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Microorganisms – Protists: Euglena
Euglena are unicellular organisms classified into the
Kingdom Protista, and the Phylum Euglenophyta. All
euglena have chloroplasts and can make their own food by
photosynthesis. They are not completely autotrophic
though, euglena can also absorb food from their
environment. Euglena usually live in quiet ponds or
puddles.
Euglena move by a flagellum (plural flagella), which is a long whip-like structure that acts like a
little motor. The flagellum is located on the anterior (front) end, and twirls in such a way as to
pull the cell through the water. It is attached at an inward pocket called the reservoir.
Color and label the reservoir grey.
Color and label the flagellum black.
The Euglena is unique in that it is both heterotrophic (must consume food) and autotrophic (can
make its own food). Chloroplasts within the euglena trap sunlight that is used for
photosynthesis and can be seen as several rod-like structures throughout the cell.
Color and label the chloroplasts green.
Euglena also have an eyespot at the anterior end that detects light, it can be seen near the
reservoir. This helps the euglena find bright areas to gather sunlight to make their food.
Color and label the eyespot red.
Euglena can also gain nutrients by absorbing them across their cell membrane, hence they
become heterotrophic when light is not available, and they cannot photosynthesize.
The euglena has a stiff pellicle outside the cell membrane that helps it keep its shape, though
the pellicle is somewhat flexible, and some euglena can be observed scrunching up and moving in
an inchworm type fashion.
Color and label the pellicle blue.
In the center of the cell is the nucleus, which contains the cell’s DNA and controls the cell’s
activities. The nucleolus, which makes ribosomes, can be seen within the nucleus.
Color and label the nucleus purple.
Color and label the nucleolus pink.
