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Introduction To Animal Evolution

Introduction To Animal Evolution. Chapter 32. Animals 1 st appeared in Precambrian in waters, spread to land. 5 criteria that define animal: 1 Animals multicellular, must get food through ingesting other organisms or organic material.

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Introduction To Animal Evolution

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  1. Introduction To Animal Evolution Chapter 32

  2. Animals 1st appeared in Precambrian in waters, spread to land. • 5 criteria that define animal: • 1Animals multicellular, must get food through ingesting other organisms or organic material.

  3. http://www.biology.wustl.edu/plant/simplealgalsystems1.jpg

  4. 2Animals do not have cell walls. • 3Animals have nervous tissue to conduct impulses and muscle tissue for movement. • 4Most animals reproduce sexually with diploid stage being dominant. • 5Animals have special regulatory genes (Hox genes) help zygote form into animal.

  5. Branching of evolutionary tree • 1st branch point splits Parazoa (lack true tissues) from Eumetazoa (true tissues). • Parazoa include sponges. • Eumetazoans divided into 2 major branches, partly based on body symmetry.

  6. http://www.sciencedaily.com/images/2007/07/070705153000.jpg

  7. Radial symmetry - phylum Cnidaria and phylum Ctenophora. • Bilateral symmetry (left and right side) - rest of phyla.

  8. Bilateral symmetry - cephalization, - concentration of sensory equipment towards head. • Difference between 2 groups - presence of germ layers - layers of embryonic tissue that form various tissues and organs.

  9. http://www.guam.net/pub/sshs/depart/science/mancuso/apbiolecture/27_Animalia/Annelida/Image11.gifhttp://www.guam.net/pub/sshs/depart/science/mancuso/apbiolecture/27_Animalia/Annelida/Image11.gif

  10. Bilaterally symmetric animals - 3 germ endoderm (innermost), mesoderm (middle) ectoderm (outermost). • Bilateral animals split according to presence of body cavity (fluid-filled space separating digestive tract from outer body wall) and what cavity looks like.

  11. http://universe-review.ca/I10-13-layers.jpg

  12. Acoelomates (phylum Platyhelminthes) have solid body, lack body cavity. • Some organisms - body cavity - not completely lined by mesoderm. • Pseudocoelomates include rotifers (phylum Rotifera), roundworms (phylum Nematoda).

  13. Coelomates organisms with true coelom, (fluid-filled body cavity completely lined by mesoderm). • Body cavity has many purposes including cushioning organs, allowing them more room to grow.

  14. Coelomate phyla divided based on differences in development. • Many protostomes (mollusks, annelids, arthropods) undergo spiral cleavage. • In many protosomes, blastopore develops into mouth; 2nd opening at opposite end of gastrula develops into anus.

  15. http://chsweb.lr.k12.nj.us/mstanley/outlines/animals/antax/image51.gifhttp://chsweb.lr.k12.nj.us/mstanley/outlines/animals/antax/image51.gif

  16. Zygotes of many deuterostomes undergo radial cleavage. • Deuterostomes - blastopore usually develops into anus, mouth derived from 2nd opening.

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