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Chapter 33 Invertebrates

Chapter 33 Invertebrates. Two views of animal phylogeny: Which is right? Both are useful?. Parazoa Phylum Porifera:  Sponges 1.  Non-moving (sessile) animals 2.  No nerves or muscles (no tissue differentiation) 3.  Mostly marine 4.  Filter feeders:  Collect food particles from water

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Chapter 33 Invertebrates

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  1. Chapter 33 Invertebrates

  2. Two views of animal phylogeny: Which is right? Both are useful?

  3. Parazoa Phylum Porifera:  Sponges 1.  Non-moving (sessile) animals 2.  No nerves or muscles (no tissue differentiation) 3.  Mostly marine 4.  Filter feeders:  Collect food particles from water 5.  Most sponges are hermaphrodites.  Hermaphrodites function as both male and female in sexual reproduction by producing eggs and sperm. **All other animals are in the clade Eumetazoa (true tissues).

  4. Animals probably evolved from colonial, flagellated protists, like this choanoflagellate colony.

  5. Cnidarians Polyp and medusa forms of cnidarians. Radial symmetry with central digestive (gastrovascular) cavity. One opening in the gastrovascular cavity serves as both mouth and anus. Carnivores. Phylum name comes from specialized cells called cnidocytes.  Cnidocytes are stinging cells used for defense and to capture prey.

  6. Purple striped jelly, Pelagia panopyra

  7. Polyps: Sea anemones

  8. Phylum Ctenophora The Comb jellies Resemble cnidarian medusas. Use cilia for locomotion.

  9. Protostomia:  Lophotrochozoa Phylum Platyhelminthes:  Flatworms Sizes range from microscopic up to 20 meters long (tapeworms). Many are parasites.

  10. Class Turbellaria (flatworms) i.  Mostly free-living (non-parasitic) ii.  Feed on small animals, dead animals iii.  Very flat for O2 exchange.  They have no gas exchange organs.

  11. Classes Monogenea/Trematoda i.  Live as parasites ii.  Trematodes parasitize vertebrates.  For example, humans but often with intermediate hosts. 

  12. The life history of a blood fluke (Schistosoma mansoni).

  13. Class Cestoidea – Tapeworms i.  Live as parasites ii.  Head contains suckers and hooks that lock onto the intestinal lining of the host. iii.  The rest of the body is mostly units called proglottids that are sex organs. iv.  Eggs transferred to new hosts by consuming fecal contaminated water.

  14. Anatomy of a tapeworm

  15. Phylum Rotifera:  Rotifers Aquatic Sizes range from 0.5 to 2 mm Complete digestive tract

  16. A rotifer

  17. Lophophorate Phyla:  Bryozoans, Phoronids, & Brachiopods All of these groups have a lophophore.  The lophophore is a horseshoe shaped fold near the mouth that is surrounded by ciliated tentacles. Bryozoans resemble mosses.    - They have a hard exoskeleton.            - They are important as reef builders. Phoronids are marine worms. Brachiopods resemble clams.

  18. A bryozoan

  19. A brachiopod

  20. Phylum Nemertea:  Proboscis (ribbon) worms Up to 30 meters in length These worms have a hydraulically-operated proboscis that is used to capture prey. Closed circulatory system.

  21. Nemertea – Proboscis worms

  22. Phylum Mollusca:  Mollusks Snails, clams, octopi, squids, oysters There are at least 150,000 known species All mollusks have similar body plans: a.  Muscular foot b.  Visceral mass with organs            c.  Mantle that secretes the shell

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