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MARINE MICROBES
Chapter Outline
MARINE VIRUSES
Viral Characteristics
MARINE BACTERIA
General Characteristics
Nutritional Types
Cyanobacteria
Other Photosynthetic Bacteria
Chemosynthetic Bacteria
Heterotrophic Bacteria
History of Modern Mycology
General Features of Fungi
Diatoms
Other Ochrophytes
Labyrinthomorphs
Haptophytes
Alveolates
Dinoflagellates
Ciliates
Chapter Objectives
• Describe the structure and characteristics of viruses.
• Interpret a phylogenetic tree of marine organisms.
• Identify the variety of marine viruses.
• Describe the structure and characteristics of archaea.
• Explain the various methods by which archaea gain nutrition.
• Describe the structure and characteristics of fungi.
Key Terms
microbe
virology
viral replication
nucleocapsid
envelope
icosahedral virus
helical virus
binal virus
lytic cycle
lysis
lysogenic cycle
seston
phycocyanin
chromatic adaptation
photoprotective pigments
consolidation
lithification
sedimentation
marine snow
nitrogen fixation
nitrogenase
heterocyst
nitrification
endosymbiotic theory
yeast
filamentous fungus
hypha
ascus
ascospore
lichen
stramenopiles
mastigonemes
heterokont
ochrophytes
secondary plastid
endosymbiosis
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alveolus
pellicle
dinoflagellate
dinosporin
cingulum
sulcus
ciliates
membranelles
cytostome
micronucleus
macronucleus
conjugation
amnesic shellfish
poisoning
microvillus
pseudopod
foraminiferan
foram
Chapter Summary
1. Viruses are more abundant than other microbes in the sea. Marine planktonic viruses
are icosahedral and lytic, and are responsible for the death of many bacteria and
2. Bacteria have cells with a simple, prokaryotic organization. Chemosynthetic and
photosynthetic bacteria extract inorganic nutrients, such as nitrogen, phosphorus,
4. Marine fungi are microscopic decomposers and pathogens. Most are sac fungi that
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5. In marine environments, nonfungal eukaryotes make up a large portion of the
plankton and benthos. Dinoflagellates, diatoms, coccolithophores, and
6. The eukaryotic groups are distinguished by their cell coverings; the structure of their
cell membranes; their possession of cilia, flagella, and pseudopods of various shapes
Chapter Outline
I. Marine Viruses
A. Microbes: organisms not visible with the naked eye.
B. Virology: study of viruses.
C. Viral characteristics.
1. Viral replication.
2. Viral structure.
a. Virion.
b. Capsid.
3. Viral life cycle.
a. Lytic cycle.
b. Lysogenic cycle.
D. Biodiversity and distribution of marine viruses.
E. Ecology of marine viruses.
1. Control populations in plankton communities.
II. Marine Bacteria
A. General characteristics.
1. Prokaryotic cells.
2. Reproduce asexually by binary fission.
B. Nutritional types.
1. Osmotrophy.
2. Exoenzymes.
3. Nitrogen fixation.
4. Cyanobacteria.
a. Photosynthetic organisms; store excess sugar as cyanophycean starch.
5. Other photosynthetic bacteria.
6. Chemosynthetic bacteria.
7. Heterotrophic bacteria.
a. Consolidation.
d. Marine snow.
C. Nitrogen fixation and nitrification.
1. Nitrogenase.
2. Heterocyst.
3. Nitrification.
D. Symbiotic bacteria.
3. Photophores.
III. Archaea: Prokaryotic with a Cell Wall, but Composition Is Different than Eubacterial Cell
Walls
A. General characteristics.
B. Nutritional types.
C. Hyperthermophiles.
IV. Eukarya
A. Fungi.
3. Mycology.
4. General features of fungi.
a. Four groups of fungi.
5. Ecology and physiology of marine fungi.
a. Obligate marine fungi require brackish or ocean water to grow and
reproduce.
b. Marine fungi are classified as a function of the substrate on which they grow.
6. Reproduction of marine fungi.
a. Budding.
7. Maritime lichens.
B. Stramenopiles.
1. All members have two different forms of flagella (heterokont).
2. All members have a flagellated phase of the life cycle, although it is abbreviated in
some organisms.
5. Diatoms.
a. Frustule.
b. Valve.
6. Other ochrophytes.
a. Silicoflagellates.
b. Labyrinthomorphs.
i. Zoospores.
a. Dinosporin.
3. Ciliates.
a. Membranelles.
b. Cytostome.
E. Choanoflagellates.
F. Amoeboid protozoans.
1. Pseudopod.
Suggestions for Presenting the Material
1. It is difficult for students to get excited about marine microbes and protists. Students
are less familiar with microbes and protists than animals, owing to the lack of
2. There are many video clips and websites that can be used in lecture or for web-based
3. In the Blue Planet series, ”Coral Seas,” there is a short video clip of the dinoflagellate
4. Summarize the organization of groups using a compare-contrast table for the
students to complete. Then ask them to find digital photos online to add to their
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Classroom Discussion Ideas
1. Describe the process of energy production for photosynthetic, chemosynthetic, and
heterotrophic bacteria. What is the advantage of each type of energy production?
Videos, Animations, and Websites
Videos
Into the Abyss. (PBS, 1998)
This program explores some of the unusual life forms that survive by black smoker
Cool Classroom—Microbial Loop.
Websites
Census of Marine Life.
American Society of Microbiology.
A source of the document listed above by Hunter-Cevera and colleagues (2005).
University of Calgary, Dinoflagellates Page.
Information on the general biology of dinoflagellates and red tides, with images and
University of Indiana, Diatom Page.
Information on diatoms and the scientists who study them, with numerous links to other
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The American Society for Microbiology.
General information and graphics about viruses, bacteria, archaeons, and eukaryotic
University College London, MIRACLE Project.
Detailed information on the biology and study of radiolarians, including many images.
University of California Museum of Paleontology, Tree of Life.
Brief descriptions and some images of archaeons. The homepage provides access to
Brief descriptions and some images of forams.
Brief descriptions and some images of radiolarians.
Suggested Answers to End of Chapter Questions
Multiple Choice
1. b. bacteriophages
2. d. phagocytosis
Matching
1. c.
2. e.
Chapter 6 69
1. f.
2. c.
Short Answer
1. What biotic and abiotic factors control viral activity in plankton?
Viruses can be inactivated by biological mechanisms (such as enzymes secreted
2. Why are archaeons called “extremophiles”?
Archaeons are sometimes referred to as extremophiles because they can live in
3. Describe how marine bacteria hasten the fall of dead particles from surface waters.
As an organic particle sinks in the water column, it is colonized and modified by
4. Explain why the calcareous skeletons of forams and coccolithophores do not
accumulate at the greatest depths of the sea.
Calcium carbonate frequently precipitates in shallow seas, but at great depth
70 Marine Microbes
5. How do the cells of diatoms and dinoflagellates differ?
Diatom cells are surrounded by two siliceous frustules, one half larger than the
6. What significant role do heterotrophic bacteria, fungi, and labyrinthomorphs play
in marine habitats?
Many heterotrophic bacteria, fungi, and labyrinthomorphs (fungal-like protists)
7. Describe the methods of food capture by tintinnids, foraminiferans, and
choanoflagellates.
Tintinnids capture food by suspension feeding with their membranelles.
Foraminiferans are amoeboid protozoans, having branched pseudopods that
Thinking Critically
1. If planktonic viruses lyse bacterial cells at a high rate, what effect might this have on
food webs in the pelagic zone?
Since lysis causes bacterial cell death, there would be fewer bacteria in pelagic
2. Many planktonic microbes have projections of some sort from their cells, cell walls,
tests, and loricas. What are the possible advantages of these structures?
Cellular projections increase the surface area to volume ratio, an adaptation to life
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3. Marine microbes exhibit a wide range of sizes. If you wanted to study them, what
methods would you use and what problems might you encounter in trying to collect
them from seawater?
Different plankton nets can be used to collect protists; the size of the collected
4. In what ways is Prochlorococcus better adapted for life in the open tropical seas than
diatoms?
Prochlorococcus cells are much smaller than diatom cells; the surface area to volume
Suggested InfoTrac® Articles
“A Plentitude of Ocean Life.” DeLong, E.F. Natural History, (2003).