Every living organism in the world needs energy to survive. Some organisms can make their own food which provides them the energy needed, such as plants and algae. Most organisms cannot make their own food, such as humans. The two types of organisms are classified accordingly, known as autotroph and heterotroph.
Plants and algae use the sunlight, chlorophyll and water to make their own food. The food is simple glucose and they also produce oxygen in the process. Without sunlight or chlorophyll and without water, the plants would not be able to produce their own food. These plants and animals are autotrophs. All other organisms rely on these plants and algae to get the energy they need. Such organisms are called heterotrophs. Hence, human beings, reptiles, birds and all members of the animal kingdom as well as microorganisms such as parasites are heterotrophs.
Types of Heterotrophs
Autotrophs are of two types. One type relies on photochemical reactions, which means the plants need light to synthesize their own food. The other type relies on chemical reactions. The two are respectively called photoautotroph and chemoautotroph. Likewise, heterotrophs are chemoheterotroph and photoheterotroph depending on the way they consume the food and obtain the energy.
Heterotrophs can be further classified into two types based on how they consume the food. Some heterotrophs consume the food through ingestion, like humans, tigers, monkeys, birds and most animals that you see around you. Most of the wildlife would ingest plants, other animals and different kinds of agricultural produce including fruits. These animals would then digest the food and produce energy. The food would provide the necessary nutrients.
The other type of heterotrophs would consume food by absorption. They don’t ingest their foods but absorb the food through their bodies. An example is fungus. Fungus doesn’t have the ability to consume food as humans ingest and they don’t have a so called digestive system either. They absorb the food through the surface and use the energy to survive.
Heterotrophs may feed on autotrophs or other heterotrophs. Also, some heterotrophs can synthesize some nutrients on their own. For instance, although humans cannot make their own food, they can produce their own vitamin D and numerous enzymes that help in the breaking down of food leading to absorption of the nutrients.
Autotrophs are considered the provider because they produce food and heterotrophs are referred to as the consumer. That also defines the food chain.