"Ecology" is the study of how living creatures relate to one another within their environment. It includes all the processes that promote the continuation of life and the preservation of the environment.
The ecology of a specific area is known as an "ecosystem." Everything within the ecosystem is interdependent. If one part of the ecosystem is damaged, all the other elements of the ecosystem will be affected. Living things in an ecosystem are known as "biotic," and non-living things such as air and sunlight are known as "abiotic." A balanced ecosystem is capable of reproduction and can sustain itself.
An "organism" is a single living thing. A group of similar organisms that are able to mate and reproduce are referred to as a "species." The number of individuals in a particular ecosystem is the "population" of that species.
A "habitat" is the environment that an organism needs in order to live, grow, and reproduce. The "carrying capacity" of the ecosystem is the number of organisms that the available resources will support. A "limiting factor" in an ecosystem is the quantity of a particular resource available to the organisms that limits the population, such as the amount of water in a pond. "Competition" exists between organisms or species as they compete for limited amounts of the same resources.
"Adaptations" are the changes that organisms make to allow them to deal with changes in the environment. The desert-dwelling kangaroo rat, for example, doesn’t need to drink water because it gets moisture from the seeds and plant material it eats.
Within an ecosystem there are a variety of relationships that occur. There are "predators," animals that hunt other animals, and "prey," the targets of the hunters. There are "parasites," organisms that live on other organisms and eventually kill them. There are "mutual" relationships where both organisms benefit. A good example is a cleaner fish in the ocean. The cleaner fish removes algae and debris from the scales of larger fish; the larger fish stays healthy and the cleaner fish eats the algae and other materials it cleans off.
A "food chain" is a way of looking at how energy moves through an ecosystem. The process starts with "photosynthesis," the ability of plants to absorb sunlight and carbon dioxide and convert it to energy while releasing oxygen. Animals feed on the plants, larger animals feed on the smaller animals, and even the larger animals feed the process when they die and are eaten by scavengers or decompose into food for plant growth.
"Sustainability" is a system's ability to endure over time. In a sense, the whole earth is a giant ecosystem, and the better we maintain its balance, the better it will sustain itself into the future.