Euglena, the Mystery Creature
Sometimes scientists have trouble deciding whether something is a plant
or an animal. Whenever they see a Euglena, they are puzzled all over
again as you may have been.
Usually, telling a plant from an animal isn‟t difficult at all. Long ago,
scientists separated plants and animals into two separate kingdoms.
Members of the animal kingdom move from place to place by
themselves, and they must eat plants or other animals to survive. On the
other hand, members of the plant kingdom cannot move very much on
their own, but they make their own food. Chlorophyll, the little particles
that give plants their green color, lets the plant use water and carbon
dioxide gas to make sugar (glucose) for food.
Euglena began causing problems for scientists long ago. It is a tiny
creature that lives in pond water and swamps and can only be seen with a
microscope. Its whole body is made up of one cell, and it is shaped a little
like a hotdog. Inside the tiny cells are grains of chlorophyll just like the
chlorophyll in green plants, but Euglena also has a mouth and a gullet (a
kind of stomach), and it can eat smaller plants and animals.
Like many one-celled animals, Euglena swims through the water by
quickly moving a long tail, called a flagellum, from side to side. Around
its mouth, cilia, which look like lots of tiny hairs, wave back and forth to
draw food into the gullet. Strangest of all, this creature has an “eye”, a red
spot near the flagellum that scientists say can tell light from dark.
Is Euglena a plant or an animal? Biologists, scientists who study living
things, are not sure. Some think that it began as an animal that somehow
absorbed some chlorophyll. Others think that it was always a plant. While
bacteria are an example of one-celled prokaryotes, most once-celled
Eukaryotes are either algae, which are plants, or protozoa, which are
animals. Euglena has decided to be both plant and animal. Perhaps one
day someone will discover other creatures like Euglena, forcing scientists
to create a whole new kingdom just for them. Until then, this strange
creature will remain a scientific mystery.
Now that you’ve seen Euglena and have read more about it, what do you
think it is? Why?
Euglena, the Mystery Creature SCAN the story to
ANSWER these questions...
What kind of scientists study Euglena?
Why are they puzzled by this creature?
What plant-like characteristics does the Euglena have?
What animal-like characteristics does the Euglena have?
Where does Euglena live?
Do you think scientists will ever discover other creatures like Euglena?
PLACE the correct word in the blank.
Animal Kingdom Plant Kingdom Flagellum
Chlorophyll Biologists Algae Protozoa
a. scientists who study living things
b. members cannot move very
much on their own
c. gives plants their green color –
used in photosynthesis
d. one-celled animals
e. a long tail
f. members move from place to
place by themselves
g. one-celled plants