Chapter 5 The Microbial World

Microbial World Primary producers Very important in the ocean’s ecosystems!

Prokaryotes Oldest forms of life cell wall, cell membrane, no nucleus, ribosomes are different Divided into 2 Domains Bacteria and Archaea As different from each other as they are from humans

Domain Bacteria Branched early Variation based on Evolved great range of abilities Variation based on Shape Cell wall Movement Nutrition

Role of Bacteria Negative Positive Spoil fish and shellfish catches Disease in animals and humans Decay Bacteria Live in detritus Dead organic matter Break down waste and release nutrients into environment Food for animals Degrading pollutants Oil and other toxins Pelagibacter ubique High numbers in open waters Found in sediment 300m under the sea floor

Cyanobacteria First Photosynthetic bacteria Widely spread Polar bear hair Endolithic: burrow into calcareous rocks and coral skeletons Form thick crusts along coasts Exploit oxygen-poor sediments Planktonic: surface Rapidly multiply Cause a Red tide Epiphytes: live on algae or plants Endophytes: live inside algae First Photosynthetic bacteria Chlorophyll a Phycocyanin (bluish) Phycoerythrin (reddish) Produced oxygen as a waste product Stromatolites: mounds formed by cyano

Domain Archaea Look very similar to oldest fossils First found in extreme environments Extremophiles Not all archaea are extremophiles Common in marine environments

Prokaryote Metabolism Photoautotrophic Chemoautotrophic Chlorophyll : perform photosynthesis on folded membranes Different chlorophyll: produces sulfur instead of oxygen Proteorhodopsin or bacteriorhodopsin: capture light energy and store as ATP Does not make organic compounds Derive energy from chemical compounds Hydrogen sulfide Methanogens Produce methane

Metabolism Heterotrophic Nitrogen Fixation Obtain energy from organic matter by cellular respiration Many are decomposers Aerobic: uses oxygen Anaerobic: does not require oxygen Oxygen can be poisonous Anoxic: sediments that do not have oxygen Convert gaseous nitrogen into ammonium Nitrogen can then be used by plants or algae

Unicellular Algae Kingdom Protista

Algae Photosynthesis takes place in chloroplasts Lack flowers, true leaves, stems, and roots Simple cells and reproduction Some have flagella Some are multicelluar, like seaweeds

Diatoms Unicellular with glass-like cell wall Contains silica; same mineral that makes up glass Variety of shapes Contain chlorophyll and other pigments Store food as oil; float to surface for photosynthesis When they die, glass walls accumulate and fossilize Sediments called diatomaceous earth Used as filter material, grinding and polishing, toothpaste

Dinoflagellates dinoflagellates: unicellular, mostly photosyn., cell walls of cellulose, 2 flagella Both fresh and salt Reproduce by simple cell division plankton: communities of organisms that drift near the surface

Red Tide Large number of dinoflagellates that turn coastal marine waters pinkish-orange Produce toxins that kill fish Can be deadly to humans that eat the shellfish

Bioluminescence Ability to produce light

Other Algae Silicoflagellates: Coccolithophorids Cryptophytes Star-shaped internal skeleton and 2 flagella Coccolithophorids Flagellated, spherical cells with button-like strcutures Cryptophytes 2 flagella and lack a skeleton

Protozoans Kingdom Protista

Protozoans Protozoans; animal-like Eat bacteria, other protists, non-living organic matter Lack cell wall Live in most aquatic environments & some in body fluids Classified by movement

Foraminiferans forams: marine protozoans with porous shells made of organic material and calcium carbonate Extends pseudopodia through pores Forms limestone by build up of shells in sediment

Radiolarians Planktonic protozoans that have shells of silica Shells are usually spherical with radiating spines Use pseudopodia Remains create radiolarian ooze

Ciliates Ciliates: diverse group of protists named for the hair-like projections called cilia to move and feed Cilia are shorter and more numerous than flagella and are arranged in rows or clusters Paramecium - free-living pond water organism Tintinnids: drift in water and build vase-like cases Loricas: loose fitting shells that drift

Kingdom Fungi Cannot perform photosynthesis 500 known marine species Mostly microscopic Decomposers Mangrove leaves Some are parasites Lichen