This document summarizes key marine microbes found in plankton. It discusses diatoms, dinoflagellates, forams, euglena, and volvox. Diatoms are the most common phytoplankton and have a glassy cell wall and symmetrical shape. Dinoflagellates can cause red tides and some are in a mutualism with corals. Forams have a shell and pseudopod and are an important part of the marine food web. Euglena can photosynthesize or absorb nutrients and reproduce by binary fission. Volvox forms multicellular colonies through asexual reproduction and provides a model for cell regeneration studies.

1. Chapter 6 Marine Microbes
Plankton
(organisms invisible to the naked eye)

2. • 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
microscope
1. Diatoms
2. Dinoflagellates
3. Forams
4. Euglena
5. Volvox

3. 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.

4. Diatom Structure
• Bilaterally symmetrical
• Glassy Cell wall
• 2 valves- 1 large, 1 small
• Visible geometrically shaped pattern-(helps
distinguish between species)

5. Reproduction
• Reproduction: • Digestion:
– Asexually by – Makes own food
fission (autotroph) via
photosynthesis
• When cells divides,
each daughter gets
one of the 2 valves
• Eventually daughter
that inherited smaller
valve will reproduces
sexually

7. • Level of organization:
– Unicellular and
eukaryotic
• Ecological Role
– Responsible for ~50% of
oceans energy
production
– Producers

8. Dinoflagellates- structure
• Globular, single-celled
organisms
• 2 flagella that lie in
groves on the center of
surface
• Larger of phytoplankton

9. 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?

10. • 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.

11. Goodby’s Creek in Mandarin during last Algae Bloom

13. 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

14. Foram Reproduction
• Asexual fission most
species
• Sexual reproduction-
some species

15. 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

16. Ecological Role
• Food for fish and invertebrates (inverts)
• Turn over nutrients in the ocean
• Most abundant group of fossils
– Make up sediments

17. • http://www.youtube.com/watch?v=Fpry23bS
6g0&safety_mode=true&persist_safety_mode
=1&safe=active

18. Ever wonder about that green
gunk?
• Its Euglena!
– Possess chlorophyll, 1 or
2 flagella

19. 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

20. Euglena Structure (draw sketch
on back side of Study Guide)

21. Euglena: Ecological Role
• Photosynthesizer
• Acts as food for
other protists and
fish

22. • http://www.youtube.com/watch?v=4MlR3dKf
Xmc&feature=related&safety_mode=true&per
sist_safety_mode=1&safe=active
•

23. 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

24. Volvox Reproduction
Asexual Sexual
• Gonadia near the posterior
– Divide numerous times to
• Male colonies release
produce new colonies sperm into water column
– Genetically identical to the • Female colonies’ individual
parent cells enlarge to become
– Mitosis eggs
• Offspring different from
parents
– Meiosis

25. Volvox Digestion
• Producer
• Makes energy via
photosynthesis

26. Volvox Ecological Role
• Primary producers in
freshwater ecosystems
– Lakes, ponds, ditches
• Model science organism
for cell death and
regrowth
• Some parasites feed off
Volvox

27. Volvox
• http://www.youtube.com/watch?v=He9FSeGR
i3A&safety_mode=true&persist_safety_mode
=1&safe=active

28. 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)