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  1. 1. Invertebrates
  2. 2. Sponges • Simplest Animal • Lack symmetry • Range from a diameter of 1cm to as large as 2m • Most are bag-shaped and have a large internal cavity • Most are sessile (they attach themselves firmly to the sea bottom or submerged surface and stay there for life) • Consist of specialized cells embedded in a gel-like substance called mesophyl • Resembles chopped fruit in gelatin
  3. 3. Sponges Plankton and other tiny organisms are trapped as the water moves through the sponges’ body Waste is carried out the sponges’ as the water moves out Sponges are found mostly in warm shallow seas Some live at great depths A few are even found in fresh water
  4. 4. Sponges Grouped by into three types based on skeletal composition 1. Calcareous sponges have spicules (tiny needle composed of silica or calcium carbonate)
  5. 5. Sponge Reproduction Can reproduce asexually Can regenerate when cut into pieces Will reproduce by shedding a piece then it regenerates into a new sponge Sexual reproduction can take place Most sponges are hermaphrodites (produce both eggs, and sperm) Egg and sperm are produced at different times so that self-fertilization is avoided
  6. 6. Cnidarians Diverse group with two main body types: 1. Medusa: free floating jelly like and often umbrella shaped. 2.Polyp: tube-like and are usually attached to rocks or other objects
  7. 7. Medusa
  8. 8. Polyp
  9. 9. Cnidarians Have a gastrovascular cavity The opening is surrounded by tentacles which have stinging cells called cnidocytes. Each cnidocytes has a small barbed harpoon called a nematocyst Extracellualr digestion: digestion takes place outside of the cell. This is where we first see this, but it takes place in all other species of animals,
  10. 10. Cnidarians Hydrozoans: The most primitive of the cnidarians. Live in colonies Life cycle includes both polyp and medusa stages, Can be both freshwater and marine  Reproduce asexually by forming a bud Many have the ability to reproduce sexually Best known is the Portuguese man of war.
  11. 11. Portuguese Man-of-War
  12. 12. Cnidarians Scyphozoans: “True Jellyfish” Store toxins inside the nematocysts (some species are extremely potent) Active predators the catch and sting prey in their tentacles
  13. 13. Phylum Platyhelminthes Phylum Platyhelminthes-Commonly known as flatworms Simple animals, un-segmented bilaterally symmetrical and 3 cell layers One body cavity: gut Some are parasitic No respiratory or circulatory system Most can reproduce sexually or asexually Oxygen and nutrients pass into body through diffusion
  14. 14. Phylum Platyhelminthes
  15. 15. Phylum Nematoda Phylum Nematoda: roundworms Epidermis secretes hard and flexible cuticle Head has a few very tiny sense organs and mouth No respiratory or circulatory system Bilaterally symmetrical worm-like organism Reproduce sexually Most are dioecious (organisms that have either male or female parts)
  16. 16. Phylum Nematoda
  17. 17. Phylum Mollusca Phylum Mollusca: snails, squid, clams, octopuses, and scallops Soft bodies usually have a “head” and “foot” Often have a exoskeleton Usually have open circulatory system Have sensors to detect chemicals, vibrations, and touch Use the same organ for many functions (for example: the heart and kidneys are important parts of the reproductive, circulatory, and excretory systems)
  18. 18. Phylum Mollusca
  19. 19. Phylum Annelida Phylum Annelida: segmented worms (earthworms), leeches Body usually has bristles Live in a variety of aquatic and land habitats Locomotory, respiratory, and exretory organs are repeated in segments through the body Share a common nervous system, circulatory system, and gut Usually reproduce sexually, but some have the ability to reproduce asexually
  20. 20. Phylum Annelida
  21. 21. Phylum Arthropoda Phylum Arthropoda: spiders, insects, scorpions, and crawfish Exoskeleton made of chitin Segmented body Segments are sometimes fused into 3 parts: head, thorax and abdomen Jointed appendages Bilaterally symmetrical Most have a pair of compound eyes Have an open circulatory system Most lay eggs
  22. 22. Phylum Arthropoda
  23. 23. Phylum Echinodermata Phylum Echinodermata: sea cucumbers, sea urchins, and starfish Many have five-fold symmetry Have a system of internal water filled canals Live in marine habitats Have separate male and females Decentralized nervous system Skeleton composed of calcium Have simple but complete digestive gut Simple radial nervous system
  24. 24. Phylum Echinodermata
  25. 25. Phylum Rotifera Phylum Rotifera: microscopic aquatic animals Soft bodies Have specialized organ systems and a complete digestive tract including a mouth and anus Eat plants or animals through filter feeding Unusual reproduction can reproduce asexually or sexually Bilaterally symmetrical Have a small brain and nervous system
  26. 26. Phylum Rotifera