Imagine yourself at a picnic in a park. It is a beautiful day, and everything is just great! You lay out your food, build a fire, and start roasting your hot dogs. Then, suddenly, the wind starts blowing, the sky gets cloudy, lightning flashes, thunder rolls, and rain starts pouring down. You, your food, and your fire, all start to get wet. What are you going to do?
Well, you have some choices:
You could do nothing, in which case, your food will get soaked, your fire will go out, and you will get cold and wet and probably hungry. You might even be struck by lightning!
You could put on a big raincoat or put up a tarp to keep yourself, your food, and your fire dry while you finish your picnic. (Of course, you will still have to keep an eye on that pesky lightning.)
You could pick up your stuff, go under a park shelter, and use the gas burners to cook your food and finish your picnic.
You could just go home and have an indoor picnic.
If you choose to change...
Yourself by putting on a raincoat;
Your behavior by using a gas fire under a shelter rather than a wood fire out in the open; or
Your location by going home,
...you will be changing or adapting to the changing weather so that you can continue to enjoy your picnic.
On the other hand, if you choose to do nothing to adapt to the changing conditions, you will probably make yourself miserable, prevent yourself from finishing your picnic, and you might even make yourself extinct!
When you started your picnic, you had the right clothes and equipment for a sunny day at the park. You were "fitted" or "adapted" to the environment as it then existed. Similarly, plants and animals are adapted to the environments in which they live. Their individual adaptations permit them to get the food, water, and shelter they need to live. For example, sharks have fins, streamlined bodies, and sharp teeth that enable them to swim quickly and catch food in the ocean. Trees have leaves to catch sunlight and roots to collect water and nutrients from soil on land. Sharks cannot live on land and trees cannot live in the ocean because they are not adapted to those environments. Photos © 2000-www.arttoday.com
But environments change. Just as your picnic environment changed when the cloudburst came, environments around the world change over time. And as environments change, the plants and animals living in them must change and adapt to the new conditions. They must change the shape and function of their bodies (physical adaptation), or they must change their behavior (behavioral adaptation), or they must move to a different place that has the environment they need. Otherwise, they too become uncomfortable and possibly extinct!