A habitat is a place where an organism makes its home. A habitat meets all the environmental conditions an organism needs to survive. For an animal, that means everything it needs to find and gather food, select a mate, and successfully reproduce.
For a plant, a good habitat must provide the right combination of light, air, water, and soil. For example, the prickly pear cactus, which is adapted for sandy soil, dry climates, and bright sunlight, grows well in desert areas like the Sonoran Desert in northwest Mexico. It would not thrive in wet, cool areas with a large amount of overcast (shady) weather, like the U.S. states of Oregon or Washington.
The main components of a habitat are shelter, water, food, and space. A habitat is said to have a suitable arrangement when it has the correct amount of all of these. Sometimes, a habitat can meet some components of a suitable arrangement, but not all.
For example, a habitat for a puma could have the right amount of food (deer, porcupine, rabbits, and rodents), water (a lake, river, or spring), and shelter (trees or dens on the forest floor). The puma habitat would not have a suitable arrangement, however, if it lacks enough space for this large predator to establish its own territory. An animal might lose this component of habitat—space—when humans start building homes and businesses, pushing an animal into an area too small for it to survive.
Space
The amount of space an organism needs to thrive varies widely from species to species. For example, the common carpenter ant needs only a few square inches for an entire colony to develop tunnels, find food, and complete all the activities it needs to survive. In contrast, cougars are very solitary, territorial animals that need a large amount of space. Cougars can cover 455 square kilometers (175 square miles) of land to hunt and find a mate. A cougar could not survive in the same amount of space that a carpenter ant needs.
Plants need space, too. Coast redwood trees, like the ones in Redwood National Park in the U.S. state of California, can reach more than 4.5 meters (15 feet) in diameter and 106 meters (350 feet) in height. A tree that massive would not have enough space to grow and thrive in a typical community park or yard.
Space is not the same as range; the range of an animal is the part of the world it inhabits. Grassland, for example, is the habitat of the giraffe, but the animal’s range is central, eastern, and southern Africa.
Food
The availability of food is a crucial part of a habitat’s suitable arrangement. For example, in the northern part of the U.S. state of Minnesota, black bears eat mostly plants, like clover, dandelions, and blueberries. If there were a drought, plants would become scarce. Even though the habitat would still have space (large forest), shelter (caves, forest floor), water (streams and lakes), and some food, it wouldn’t have enough to eat. It would no longer be a suitable arrangement.
Too much food can also disrupt a habitat. Algae is a microscopic aquatic organism that makes its own food through the process of photosynthesis. Nutrients like phosphorous contribute to the spread of algae. When a freshwater habitat has a sharp increase in phosphorous, algae “blooms,” or reproduces quickly. Algae also dies very quickly, and the decaying algae produces an algal bloom. The algal bloom can discolor the water, turning it green, red, or brown. Algal blooms can also absorb oxygen from the water, destroying the habitat of organisms like fish and plants. Excess nutrients for algae can destroy the habitat’s food chain.