Marine Invertebrates

1. Marine Invertebrates

4. 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 have true tissues

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

8. 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.

15. Purple striped jelly, Pelagia panopyra

16. Polyps: Sea anemones

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

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

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

24. Classes Trematoda   Live as parasites   Trematodes parasitize vertebrates.  (For example, humans but often with intermediate hosts) 

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

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

27. Anatomy of a tapeworm

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

29. A rotifer

30. 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.

31. A bryozoan

32. A brachiopod

33. 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.

34. Nemertea – Proboscis worms

35. 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

42. Bivalvia Shells divided into two parts.  Gills are used for feeding and gas exchange. Example:  Clams, oysters

44. Dreissena polymorpha Zebra mussel

45. Cephalopoda Rapid movement; well-developed nervous systems.  Example:  Octopus, squid, nautilus

47. Phylum Annelida:  Segmented worms Sizes range from 1 mm to 3 meters in length. Each segment contains a pair of excretory tubes called metanephridia. Annelids are hermaphrodites that cross-fertilize. Three classes: a.  Oligochaeta – earthworms            b.  Polychaeta – mostly marine            c.  Hirudinea – leeches