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Time Line of Animal Evolution

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Presentation on theme: "Time Line of Animal Evolution"— Presentation transcript:

1 Time Line of Animal Evolution
1st Fossil evidence of animals 570 mya = Proterozoic Eon Adaptive radiation in early Cambrian Period of the Phanerozoic Eon Cambrian Explosion due to increased oxygen in atmosphere more energy predators become more mobile

2 Evolution of Animals Some type of Protist mutated to become multicellular Multicellular organisms start as a single cell (zygote) and grow into organisms with groups of specialized cells performing different functions All animals are multicellular

3 multicellular

4 Proterospongia = Protist & common ancestor to all animals?

5 Proterospongia: Colonial, Unicellular Protists

6 Sponge collar cells

7 Phylum Porifera Sponges 3 types of cells Collar cells Amoebocytes
Epidermis cells (protective outer layer of cells) No tissues Cells held together by jelly like substance Skeleton of spicules & spongin protein

8

9 Intracelluar digestion
Collar cells take in food by endocytosis Food digested in food vacuoles Some food passed to amoebocytes Amoebocytes carry food around sponge body. (circulaton)

10 Other Porifera Traits Asymmetrical = no symmetry
Respiration by diffusion Excretion by diffusion

11 All other Animals have True Tissues
Multi cellular

12 Phylum Cnidaria Have stinging cells = cnidocytes Have tentacles
Have myocytes = muscle like cells that contract 1st predator Radial symmetry = sit and wait predator 1st nervous system = nerve net & eye spots Phylum Cnidaria

13 Nerve net

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15 Cnidocytes

16 Digestion & Circulation
Have gastrovascular cavity for digestion & circulation 1st extra cellular digestion – cells lining GVC secrete digestive enzymes Evolutionary advantage = can eat larger food Cillia push digested food around the GVC GVC branches into all tentacles: comes near all cells

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18 Respiration & Excretion
Respiration by diffusion Excretion by diffusion Both are possible since entire body is only a few cell layers away from water

19 Reproduction = complex life cycle
Medusa = swimming Polyp = sessile Medusa =sexual Egg & sperm External fertilizaion Polyp = asexual budding


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