I always get a a little sad every year when school is over with. I guess I just don't like endings very much. I forget sometimes that usually with every ending comes a new beginning, and both are an important part of life.
In fact, there have been many beginnings and endings throughout the history of our planet. There have been many species, like dinosaurs, prehistoric mammals, flying reptiles and the great monsters of the sea who have ruled the earth at one time or another, only to disappear in order to make room for more new and exciting creatures, including us. But there has been at least one form of life that seems to have weathered all of the changes that time has brought. One of the most persistent forms of life on earth was also the earliest ever to appear on the planet: bacteria.
Yuck! I know. With all the hand washing parents "recommend," you'd think the little stinkers wouldn't stand a chance. But not only are bacteria Earth's oldest form of life, dating back 3.5 billion years in the fossil record (Earth is about 4.5 billion years old)--they can survive just about anywhere.
Microbes that thrive in the most extreme conditions of the earth are called extremophiles. Different types of extremophiles are adapted to different harsh environments and are named according to the climate or substance they inhabit.
For example, a hypolith is an organism that lives underneath rocks in the cold, cold Arctic. They generally live under translucent rocks, so that they can receive light from the sun to create their own food source through photosynthesis, which is the process plants use to make sugar from sunlight and carbon dioxide.
A thermophile, on the other hand, likes the hottest jacuzzis on earth: they love to hang out in places like the Grand Prismatic Spring in Yellowstone National Park (where their body chemicals react with heat to produce crazily beautiful colors), or around the blazing hot hydrothermal vents of the ocean.
Planetary scientists from NASA have even dived into volcanic lakes in South America to study extremophiles and other odd life forms that thrive in the harsh conditions there. The volcanic lakes provide not only a chance to study what effects those extreme conditions may have on humans (helping to prepare astronauts for space travel), they give clues as to what life on Mars may have been like 3.5 billion years ago, when scientists say the red planet was covered with icy lakes and rivers. They also let scientists determine what kind of environments existing in the universe today may harbor life forms.
For an interactive exhibit about extremophiles, check out X-treme Microbes from the National Science Foundation.
