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Chapter 28 Simple Invertebrates. 28-1: Sponges  Domain: Eukarya  Kingdom: Animalia  Phylum: Porifera.

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Presentation on theme: "Chapter 28 Simple Invertebrates. 28-1: Sponges  Domain: Eukarya  Kingdom: Animalia  Phylum: Porifera."— Presentation transcript:

1 Chapter 28 Simple Invertebrates

2 28-1: Sponges  Domain: Eukarya  Kingdom: Animalia  Phylum: Porifera

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4 General Characteristics  No symmetry  No tissues / organs  Cells can recognize other cells  Reorganize when separated  Sessile: do not move as adults  Diameter ranges from 1cm to 2m

5 Body Characteristics  Ostia: Pores on outer wall  Osculum: Large hole for water to exit  Choanocytes: cells with flagella that line internal cavity  Move water through body cavity  Trap food particles and digest  Also called Collar Cells  Amoebocytes: cells that move around in sponge body to transport nutrients / wastes

6 Pore cells = Ostia Collar cell = choanocyte

7 Sponge Feeding

8 Sponge “Skeletons”  Most have Spicules: tiny needles made of calcium carbonate or silica  Some sponges have spongin: flexible protein fibers

9 3 Classes of Sponges 1.Calcareous Sponges Skeletons made of calcium carbonate spiculesSkeletons made of calcium carbonate spicules 2.Glass Sponges Spicules made of silicaSpicules made of silica 3.Demosponges Skeletons made of spicules and sponginSkeletons made of spicules and spongin

10 Asexual Reproduction  Can regenerate when cut into pieces  Fragmentation  Budding: smaller individuals grow off sides of larger individual  Form gemmules: when living conditions become too poor, amoebocytes encase in protective shells to survive

11 Sexual Reproduction  Most sponges are hermaphrodites  Sperm released into water  Sperm cells from another sponge enter through pores  Larvae develop from fertilized eggs and swim away

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13 Sponge Defenses  Sponges are soft (easily eaten)  Sponges are sessile (can’t swim away)  Protect selves by producing chemicals  These chemicals have been used by humans for  Antibiotics  Pain killers / Sedatives  Cancer treatments

14 28-2 : Cnidarians  Two body forms:  Medusa: free-floating umbrella-like  Polyp: tubelike and attached at base  Polyps are sessile…  Attach to floor / object with Basal Disk  Both show radial symmetry  Tentacles surround mouth  Enters into gastrovascular cavity

15 2 layers of cells  Ectoderm on outside  Endoderm on inside  Mesoglea: layer of “jelly” between the 2 layers  Cells arranged into tissues

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17 Cnidocytes  Cnidocytes: Stinging cells on tentacles  Contain Nematocysts: small, barbed harpoons  Some nematocysts have deadly toxin, some with chemicals to just stun  Used for defense and to spear prey  Tentacles pull food into mouth

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19 3 classes  Hydrozoans  Ex: Hydra, Portuguese-Man-of- War  Scyphozoans  Ex: Jellyfish  Anthozoans  Ex: Sea Anemones, Corals

20 Hydrozoans  Most are Colonial  Life cycle includes both polyp and medusa forms  Live in freshwater and marine  Freshwater example: Hydra  Marine hydrozoans are among most toxic (deadly to humans)

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22 Hydra: freshwater Hydrozoans  Most of life is individual polyp  Stick to surfaces with sticky secretion from basal disk (bottom)  Can glide on basal disk or tumble

23 Reproduction in Hydrozoans  Most capable of sexual reproduction  Some are hermaphrodites  Can reproduce asexually also  budding

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25 Scyphozoans  “True” Jellyfish  Can be small (thimble-sized) to extremely large (queen-sized mattress)  Go through polyp stage at some point in life cycle

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27 Anthozoans  Corals and Sea Anemones  Have symbiotic algae living in cells to help provide energy  Sea Anemones are soft-bodied  Corals secrete calcium carbonate outer skeletons  Only top layer is alive, rest is old skeletons of dead corals  Build up into reefs

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29 28-3: Flatworms & Roundworms Flatworms

30 Flatworms  Phylum Platyhelminthes  More complex than sponges and cnidarians  Have middle tissue layer  Tissues organized into organs  Bilateral symmetry  Cephalization

31 Since they are flat…  Each cell close enough to outside to get O 2 and release CO 2  Gastrovascular cavity branched and close to all tissues (nutrients to cells easily)  Still have just 1 opening

32 3 classes 1.Turbellaria:  Free-living  Most marine  Freshwater: Planaria

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34 Planarian Feeding  Use muscular tube that extends from center of GVC  Called Pharynx  Eat small protists or dead / dying animals

35 Planaria Reproduction  Attach posterior end to rock, pull apart into 2  Regenerate  Sexually reproduce by exchanging sperm with another planarian  Hermaphrodites

36 2. Cestoda  Parasitic  Commonly called Tapeworms  Hooks and suckers on head to attach inside host’s intestine  Absorb nutrients from host  Produce proglottids: string of rectangular body segments that break off in reproduction

37  Can grow to be 40 ft. long

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39 3. Trematoda  AKA “Flukes”  Parasites:  Live in host (endoparasites)  Live on host (ectoparasites)  Ex: Schistosoma  Disease: Schistosomiasis

40 Enter through skin (hookworm) and burrows to blood vessels to lay eggs Block blood vessels (internal bleeding and liver damage)

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42 Roundworms  Phylum Nematoda  Have pseudocoelom  Simplest animals with one-way digestive tract (mouth and anus!)  Most microscopic  One square yard of forest soil can have 3 million nematodes

43 Pseudocoelom  “False” body cavity  Filled with fluid to act as simple respiratory and circulatory systems  O 2, CO 2, nutrients flow through body

44 Can be human parasites…  Ascaris lumbricoides  Infects lungs, gall bladder, pancreas Trichinella spiralis Infects muscles

45 Elephantitis: blockage of lymph system by nematode enters through skin in water

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