Leanna Harvey, age 11, of Lethbridge, Alberta, Canada, for her question:
Do you call a euglena a plant or an animal?
Anybody knows the difference between a lion and a dandelion and most of us assume that we can distinguish between all the other plants and animals. The euglena, however, is a highly controversial figure on a miniature scale. This microscopic organism can be called a plant and also an animal.
Sorting the larger plants and animals is no problem. But sometimes it is just about impossible to judge whether a microscopic single celled organism is a plant or an animal. In most cases, the problem can be settled with a couple of simple questions. Can it move? If the answer is yes, chances are it is an animal of the Phylum Protozoa. Can it use sunlight to manufacture its own food? If the answer is yes, almost cer¬tainly it is a plant.
However, this simple little questionnaire breaks down when we submit it to the simple little euglena. The answer to both questions is yes. Yes, the peppy midget can move around and yes, it can use sunlight to manufacture its own food. The an¬swers can be verified under a microscope. When magnified, we see the whip like fla¬gellum it waves to propel itself through its freshwater pond. Chances are, we see that its elongated body is stuffed with green chlorophyll. And chlorophyll is the magic substance that plants, and only plants use to mate their food.
Biologists strive to classify every living thing in its proper group. One might expect that they took a firm stand on the euglena and classed it as plant or animal ¬once and for all. However, the question was never settled because Mother Nature her¬self was undecided. The euglena has the qualifying features of both a plant And ani¬mal and nobody can say that it is neither.
As we know, plant and animal classifications are tagged with handsome scientific names. The euglena has a double set of fancy scientific names because it is classified in both the plant kingdom and the animal kingdom. It is listed in the plant phylum Euglenaphyta and also in the animal phylum Protozoa. In the plant world, we find it in the Order Euglenales under the family name Euglenaceae. About 150 individual species are grouped in the genus Euglena.
In the animal kingdom we find the euglena in the Order Euglenoidena, under the family name Euglenidae. The genus name Euglena has the sae name, whether we classify the various euglenas as animals or plants.
Its plant and animal qualities dive the euglena all sorts of survival advantages. In sunlit water, it uses green chlorophyll to create its basic food. In the dark, it absorbs liquid nutrients through its skin. And when times are bad, it can change its location. As it swims, the tiny body squeezes and stretches while the flagellum waves with all its might. And the traveling euglena appears to be moving backward, frantically following its tail.