Transcript Chapter 7 a
Kingdom Animalia • • • • Multicellular Heterotrophs Lack cell walls Embryology – Blastula stage Animal diversity • Simple, cellular level of organization to complex • Invertebrates to vertebrates – Most animals (>95%) are inverts – Aside from very successful insects, most animals are marine – Diverse morphologies, habitats, and adaptations Phylum Porifera • Sponges • Habitat – Mostly marine, few freshwater – sessile • Body plan = asymmetry • Suspension filter feeders • Cellular level (lacks true tissues and organs) • Cells with specific functions – – – – Porocytes: water canal Pinacocytes: flat protective cells Choanocytes: “collar cells” capture food (plankton) Amebocytes: transport food; differentiate into other cells – Spicules: siliceous or calcareous skeletal structures • Reproduction – Asexual budding – Sexual broadcast spawn • Diverse types & habitats – Tropical to temperate encrusting – Subtropical bath sponges – Deep water glass sponge Phylum Cnidaria (nigh-dare-ia) • Jellyfish, sea anemones, coral • Nearly all marine • Radial symmetry • Two forms: medusa (swimming) and polyp • Tissue level • Reproduction – Sexual and budding • Stinging cells – cnidocytes • Tissue layer: 2 layers – Epidermis and gastrodermis – Mesoglea is middle jelly layer rather than a true tissue Class Hydrozoa • Individual polyps or colonies of specialized polyps – Feeding, reproductive, defense • Sessile colonies • Drifting colonies Class Scyphozoa • Dominant medusae stage – Examples • Sea Nettle • Moon Jelly • Upside-down Jelly • Close relative – Class Cubozoa • Tropical • Potent toxins Class Anthozoa • Solitary or colonial polyps w/out medusae stage – Sea anemones • Some with zooxanthellae symbionts – Photosynthesizing protists – Corals • CaCO3 skeletons • Environmentally valuable reefs • Extremely susceptible to negative impacts – Pollution, increased temp., etc Phylum Ctenophora • Comb jellies • All marine • Swim with 8 rows of ciliary combs or ctenes • Use tentacles with colloblasts to capture prey – Adhesive, non-stinging cells Phylum Platyhelminthes • • • • Flatworms Bilateral symmetry Organ level Cerebral ganglia – Simple brain • Reproduction: hermaphrodites – Asexual and Sexual • Many parasitic • Incomplete gut • Three tissue layers Opisthorchis sinensis, Chinese liver fluke Opisthorchis lifecycle Cestoda • Similar to this mammal tapeworm example, are the marine parasitic tapeworms, “…as dense as seaweed forests, that live in the guts of sharks.” Cestoda scolexes Cestode proglottid 2 Testes Ovary Yolk gland Phylum Nemertea • • • • Ribbon worms Circulatory system Complete gut Eversible proboscis Phylum Nematoda • Roundworms • All environments – Marine sediments (feed on bacteria) – Parasitic to most marine animals • Complete gut • Reproduction – Always sexual One of the biggest marine parasites measures 13 meters and is two centimeters in diameter …found in the placenta of the sperm whale. Phylum Mollusca • Very diverse • Will discuss in more detail… Phylum Annelida • Segmented worms – Earthworms – Leeches – Polychaetes • Repetitive body parts • Hydrostatic skeleton – Flexibility and strength • • • • • Longitudinal & circular muscles Coelomates Closed circulatory system Excretory organs Marine, moist land, and some freshwater • Bilateral symmetry • Some parasitic Nereis • Class Polychaeta • Adaptations to predatory lifestyle – Eyes, tentacles, jaws, etc • Coelom – Protective gut cavity • Parapodia – w/setae – Respiratory, nervous, and locomotion