Observing Live Algae with a Microscope

Materials (Live Specimens):

Observe the Euglena

Euglena is a genus of single-celled organisms that live in fresh water, such as ponds or lakes. These organisms are known for their unique characteristics, as they possess both plant-like and animal-like features.

They are typically elongated, spindle-shaped organisms, ranging in size from about 15 to 500 micrometers.
A distinguishing feature of Euglena is the presence of a long whip-like tail called a flagellum, which they use for movement through water.
They have a flexible outer covering called a pellicle, providing structural support and allowing them to change shape.
Euglena are unique as they can perform photosynthesis like plants and also exhibit behaviors similar to animals.
They possess a primitive eye-spot that helps them detect light, aiding in their movement towards light sources.

Procedure

1. Use the scanning lens to focus the slide. At this point, euglena will appear as small green dots.

Estimate how many you see in your viewing field under this magnification:____

2. Focus using the low power objective. Estimate how many euglena you see now: _____

3. Focus using the high power objective. Estimate how many euglena you see now: _____

4. The microscope's magnification is probably not powerful enough to see the euglena's flagella.
What is the purpose of the flagella? _______________________________

5. The euglena also move by scrunching up or rolling into a ball. This movement is called EUGLENOID MOVEMENT.

Locate a euglena and watch it to see if you can recognize this special type of movement.

6. Darken half your viewing field. You can do this by placing dark paper over the microscope's light, or you can rotate the diaphragm slightly (not clicked into place).

The goal is to have a "half-moon" dark spot on your slide. View the euglena as they interact with this dark area. Describe your observations.

7. Sketch the euglena. LABEL the chloroplasts, cell membrane (pellicle) and the eyespot.

Observe Spirogyra & Volvox

8. View a slide of spirogyra under scanning, low power, and high power. On one filament of spirogyra, estimate how many cells are present: _________________________

9. Sketch the spirogyra. LABEL the chloroplasts and the cell wall.

10. View the volvox under scanning and low power. Sketch the volvox.

Post-Lab Analysis

11. Compare and Contrast each of the 3 Algae you looked at by filling out a Venn Diagram (you should be able to come up with at least 3 items for each group)