Ch.32 34 - animals
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Transcript of Ch.32 34 - animals
2007-2008
DomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
Kingdom: AnimalsDomain Eukarya
(Ch. 32, 33, 34)
Introduction to Animal Evolution
Chapter 32
General Features of Animals
• Heterotrophs
• Mobility
• Multicellularity
• Diploidy
• Sexual Reproduction
• Absence of cell wall
• Blastula Formation
• Tissues
Animals probably evolved from colonial protists: A choanoflagellate colony
One hypothesis for the origin of animals from a flagellated protist
Heterotrophs
• Animals cannot make their own food
Mobility
• Animals can perform rapid, complex movements
Multicellularity
• All animals are multicellular
Diploidy
• Most animals are diploid.
Sexual Reproduction
• Most animals reproduce sexually by producing gametes.
Absence of a Cell Wall
• Animals lack rigid cell walls.
Blastula Formation
• The zygote divides and forms a hollow ball of cells.
Early Embryonic Development
Protostomes & Deuterostomes
Body Cavityectoderm
ectoderm
mesodermendoderm
ectodermmesoderm
endoderm
mesodermendoderm
acoelomate
pseudocoelomate
coelomate
coelom cavity
pseudocoel
• Space for organ system development– increase digestive &
reproductive systems
• Coelom– mesoderm & endoderm
interact during development
– allows complex structures to develop• ex. stomach
protostome vs. deuterostome
Body Symmetry
• Radial Symmetry – Parts arranged around a central axis.
• Bilateral – Right and left half.
• Asymmetrical – No symmetry
Tissues & Organs
• Cells are organized by structure and function into:
– Tissues – groups of cells• Muscle tissue, blood, connective tissue
– Organs – groups of tissues• Heart, Lungs, Liver
Origin of Tissues
Segmentation
• Advanced animals are segmented.
Porifera
Cnidaria
Platyhelminthes
sponges jellyfish flatworms roundworms
Nematoda
Mollusca Arthropoda Chordata
Annelida Echinodermata
mollusks
multicellularity
Ancestral Protist
tissues
bilateral symmetry
body cavity
segmentation
Animal Evolution
coelom
starfish vertebrates
endoskeleton
segmentedworms
insectsspiders
backbone
specialization & body complexity
specialized structure & function,muscle & nerve tissue
distinct body plan; cephalization
body complexity digestive & repro sys
digestive sys
body size
redundancy,specialization, mobility
body & brain size, mobility
radial
bilateral
Cambrian Explosion
• Many phyla evolved rapidly over a 40 million year period
• Produced high diversity
• Makes sorting out phylogenetic tree difficult
“Evo-Devo”: Reasons for Cambrian Diversification
• Ecological – Emergence of predator-prey relationships– Evolution of protective outer covering & other
adaptations
• Geological– Enough atmospheric oxygen to support
metabolism
• Genetic– Hox genes- spatial and temporal expression
in developing embryos
Invertebrate: Porifera
• Sponges– no distinct tissues/organs
• A few specialized cell types
– no symmetry– sessile (as adults)
food taken into each cell by endocytosis
Invertebrate: Cnidaria• Jellyfish, hydra, sea anemone, coral
– tissues, but no organs– two cell layers– radial symmetry– predators
• tentacles surround gut opening
• extracellular digestion– release enzymes
into gut cavity– absorption by cells
lining gut
medusapolyp
Stinging cells of Cnidarians
Obviously, we have a movie
Jellyfish Video
Invertebrate: Platyhelminthes
ectoderm
mesoderm
endoderm
• Flatworms– tapeworm, planaria– mostly parasitic– bilaterally symmetrical
• right & left, head (anterior) end
& posterior end – cephalization = development of brain– concentration of sense organs in head
• increased specialization in body plan
Animals nowface the world
head on!
acoelomate
Invertebrate: Nematoda• Roundworms
– bilaterally symmetrical– body cavity
• pseudocoelom = simple body cavity• digestive system
– tube running through length of body (mouth to anus)– many are parasitic
• hookworm
C. elegans
Invertebrate: Mollusca• Mollusks
– slugs, snails, clams, squid– bilaterally symmetrical (with exceptions)– soft bodies, protected by hard shells (mostly)– true coelem
• increases complexity & specialization of internal organs
Invertebrate: Annelida• Segmented worms
– earthworms, leeches– segments
• increase mobility• redundancy in body sections
– 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 + protein
Arthropod groups
insects6 legs, 3 body parts
crustaceansgills, 2 pairs antennaecrab, lobster, barnacles, shrmp
arachnids8 legs, 2 body partsspiders, ticks, scorpions
Invertebrate: Echinodermata• Seastars, sea urchins, sea cucumber
– radially symmetrical as adults– spiny endoskeleton– Deuterostome– coelom loss of bilateral symmetry?
Invertebrate quick check…
• 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?• Which group has no symmetry?
Invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata
• Vertebrates– fish, amphibians, reptiles, birds, mammals– internal bony skeleton
• backbone encasing spinal column
• skull-encased brain
– deuterostome
postanaltail notochord
hollow dorsalnerve cord
pharyngealpouches
Chordata
becomes brain & spinal cord
becomes vertebrae
becomes gills or Eustachian tube
becomes tail or tailbone
Oh, look…your first
baby picture!
Vertebrates: Fish
salmon, trout, sharks
450 mya450 mya
• Characteristics – body structure
• bony & cartilaginous skeleton• jaws & paired appendages (fins)• scales
– body function• gills for gas exchange• two-chambered heart; single loop circulation• ectothermic
– reproduction• external fertilization• external development in egg
gillsbody
Transition to Land
Evolution of tetrapods
Tibia
Femur
Fibula
Humerus Shoulder
RadiusUlna
Tibia
FemurPelvis
Fibula Lobe-finned fish
Humerus
Shoulder
Radius
Ulna
Pelvis
Early amphibian
lung
buccalcavity
glottisclosed
Vertebrates: Amphibians• Characteristics
– body structure• legs (tetrapods)• moist skin
– body function• lungs (positive pressure) & skin for gas exchange• three-chambered heart; 2-loop circulation• ectothermic
– reproduction• external fertilization• external development in aquatic egg• metamorphosis (tadpole to adult)
frogssalamanders toads
350 mya350 mya
Vertebrates: Reptiles250 mya250 mya dinosaurs, turtles lizards, snakesalligators, crocodile
embryoleatheryshell
chorion
allantoisyolk sac
amnion
Vertebrates: Birds (Aves)
• Characteristics – body structure
• feathers & wings• thin, hollow bones
– body function• very efficient lungs & air sacs• four-chambered heart• endothermic
– reproduction• internal fertilization• external development in
amniotic egg• parental care
150 mya150 mya finches, hawk ostrich, turkey
trachea
anteriorair sacs
lung
posteriorair sacs
• Characteristics – body structure
• hair• specialized teeth
– body function• lungs, diaphragm; negative pressure• four-chambered heart• endotherms
– reproduction• internal fertilization• mammary glands make milk• parental care
Vertebrates: Mammals220 mya / 65 mya220 mya / 65 mya mice, ferret
elephants, batswhales, humans
Mammals• 220 million years ago –
evolved from therapsids
• 3 types:– Placental
• Young develop within placenta
– Marsupials• Young are born and then
develop further in the mothers pouch
– Monotremes• Lay eggs
Placental(Human)
Monotreme(Duck-billed Platypus)
Marsupial(Koala)
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 sub-groups of mammals?
That’s the buzz!
AnyQuestions?