Is the Euglena plant or animal? Or is it something else? The year is 2019. I am seventy-one. Yet I recall my school days and my sophomore year high school biology. One day the teacher, Miss Warne, discussed a single cell creature with her class. It has a whip like thread called a flagellum. That creature is the euglena.
The flagellum pulls rather than pushes the euglena through the water. Such locomotion is at least suggestive that euglena is an animal. Yet, the euglena has chloroplasts like a plant.
Euglena Plant or Animal?
While it has chloroplasts like a plant, the euglena lacks another characteristic of plants, a cellulose wall. It feeds in animal fashion, but it also produces sugar like a plant does. It has a light-sensitive area called an eyespot. Because it resembles both animals and plants, scientists have resisted categorizing euglena as either one. Was a final decision made? Well yes there was. What decision do you think they made?
The Decision: Don’t Decide
Nearly sixty years later has modern science confidently relegated the euglena to an appropriate place in the scheme of things? A “no” answer might seem the coward’s way out. Yet scientists have conveniently added another kingdom.
The new kingdom classification is Protista. Other single celled organisms have been assigned to that kingdom. Among them are the ameba and the paramecium. In the opinion of this scientist, there are only two valid kingdoms to choose from, the animal kingdom and the plant kingdom. Of the two, the choice should be: euglena is an animal.
One final thing: even if assignment to another kingdom possesses validity, even if… Is there reason to say a member of that kingdom can change kingdoms, say to become a plant or an animal?
Note: You might also enjoy Are They Alive? DNA, Viruses, Gametes
- Fairfax County Public Schools: Euglena – Euglena gracilis
- Johnson County Community College (Kansas): Euglena’s Homepage