a q u a t ic [aekwatik] adj.
If a plant or animal is aquatic, it lives or grows in water.
—►The dolphin is an aquatic mammal.
biosphere [baiasfiar] n.
The biosphere is the earth’s surface and atmosphere where there are living things.
-> Birds, trees, and worms all thrive in the biosphere.
bizarre [bizar] adj.
When something is bizarre, it is very strange.
—*My bizarre dreams make no sense to me when I am awake.
C e l s i u s [selsias] n.
Celsius is a scale for measuring temperature.
—►Water freezes at zero degrees Celsius.
coarse [koxs] adj.
If something is coarse, that means it has a rough texture.
—►The coarse sweater made my skin itch.
companion [kampaenjan] n.
A companion is a person that someone spends a lot of time with.
-* I always walk to school with my companion Frank.
digest [diciest] v.
To digest means to swallow food and pass it through the body.
—>Allow some time for food to be digested before going swimming.
duration [d/uareijan] n.
The duration of an event is the time during which it happens.
—►The girls watched television for the duration of the evening.
ecology [i:kalad3 i] n.
Ecology is the study of the environment and living things.
-* We study ecology to learn how to help improve the Earth.
feat [fi:t] n.
A feat is an impressive or difficult achievement or action.
—»The elephant’s standing up on one leg was a feat.
3infinite [infanit] adj.
If something is infinite, it has no limit or end.
-* Many scientists believe that the universe is infinite.
nucleus [ry’uiklias] n.
The nucleus is the central part of an atom or cell.
-* The nucleus is made up of many tiny particles.
parasite [paerasait] n.
A parasite is a tiny animal or plant that attaches to another animal to get food.
—»The sick dog was covered in parasites.
prominent [prdmanant] adj.
When something is prominent, it is important and well known.
—►Queen Victoria was a prominent person in history.
repetitive [ripetativ] adj.
When something is repetitive, it is repeated many times and becomes boring.
—►Working on an assembly line making cars every day is a repetitive job.
reproductive [ri:pradAktiv] adj.
If something is reproductive, it has to do with a living thing producing young.
—►The reproductive system of a plant is simple.
temperate [tempsrit] adj.
When a place is temperate, it never gets too hot or cold.
-* In Peru, the weather is temperate and rarely gets too hot or cold.
t o le r a n c e [tdlarans] n.
Tolerance is the ability to accept something painful or unpleasant.
—►Boxers have a high tolerance for pain.
undergo [Andargou] v.
To undergo an action means to have it happen to you.
-» The cancer patient undergoes treatments twice a week.
vulnerable [vAlnerabal] adj.
When someone is vulnerable, they are weak and without protection.
—»He felt very


Small World
Even though people can’t see me, I’m an important part of Earth’s biosphere. Scientists
who study ecology know that I was the first life form on Earth. There is more of my kind than
any other plant or animal in the world. Without me, other plants and animals would not even
exist, l ama protist, and my tiny body is made up of one single cell.
In my small world, things can be absolutely bizarre. Unlike most aquatic plants and
animals, I don’t need a temperate climate. I have a very high tolerance for extreme
conditions. Right now, I’m swimming around in a bucket of boiling water! The temperature
is 150 degrees Celsius, but I feel comfortable. I have coarse hairs called cilia that help me
swim around in here. I move my cilia in a repetitive motion for the duration of my swim. I
cannot go very fast, though. It takes me about five minutes to swim a distance of just one
millimeter!
When I get hungry, I look for tiny, vulnerable parasites. I swim up to one and swallow it
whole. I digest things much like people do. I have an organ that works just like a human
stomach. After I eat, I release nitrogen gas. Nitrogen is a prominent gas in the earth’s
atmosphere. Other plants and animals need my nitrogen to survive.
My reproductive ability is my most unique trait. I don’t need a companion to mate with.
Instead, I undergo a process called fission, where my own nucleus splits in half. An exact
copy of my nucleus is made, which forms into another protist. It really is an impressive feat.
I can create an infinite number of new protists all by myself!