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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


4 Radial Symmetry Encounter environment equally from all sides Sessile, sedentary or planktonic Sea Anemone Feeding Video eo_library.aspx 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.com ayer/animals/reptiles- animals/lizards/lizard_frilled_ontherun.html?f Crocodile gallop video brittoncrocs/images/cj-gallop2.mpg 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




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


15 Animation of Spiral and Radial Cleavage

16 Schizocoelous Enterocoelous


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 565-550 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 535-525 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


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


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

34 Lophotrochozoa


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



39 The End Unless otherwise specified, all images in this presentation came from: Campbell, et al. 2008. Biology, 8 th ed. Pearson Benjamin Cummings. Slides 19 and 28 are from Campbell, et al. 2005. Biology, 7 th ed.

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