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Unicellular Marine Organisms

Unicellular Marine Organisms. Bacteria. Most abundant organisms on earth Widely distributed in the ocean Microscopic single-celled organisms Three basic shapes: Coccus = round Bacilli = rod shaped Spirilla = corkscrew. Decay bacteria.

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Unicellular Marine Organisms

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  1. Unicellular Marine Organisms

  2. Bacteria • Most abundant organisms on earth • Widely distributed in the ocean • Microscopic single-celled organisms • Three basic shapes: • Coccus = round • Bacilli = rod shaped • Spirilla = corkscrew

  3. Decay bacteria • Bacteria break down organic matter into smaller molecules that are released into the ocean • Called “Decomposers” • Most abundant in bottom sediments where dead matter accumulates • Thrive in warm, moist, dark and nutrient rich environments • Chemosynthesis- process by which sulfur bacteria derive energy from chemicals

  4. Blue-Green Bacteria • Cyanobacteria- type of bacteria that contain chlorophyll and lack a membrane bound nucleus • The only bacteria that are photosynthetic • Found throughout the oceans and are very hardy

  5. Diatoms • Among the most common organisms in the ocean • Single-celled protists that usually float or drift near the surface • Classified as phytoplankton (“plant wanderers”) • Contain chlorophyll and perform photosynthesis • Have cell walls made of silica

  6. Diatom Diversity and Life Functions • Over 25,000 species of diatoms • Most are found in the cold waters of the world • Classified in phylum Chrysophyta (“golden algae”) • Classified according to their shape • Round = centric diatoms • Pen-shaped = pennate • Spines = shape that prevent sinking

  7. Can reproduce asexually or sexually • When diatoms die, their glassy cell walls remain and accumulate on the sea floor • Layer of these deposits are called diatomaceous earth (excellent filtering material) • Almost all animals in the sea ultimately depend on diatoms for food

  8. Problems from Diatoms • Algal blooms- sudden increase in diatom populations • Brown tide- water becomes so clouded with algae that the waters turn brown

  9. Dinoflagellates • Another group of protists often found near the surface • Classified in phylum Pyrrophyta “red (or fire) algae” • Have two flagella that help move the dinoflagellate along (diatoms cannot propel themselves at all) • Contain chloroplasts and can make their own food • Have cell walls made of cellulose like plants

  10. Effects of dinoflagellates • Bioluminescence- ability of an organism to produce light • Noctiluca have the ability to emit a greenish-blue light when stimulated

  11. Red Tide • Water suddenly turns a reddish color with no warning • Occurs because of a sudden explosion of the Gymnodinium dinoflagellate population • Toxins released by the organisms accumulate in shellfish that eat the algae • In turn, the organisms that feed on the shellfish (fish, marine birds, humans) are poisoned • Algal bloom also reduces oxygen levels in the water which contributes to a fish kill

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