Chapter 6 Marine MicrobesPlankton
(organisms invisible to the naked eye)
• Include viruses, one-celled organisms, and fungi.• Microbes play many different roles in marine ecosystem. • Phytoplankton-planktonic algae• Zooplankton-larvae of small animals-ex fish, jellyfish• We will discuss 3 of these in detail that you will be
accountable for and be able to identify under a microscope1. Diatoms2. Dinoflagellates3. Forams4. Euglena5. Volvox
Diatoms Characteristics
• Most distinctive of plankton samples– Most common
• Low latitudes-occur in coastal waters• Phytoplankton-Contributed to most of primary
productivity of an area.
Diatom Structure• Bilaterally symmetrical• Glassy Cell wall• 2 valves- 1 large, 1 small• Visible geometrically shaped pattern-(helps
distinguish between species)
Reproduction• Reproduction: –Asexually by
fission• When cells divides,
each daughter gets one of the 2 valves• Eventually daughter
that inherited smaller valve will reproduces sexually
• Digestion: – Makes own food
(autotroph) via photosynthesis
• Level of organization:– Unicellular and
eukaryotic
• Ecological Role– Responsible for ~50% of
oceans energy production
– Producers
Dinoflagellates- structure
• Globular, single-celled organisms
• 2 flagella that lie in groves on the center of surface
• Larger of phytoplankton
Reproduction
• Asexually by fission– Split cell into two– Can happen at a rate of one division per day
• Sexual in some species by gametes
• If you had two species of Dinoflagellates and species A produced asexually while species B produced sexually, which species to you expect to survive throughout time longer and why?
• Ecological Role: Some species are responsible for Red Tide– algae bloom-large quick
population boom– Produce toxins, usually cannot
eat fish during this time– http://
www.youtube.com/watch?v=auEePWRqj7Y&safety_mode=true&persist_safety_mode=1&safe=active
• Example (back side of Study Guide) Zooxanthellae are collections of dinoflagellates– They lack flagella like most
species– Mutualistic relationships with
corals, jellyfish, and mollusks.
Goodby’s Creek in Mandarin during last Algae Bloom
Forams Characteristics and Structure
• Have a pseudopod-organelle that is an extension of the cell surface– Used for locomotion and food capture
• Have a shell• deep as Marianas Trench• members of zooplankton
Foram Reproduction
• Asexual fission most species
• Sexual reproduction-some species
Forams: digestion/energy
• Consume a lot of diatoms and dinoflagellates
• Some host green/red algae – Symbiotic relationship
• Forams get nutrients • Coral reefs get calcium
carbonate
Ecological Role
• Food for fish and invertebrates (inverts)• Turn over nutrients in the ocean• Most abundant group of fossils– Make up sediments
• http://www.youtube.com/watch?v=Fpry23bS6g0&safety_mode=true&persist_safety_mode=1&safe=active
Ever wonder about that green gunk?
• Its Euglena! – Possess chlorophyll, 1 or
2 flagella
Euglena
• Salt or fresh water • Digestion- perform
photosynthesis or absorb nutrients – stigma at base of flagella
allows euglena to orient themselves towards a light source
• Reproduce using binary fission– Split into two new
organisms
Euglena Structure (draw sketch on back side of Study Guide)
Euglena: Ecological Role
• Photosynthesizer • Acts as food for
other protists and fish
• http://www.youtube.com/watch?v=4MlR3dKfXmc&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
•
Volvox• Structure: – Individual cells form
colonies (level of organization= multicellular) up to 50,000 cells!!!!- cannot live alone
– Eyespots that allow them to swim near light
– Flagellates –locomotion• Similar to Euglena
Volvox ReproductionAsexual• Gonadia near the posterior
– Divide numerous times to produce new colonies
– Genetically identical to the parent
– Mitosis
Sexual
• Male colonies release sperm into water column
• Female colonies’ individual cells enlarge to become eggs
• Offspring different from parents– Meiosis
Volvox Digestion
• Producer• Makes energy via
photosynthesis
Volvox Ecological Role
• Primary producers in freshwater ecosystems– Lakes, ponds, ditches
• Model science organism for cell death and regrowth
• Some parasites feed off Volvox
Volvox
• http://www.youtube.com/watch?v=He9FSeGRi3A&safety_mode=true&persist_safety_mode=1&safe=active
Independent Work Time
• Finish back side of your study guide and turn in.– Study Guides will count as a homework/classwork
assignment for Session 3
• You can find more information in Chapter 6 (blue MARINE BIOLOGY class set books)