinoderm structure and diversity (Cont.)
19-38
Sand dollar
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Andrew J. Martinez/Photo Researchers, Inc.
19.16 Phylum Chordata
Simple Chordates Exs: Lancelet & Tunicate
4 characteristics1. 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
Figure 19.17A The invertebrate chordates
19-40a: © Heather Angel/Natural Visions; b: © Rick Harbo
a.Tunicate b.Lancelet
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Figure 19.17B Phylogenetic tree of the chordates
19-41
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* includes birds
Lancelets
Tunicates
Jawless Fishes
Cartilaginous Fishes
Ray-finned Fishes
Lobe-finned Fishes
Amphibians
Reptiles*
Mammals
ancestralchordate
vertebrae
jaws
bonyskeleton
lungs
limbs
amniotic egg
mammary glandcommon ancestor
Ch
ord
ates
Am
nio
tes
Tet
rap
od
s
Gn
ath
ost
om
es
Ver
teb
rate
s
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
Figure 19.18B Diversity of fishes
19-43
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toothed oral disk
gill slits (seven pairs)
Lamprey, a jawless fish
(lamprey): © Heather Angel/Natural Visions
Figure 19.18B Diversity of fishes
19-44
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dorsal fingill slits
jaw with teeth
pectoral fin
sand tiger shark, a cartilaginous fish
(shark): © James Watt/Animals Animals
Figure 19.18B Diversity of fishes
19-45
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operculumpectoral finSoldier fish, a bony fish
anal finpelvicfin
caudal fin second dorsal fin first dorsal fin
(bony fish): © Ron & Valerie Taylor/Bruce Coleman, Inc.
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
Figure 19.19 Frogs and salamanders are well-known amphibians
19-47
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Tree frog hindlimb Barred tiger salamander fleshy toes
hindlimb (to side)tympanum eye moist, smooth skin
(frog): © Joe McDonald/Visuals Unlimited; (salamander): © Suzanne L. Collins & Joseph T. Collins/Photo Researchers, Inc.
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
Figure 19.20A Reptilian diversity (Cont.)
19-49
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venom gland
fang
rattle
Diamondback rattlesnake(rattlesnake): © Joel Sartorie/National Geographic/Getty Images
Figure 19.20A Reptilian diversity (Cont.)
19-50
tail
American alligator
nostriltongue
thick, scaly skin
(alligator): © OS21/PhotoDisc/Getty RF
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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
Figure 19.20C Types of bird beaks
19-52
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© Thomas Kitchin/Tom Stack & Associates
Bald eagle
Figure 19.20C Types of bird beaks (Cont.)
19-53
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Cardinal© Kirtley Perkins/Visuals Unlimited
19.21 Mammals
Characteristics of mammals:
Hair: for insulation
Mammary glands to nurse their young
19-54
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
Figure 19.21A Monotremes and marsupials
19-56© Fritz Prenzel/Animals Animals
a. Duckbill platypus,a monotreme of Australian streams
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Figure 19.21A Monotremes and marsupials (Cont.)
19-57
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© Stephen J. Krasemann/Getty Images
b. Virginia oppossum, the only American marsupial
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
Figure 19.21B Placental mammals
19-59
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White-tailed deer,a forest dwelling ungulate
© Stephen J. Krasemann/Photo Researchers, Inc
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
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