It consist of a sequence of organisms starting with a producer (i.e. plants), followed by a primary consumer, the secondary consumer and ending with the tertiary consumer.
A simple food chain could start with the grass (producer), which is consumed by rabbits (primary consumer), who get consumed by foxes (secondary consumer).
Grass -> Rabbit -> Foxes
Sometimes, you may find that a food chain can appear more complex than the one above.
Take a look at the below illustration.
GRASS -> Grasshopper -> Rat -> Snake -> Hawk -> Mushroom -nutrient-> GRASS
After the hawk dies, fungi (like mushrooms and other decomposers break down the carcass and turn the remains of the hawk into nutrients, which are released into the soil.
The nutrients (with other factors like sunshine and water) will cause the grass to grow.
FOOD CHAIN AND ENERGY
In a food chain, energy is passed from one link to the other. When a herbivore eats, only a fraction of the energy that it gets from its food becomes new body mass; the rest of the energy is lost as waste or used to carry out its life processes, such as movements, digestion and reproduction.
When a herbivore is eaten by a carnivore, it passes only a small amount of its total energy to the carnivore. Of the energy transferred from the herbivore to the carnivore, some energy will be "wasted" or "used up" by the carnivore. The carnivore then has to eat many other herbivores to get enough energy to grow.
Because of the large amount of energy that is lost in each link, the amount of energy that is transferred through the links get less.
The further along the food chain you go, the less food there is, and hence, less energy remains available. In other words, a large mass of living things at the base is required to support a smaller number of consumers at the top of the link. Hence, many herbivores are needed to support a few carnivore.
Will a change in the size of one population affect another population in the same food chain?
Yes, it will. This is because populations within a food chain are inter-independent upon one another.
For example, where there are too many giraffes, there will be insufficient trees and shrubs for all of the to eat.
Hence, more giraffes will tend to starve or die. On the other hand, where there are a fewer giraffes, it means trees and shrubs in the area have more opportunity to grow to maturity and to multiply.
Fewer giraffes also means less food is available for lions to feed on and more lions may starve to death.
Hence, where there are a fewer lions, the giraffe population may increase
Biodiversity is not only important to the environment, but also to the well-being of Man.
Importance of biodiversity to Man.
Many plants and animals provide various goods of products to humans, many of which play important roles in human economies.
Plant and animal diversity provides a variety of food for Man.
3.Medicines and herbs
Many plants are rich sources of traditional and modern medicines. These are used to treat and prevent diseases.
The wealth of gene pools increases diversity in future generations. Eg: for better crops.
All species are supported by the interactions among other species, each providing an ecological value to another such as pollination, nutrient cycling and also the regulation of the atmosphere and climate.
Plant and trees provide oxygen to the atmosphere; wetlands and forest provide clean water through filtration.
•A camel provide transportation, food and milk to Man. Their skin is also used to make clothing and tents for shelter against desert winds.
•Trees take in carbon dioxide from the atmosphere and release oxygen durin photosynthesis. They also prevent soil erosion and reduce the surrounding temperature on a hot day.
•Bees are important agents of pollination; hence, they contribute to the continuance of species. Bees also make honey, which is consumed by Man as food and medicines.
•The fish provides Man with food for survival. It is rich source of protein too.
•Mushrooms and fungi are a source of medicines, and they are also food for Man. Mushrooms are agents for the break down and decay of wood and leaves into humus and compost, which are vital for plant growth.
A food chain demonstrates the feeding relationship between living organisms in an ecosystem.