10 Reading: Protists
The goal of this exercise is to learn about the protists. We will study major groups and for most of the groups, we will study representative genera.
Procedure
For each specimen:
- Read the information thoroughly.
- Create notes. Your notes will be most helpful if they include a drawing, a description, and significant information such as life cycle, commercial value, ecological significance, and unusual characteristics.
Euglenozoans
Kinetoplastids
Kinetoplastids are flagellated and unicellular. They have a dark staining region of mitochondria called a kinetoplast.
Some kinetoplastids have symbiotic (close) relationships with other organisms. Trypanosomes are Kinetoplastids that cause African sleeping sickness. They are transmitted to their human hosts by the bite of a tsetse fly. Trypanosoma causes African sleeping sickness.
Euglena
Euglena are unicellular. Many Euglenids feed by phagocytosis. Many species of Euglenids are photosynthetic but can become heterotrophic when sunlight is unavailable (mixotrophs).
Euglena use flagella for moving. The outer covering called a pellicle, is flexible and assists in moving. Some have an eyespot with a photoreceptor that is capable of detecting the presence of light. Reproduction is asexual.
Diatoms
Diatoms are the most numerous unicellular algae in the oceans and as such are an important source of food and oxygen. They are also important in freshwater environments. They capture 20 to 25% of solar energy captured by living organisms. The cell walls of diatoms contain silica (a component of glass) and are formed in 2 halves like a pillbox. Their remains form diatomaceous earth. It is used for filtering agents and abrasives such as scouring powders. Diatoms are a major component of phytoplankton in freshwater and marine environments.
Brown Algae
Brown algae are autotrophs (photosynthetic). Their characteristic brown color is due to carotenoid pigments. They are multicellular and range in size from small to very large. Some are 50 m to 100 m long. They are often found along rocky shores in temperate climates. The body (thallus) contains holdfasts for attachment, blades, and a stem-like structure that holds the blades is called a stipe. Many species have floats that function in floatation. Some have gas-filled floats. Mucilaginous (slimy) material in the cell walls retards drying in exposed individuals when the tide goes out. Most species have a life cycle with alternation of generations.
Fucus
Fucus is a common “seaweed” found along the rocky coast. Some species of Fucus have diploid adults.
Macrocystis and Nereocystis
Macrocystis and nereocystis are deep-water kelps.
Sargassam
Sargassam sometimes breaks off to form floating masses. Other marine organisms congregate around these masses.
Laminaria
Laminaria is a brown alga that is usually found attached just below the intertidal zone. It has a life cycle with alternation of generations.
Dinoflagellates
Protective cellulose plates cover dinofl