Food Chain
The food chain shown above depicts the relationship between predators (animals who naturally prey on other species) and their prey, such as herbivores (plant-eating organisms) in the desert. This chain shows a jackrabbit, an herbivore, eating the leaves of a bush. The energy the rabbit received from the bush is then transferred to the fox when the jackrabbit is eaten by it. The coyote hunts down the fox, showing energy transfer from the bush, jackrabbit , and fox to the coyote. Coyotes have few predators (animals higher on the food chain looking to eat them), but when they die, vultures will devour them.
Food Web
Shown above is a sample food web for the desert biome. The arrows from organism to organism represent the transfer of energy happening when one consumes the other. For instance, when a mule deer feeds on a patch of desert grass, the plant's energy is then transferred to the mule, and then to the mountain lion upon the consumption of the deer. Also displayed are the relationships between organisms. Plants are the producers (organisms that make their own food; autotrophs) and the source of energy in the desert biome. Animals that eat the plants are called primary consumers, and they serve as both predators (to plants) and prey (potential meals for animals higher on the food chain). In the same example, the mule deer is prey for the mountain lion, a natural predator, but also serves as a predator to the plants.
The food web also shows how all organisms are connected. An absence of one plant or animal might cause a whole species to die off. Say the ground squirrel's main food source goes missing. The population of ground squirrels would decrease, as well as the population of organism that primarily consumes them. The same affect might occur when a foreign species finds its way into the desert habitat. The new organism would eat another animal's source of food, causing competition (when two organisms or species must compete for food, shelter, mates, etc.) The new organism would throw off the food chain, having great effect on the habitat and its inhabitants. Populations can also be affected by density-dependent factors (factors whose effect varies depending on the density of the population) such as predation, migration, and food supply. Density independent factors (factors that change a population's size independent of its density.) including the weather and pollution play just as big of a role.
The food web also shows how all organisms are connected. An absence of one plant or animal might cause a whole species to die off. Say the ground squirrel's main food source goes missing. The population of ground squirrels would decrease, as well as the population of organism that primarily consumes them. The same affect might occur when a foreign species finds its way into the desert habitat. The new organism would eat another animal's source of food, causing competition (when two organisms or species must compete for food, shelter, mates, etc.) The new organism would throw off the food chain, having great effect on the habitat and its inhabitants. Populations can also be affected by density-dependent factors (factors whose effect varies depending on the density of the population) such as predation, migration, and food supply. Density independent factors (factors that change a population's size independent of its density.) including the weather and pollution play just as big of a role.
Energy Pyramid
The only organisms who who have 100% energy available are the plants, who produce their own food. When the plants are eaten by the insects, the energy level decreases by about 90%. This happens when the dove eats the insects, and when the hawk eats the dove. Energy is lost because plants receive their energy from the sun. The other animals cannot do that, so they have to get their energy from the plants. Because they can't go directly to the sun as a food source, energy is lost, and by the top of this pyramid, the hawk consumes only 1% of the available energy. The hawk must also eat more food to gain more energy since it does not eat plants or take in sunlight.