GEOL 3070 Lecture 27: Marine Invertebrate Animals

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Geological Sciences
GEOL 3070
Thomas Marchitto

Marine Invertebrate Animals Thursday, April 20, 20111:01 AM Invertebrate Phyla (Kingdom Animalia) • >90% of all living (and fossil) animals are invertebrates • Lack bony internal skeleton • 33 phyla on Earth today • 5 phyla surveyed here (particularly conspicuous in ocean) I. Porifera (sponges) • Benthic, sessile • Spongin with network of opal (or calcite)spicules • Flagellated collar cells sweep water out while capturing food particles • Digestion carried out by ameboid cells No digestive, circulatory, respiratory, or nervous systems • II. Cnidaria • Toxic stinging cells: cnidocytes (aka nematocysts) • Repel predators and capture prey • Radial symmetry • Primitive nervous system • Food drawn to mouth and simple dead-end digestive cavity A. Medusae (jellies) • Predatory zooplankton (swim weekly) • Bell-shaped fringed with muscle and tentacles B. Polyps: sea anemones • Benthic and mainly sessile, with basal disc (allows them to attach to the bottom) C. Polyps: corals • Most live in CaCO 3aragonite) cups called corallites • Usually colonial • Hermatypic: reef builders • Ahermatypic: Don't build reefs (live in solitary form) ○ Usually deep sea corals 1. Zooxanthellae • Most reef corals have symbiotic algae (Dinoflagellates) • Algae release organic molecules to coral (food) • Coral supplies nutrients (N,P) and C2 to algae • Algae gives reefs their color (also benthic and encrusting algae) 2. Limitations on Reef Corals (hermatypic) • Optimal temperature range 23-29°C (tropics) • Most live shallower than 25m (need sunlight for algae) • Can't tolerate low salinities (runoff) • Killed by high turbinity (runoff) • Killed by exposure to air for more than a few hours 3. Atolls • Ring of coral around submerged volcanoes • Volcano must sink slower than coral growth (~1 cm/yr) 4. Reef Ecosystems • ~100X more productive than typical tropical waters • Efficient trapping and recycling of nutrients 2 • Great Barrier Reef: >2900 reefs covering 344,000 km • Reefs are the most diverse marine ecosystems • Provide habitat and breeding ground for ○ ~3M marine species ○ ~1/3 of all fish species • Fish, mollusk
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