EVOLUTION OF ANIMALS

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EVOLUTION OF ANIMALS
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CHARACTERISTICS OF ANIMALS

• Multicellular
• Eukaryotic
• Heterotrophic (ingestion)
• No cell walls
• Nervous muscle tissue
• Sexual reproduction
• Hox genes

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Early Embryonic Development
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ANIMAL DIVERSITY BASED ON BODY PLAN
4) Protostome/Deuterostome
3) Body cavity
2) Symmetry
1) Tissues
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SYMMETRY
Anterior/posterior Dorsal/ventral Cephalization
(movement) Germ layers diploblastic/triplobla
stic
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BODY CAVITY

• Acoelomate no body cavity between digestive
  tract outer wall
• Pseudocoelomate cavity not completely lined by
  tissue from mesoderm
• Coelomate fluid filled cavity completely lined
  by tissue from mesoderm
• cushions organs, allows for growth
  movement
• hydrostatic skeleton (earthworms)

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DEVELOPMENT
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Phylogeny based on SSU-rRNA
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TROCHOPHORE LARVA
ECDYSIS
LOPHOPHORATE LARVA
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ANIMAL PHYLOGENY
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• Porifera
• (parazoans) tissues
• sponges

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• Cnidaria gastrovascular cavity, stinging cells,
  polyp medusa
• Scyphozoa
• jelly fish
• Hydrozoa
• hydra,
• Portuguese man owar
• Anthozoa
• coral, sea anemones

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LIFE CYCLE OF OBELIA
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CNIDARIA
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PLATYHELMINTHES
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http//ngm.nationalgeographic.com/2008/06/nudibran
chs/doubilet-photography
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Polychaeta
Classification Annelida. Class
Polychaeta Characteristics Segmented Worms that
live mostly in marine environment. Have parapodia
on each body segment. Motion.Gills (Blood
Vessels) Examples clam worm, lugworm, sand
worm Other names Bristle Worms Environment
marine, land, parasites Interesting Fact
Pompeii Worm is endemic to the hydrothermal vents
of the Pacific Ocean.
Clam Worm
Parapodia --- polysaccharide chitin
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Fig 34-2. Chordate characteristics. All chordates
possess the four trademarks of the phylum a
notochord a dorsal, hollow nerve cord
pharyngeal slits and a muscular, postanal tail.
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Fig 34-39. Upright posture predates an enlarged
brain in human evolution. (a) Lucy, a
3.24-million-year-old skeleton, represents the
hominid species Australopithecus afarensis .
Fragments of the pelvis and skull show that A.
afarensis was bipedal, though the arms indicate
that Lucy was also adapted for arboreal
locomotion. (b) The Laetoli footprints, over 3.5
million years old, confirm that upright posture
evolved quite early in hominid history.
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