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Evolution of Animals (Metazoa) BIOL 1407. Animal Body Plan Tissues –Absent = Parazoa –Present = Eumetazoa.

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Presentation on theme: "Evolution of Animals (Metazoa) BIOL 1407. Animal Body Plan Tissues –Absent = Parazoa –Present = Eumetazoa."— Presentation transcript:

1 Evolution of Animals (Metazoa) BIOL 1407

2 Animal Body Plan Tissues –Absent = Parazoa –Present = Eumetazoa

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4 Radial Symmetry Encounter environment equally from all sides Sessile, sedentary or planktonic Sea Anemone Feeding Video eo_library.aspxhttp://www.mbayaq.org/efc/video_library/vid eo_library.aspx Then click on “Anemone Feeding” Jellyfish Swimming

5 Bilateral Symmetry Central nervous system in head Active movers Frilled lizard video ayer/animals/reptiles- animals/lizards/lizard_frilled_ontherun.html?f s=animals.nationalgeographic.comhttp://video.nationalgeographic.com/video/pl ayer/animals/reptiles- animals/lizards/lizard_frilled_ontherun.html?f s=animals.nationalgeographic.com Crocodile gallop video brittoncrocs/images/cj-gallop2.mpghttp://www.flmnh.ufl.edu/natsci/herpetology/ brittoncrocs/images/cj-gallop2.mpg

6 Number of Germ Layers Diploblastic: has two germ layers –Endoderm –Ectoderm Triploblastic: has three germ layers –Endoderm –Mesoderm –Ectoderm

7 Question?

8 Body Cavities What is a body cavity? –Fluid-filled cavity separates digestive tract from body wall

9 Body Cavities Advantages: –Fluid cushions organs –Acts as hydrostatic skeleton –Allows internal organs to move independently of body wall –Allows internal organs space for folding

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13 Development Protostome –Fate of blastopore –Type of cleavage: spiral and determinate –Coelom formation Deuterostome –Fate of blastopore –Type of cleavage: radial and indeterminate –Coelom formation

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15 Animation of Spiral and Radial Cleavage

16 Schizocoelous Enterocoelous

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18 Sister Taxon

19 Model of Early Animal Evolution

20 Evolution of Animals Earliest animal fossils Fossilized embryos from China 575 mya

21 Ediacaran Fauna mya Australia Soft-bodied animal fossils What type of symmetry?

22 Ediacaran Fauna Animal fossil Many body segments Head What type of symmetry?

23 Cambrian Explosion mya Animal diversity ↑↑ 50% extant animal phyla in fossil record

24 Burgess Shale Fossils

25 Cambrian Explosion First animals with hard mineralized skeletons 1 st arthropods, chordates & echinoderms

26 Hypotheses for Cambrian Explosion (1) Predator-prey coevolution (2) Rise in atmospheric oxygen levels  ↑ metabolic rate and body size (3) Evolution of Hox genes  developmental flexibility

27 Traditional Phylogenetic Tree Was based on body plans –Tissues absent or present –Type of symmetry –Types of body cavities –Protostomes versus deuterostomes

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29 Modern Phylogenetic Tree Based on molecular data

30 Modern Phylogenetic Tree Reinforces some of traditional tree –Parazoa vs. Eumetazoa –Radial vs. Bilateral –Deuterostomes are a clade

31 Modern Phylogenetic Tree Radical affects on other parts –Body cavity characteristics are analogous –Two main lineages for most invertebrates Lophotrochozoa Ecdysozoa

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33 Lophotrochozoa Clade named for presence of either a: –Lophophore (horse-shoe shaped ciliated feeding apparatus) –Trochophore larva

34 Lophotrochozoa

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36 Ecdysozoa Clade was named for presence of Ecdysis = molting Produce an exoskeleton Must be shed as animal grows

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39 The End Unless otherwise specified, all images in this presentation came from: Campbell, et al Biology, 8 th ed. Pearson Benjamin Cummings. Slides 19 and 28 are from Campbell, et al Biology, 7 th ed.


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