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An Introduction to Invertebrates

An Introduction to Invertebrates. Chapter 33. 1 million species of animals… 95% are invertebrates!. 34-36 phyla of the Animal Kingdom. Lower Invertebrates. 5,500 species, mostly marine sponges Parazoans 2 layers unspecialized cells, no tissues Asymmetrical Suspension (filter) feeders

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An Introduction to Invertebrates

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  1. An Introduction to Invertebrates Chapter 33

  2. 1 million species of animals… • 95% are invertebrates!

  3. 34-36 phyla of the AnimalKingdom

  4. Lower Invertebrates

  5. 5,500 species, mostly marine sponges • Parazoans • 2 layers unspecialized cells, no tissues • Asymmetrical • Suspension (filter) feeders • Sessile • Hermaphroditic, but cross fertilize • Regenerative abilities Phylum Porifera

  6. : opening : CaCO3 skeletal fibers

  7. ~10,000 species (jellyfish, sea anemones) • Live in shallow coastal marine waters • Eumetazoa • Organized into tissues • Diploblastic – 2 germ layers • Radially symmetrical • Carnivorous • Have stinging tentacles called cnidocytes • Gastrovascular cavity • Digestive system (only one opening) Phylum Cnidaria

  8. Life Cycle

  9. Class Hydrozoa: hydra Class Scyphozoa: sea nettle Class Cubozoa: box jelly Class Anthozoa: brain coral

  10. All Marine (100 species) • Comb Jellies • Resemble Cnidarians • Lack stinging cells; have sticky cells to capture prey 3. Phylum Ctenophora

  11. Bilaterally symmetrical • Triploblastic (all germ layers) • Gastrovascular cavity (both ends) • Sexual and asexual reproduction • Complex tissues: nerves and brain • Acoelomate • Mostly parasitic Phylum Platyhelminthes

  12. Class Turberellaria: planaria Class Trematoda: liver fluke Class Monogenea: Dermophthirius Class Cestoda: tapeworm

  13. Mainly freshwater • Pseudocoelomate • Complete digestive system • Use cilia to draw water into mouth • “wheel bearer” • Parthenogenesis: sexual-female dominate Phylum Rotifera

  14. Bilateral symmetry • Coelomates • Triploblastic • Marine • Lophophores for feeding • Horseshoe-shaped/circular crown of ciliated tentacles surrounding mouth Phylum Braciopoda

  15. Bilateral symmetry • Triploblastic • Acoelomate • Mostly marine • Proboscis used to probe environment • Simple circulatory system – no heart, blood movement through body contractions • Complete digestive system Phylum Nemertea

  16. 25,000 species • Bilateral Symmetrical • Organized into Tissues • Complete digestive tract • Sexual reproduction • Pseudocoelomic Phylum Nematoda

  17. Protostome • Coelomates • Segmented • Complete digestive system • Closed circulatory system • Nervous system • cerebral ganglia and ventral nerve cord • Hermaphrodites • cross fertilized - clitellum Phylum Annelida

  18. Class Polychaeta: bristle worms Class Oligochaeta: earth worms Class Hirudinea: leeches

  19. Higher Invertebrates

  20. Protostomes • Coelomates • Body plan – 3 parts • Muscular head-foot (soft-bodied) for locomotion • Visceral miss – internal organs • Surrounded by mantle (CaCO3) • Some molluscs also have: • Mantle cavity – contains gills, anus, excretory pores • Radula for scraping food from surfaces • Most dioecious Phylum Mollusca

  21. Class Gastropoda: snails Class Polyplacophora: chitons Class Cephalopoda: octopus Class Bivalvia: clams

  22. Two out of every three known species of animals are arthropods • Members of the phylum Arthropoda are found in nearly all habitats of the biosphere • Largest phylum (1,000,000 species) • Coelomates • Protostome Phylum Arthropoda

  23. Segmentation • allows for specialization of body parts • Head • Thorax • Abdomen • Hard exoskeleton • Cuticle made with chitin • Prevents water loss: move onto land • Organisms must molt (ectdysis) • Jointed appendages • allows for specialization • Walking • Feeding • Copulation

  24. Subphylum Cheliceriformes: spiders, horseshoe crabs, scorpions, ticks, mites Subphylum Myriopoda: centipedes, millipedes

  25. Subphylum Hexapoda: insects Subphylum Crustacea: crabs, lobsters, crayfish, shrimp

  26. Radial symmetry • Deuterostomes • Coelomates • Sessile or sedentary marine forms • Well developed organs and systems • Have an internal skeleton • Water vascular system • tube feet that function for locomotion, feeding, and gas exchange • Dioecious Phylum Echinodermata

  27. Class Asteroidea: sea stars Class Ophiuroidea: brittle stars Class Echinoidea: sea urchins

  28. Class Crinoidea: sea lilies Class Holothuroidea: sea cucumbers Class Concentriclodea: sea daisies

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