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2. Chapter 5 The Microbial World KINGDOM PROTISTA

3. Diatoms Diatoms: Diatoms: –Photosynthetic –Yellow-brown color in life is a result of photosynthetic pigments, chlorophyll A and C and carotenoids –Shell of silica called a frustule –Most important primary producer on Earth –Mostly solitary and unicellular –Some can form colonies

5. Diatoms Diatoms Diatoms –Around half of the 12, 000 known species are marine –Most are planktonic –Store excess energy as an oil which also aids in buoyancy –Tiny pores in shell used for gas/nutrient exchange –Some produce a toxin, known as domoic acid, that can accumulate in the tissues or organisms that eat diatoms such as shellfish and small fish –Larger organisms that eat these shellfish or small fish can become ill or die from this accumulated toxin

6. Diatoms Diatoms Diatoms –Mainly reproduce by cellular division (a form of asexual reproduction) –In this type of reproduction, the cell divides and each result cell gets one-half of the frustule. –This cell now must secrete the other half of the frustule (smaller piece) –Due to this, diatoms get smaller each time they reproduce –To restore normal size, they must either sexual reproduce or cast off the frustule and secrete an entire new frustule

8. Dinoflagellates Dinoflagellates Dinoflagellates –Most species live in marine environment –Mostly photosynthetic, some can ingest particles –Each species has unique shape reinforced by plates of cellulose –Two flagella in grooves on body that produce motion –Also reproduce by cellular division –Some are bioluminescent (read “Bay of Fire” on pg. 96)

9. Dinoflagellates Dinoflagellates Dinoflagellates –Zooxanthellae are important dinoflagellates that live in a symbiotic relationship with corals, sea anemones and other organisms (many of these host organisms have little or no growth without their symbiotic partner)

10. Algal Blooms Diatoms and dinoflagellates can go through periods of rapid growth known as “blooms” Diatoms and dinoflagellates can go through periods of rapid growth known as “blooms” This is a result of high levels of nutrients in the water This is a result of high levels of nutrients in the water These blooms can be harmful to marine organisms and even people at times These blooms can be harmful to marine organisms and even people at times

11. Protists Dinoflagellates Dinoflagellates –A few species lack chloroplasts and live as parasites in marine organisms –Some species can reproduce in larger numbers and produce “Red Tide” (read “Red Tides and Harmful Algal Blooms, pg. 338) –Pfiesteria is a dinoflagellate that produces very serious toxins that can cause massive fish kills, harm shellfish and impair the nervous system in humans. –Pfiesteria was discovered near the Outer Banks in North Carolina

12. Protists A few more species of phytosynthetic plankton: A few more species of phytosynthetic plankton: –Silicoflagellates Star-shaped internal skeleton of silica Star-shaped internal skeleton of silica Two flagella of varying lengths Two flagella of varying lengths –Coccolithophores Ornate shells of calcium carbonate Ornate shells of calcium carbonate

13. Protozoa Foraminiferans (forams) Foraminiferans (forams) –Exclusively found in marine community –Found on sandy or rocky bottoms –Shells of calcium carbonate –Can be important contributors of calcareous material on coral reefs or sandy beaches –Pseudopods (false feet) extend through pores in the shell where they are used to capture minute food particles such as phytoplankton

15. Protozoa Radiolarians Radiolarians –Planktonic, mostly microscopic, although a few can reach large sizes –Shell of silica –Like forams, they use pseudopods that extend through pores in the shell where they are used to capture minute food particles such as phytoplankton

17. Protozoa Ciliates Ciliates –Cilia present for locomotion –Most live as solitary cells –Some build shells made of organic debris –May live on hard substrate –Some are planktonic

19. Most Important Characteristics of Marine Microbes

20. Marine Algae Marine algae are important primary producers (photosynthetic) Marine algae are important primary producers (photosynthetic) These algae are called by a generic term “seaweeds” or more formal term macroalgae These algae are called by a generic term “seaweeds” or more formal term macroalgae While some are thought to be the pre- cursors of plants, algae do not have the same advanced structures seen in plants such as roots, stems and leaves While some are thought to be the pre- cursors of plants, algae do not have the same advanced structures seen in plants such as roots, stems and leaves

21. Marine Algae The body of a macroalgae is known as a thallus. The body of a macroalgae is known as a thallus. This thallus can be simple or more advanced in its structure. This thallus can be simple or more advanced in its structure. In some algae, there are: In some algae, there are: –Blades – leaf-like structures –Stipes – stem-like structures –Holdfast – root-like structures (these structures lack the advanced conducting tissues seen in true plants)

22. Marine Algae Some algae also possess pneumatocysts, gas-filled bladders used to keep the blades near the water’s surface where more light is available for photosynthesis Some algae also possess pneumatocysts, gas-filled bladders used to keep the blades near the water’s surface where more light is available for photosynthesis The blades, stipes and pneumatocysts of the giant kelp ( a brown algae) are shown in Fig. 6.8 The blades, stipes and pneumatocysts of the giant kelp ( a brown algae) are shown in Fig. 6.8

24. Marine Algae Many algae also reproduce asexually by a means called vegetative growth. Many algae also reproduce asexually by a means called vegetative growth. In this process, an algae reproduces new individuals that are genetically identical to the parent algae. In this process, an algae reproduces new individuals that are genetically identical to the parent algae.

25. Marine Algae Some algae are commercially important as food (ex: think of the algae used in the sushi industry) Some algae are commercially important as food (ex: think of the algae used in the sushi industry) Other algae are commercially important because of extracts that are harvested from them Other algae are commercially important because of extracts that are harvested from them For example, algin is an extract of brown algae that is used as a emulsifier in dairy products such as ice cream and cheese. For example, algin is an extract of brown algae that is used as a emulsifier in dairy products such as ice cream and cheese.

26. Marine Algae Another example is the carrageenan harvested from red algae. Another example is the carrageenan harvested from red algae. Carrageenan is also used as a thickening agent in dairy products such as yogurt, milkshakes, etc. Carrageenan is also used as a thickening agent in dairy products such as yogurt, milkshakes, etc. Agar is a second extract from red algae. Agar is used to culture microbes in the health care industry. It is also used as a thickener in foods, used as a filler in pharmaceuticals and cosmetics and to protect canned meats (ever opened a canned ham and noticed the “gel” around it? That’s agar.) Agar is a second extract from red algae. Agar is used to culture microbes in the health care industry. It is also used as a thickener in foods, used as a filler in pharmaceuticals and cosmetics and to protect canned meats (ever opened a canned ham and noticed the “gel” around it? That’s agar.)

27. Types of Marine Algae Brown algae Brown algae –~ 1500 species, almost all marine –Some microscopic, most larger - to 300+ feet –Prefer shallow, cold waters –Contain chlorophyll A and C and fucoxanthin –Typical body of holdfast, stipe and blades –Source of algin –Examples: kelp, Fucus, Sargassum

28. Types of Marine Algae Green algae Green algae –Thought to be ancestor of land plants –~ 7000 species; less than 1000 are marine –Found worldwide in wet environments –Microscopic to macroscopic –Some coralline (produce calcium carbonate, Ex: Halimeda) –Chlorophylls A and B as well as carotenoids (same as in true plants) –Store excess energy as starch (same as in true plants) –Cellulose in cell walls (same as in true plants)

29. Types of Marine Algae Notable brown algae: Notable brown algae: –The kelps found in temperate and polar locations are the largest of the algaes –In some species, like the giant kelp, each individual can be hundreds of feet in length –This growth provides habitat for countless species of fish, marine mammals, birds and invertebrates – this community is known as the kelp forest. –Kelp forests are among the most productive (and important) marine habitats.

30. Types of Marine Algae Notable brown algae: Notable brown algae: –Sargassum is a species of brown algae found in the Atlantic between North America and Europe as well as the Gulf of Mexico –Massive floating mats of Sargassum provide habitat for countless species of fish, marine mammals, birds and invertebrates. –This community is known as the Sargasso Sea. –Like the kelp forests, the importance of this community cannot be overstated.

31. Types of Marine Algae Red Algae Red Algae –~ 4000 species, almost all marine –Prefer deep cold waters or warm, shallow waters depending on species –Some are corraline (produce calcium carbonate, Ex: Corallina, shown in Fig. 6.10, pg. 108) –Mostly marine –Contains photosynetic pigments, chlorophyll A and phycobilins

33. Advanced Primary Producers- Plants Seagrasses Seagrasses –Seagrasses are known to exhibit rapid growth and provide food to many organisms –They also provide habitat for countless organisms that hide among the blades in seagrass beds (large collections of seagrass plants) –Eelgrass is the most widely distributed of the seagrasses where it is widely distributed in shallow water bays and estuaries.

35. Most Important Characteristics of Seaweeds and Marine Plants