 Producers, we call them auto-trophs, auto-trophs, self-feeding, these are the organisms which makes their own food by using sunlight as the energy source. They convert carbon dioxide and water into carbohydrates. Carbon dioxide, the inorganic form of carbon, the producers are the only source of all organic food present on the planet Earth. We also call them the entry point of energy in an ecosystem. They provide food to all other organisms, to all life forms. Examples of the auto-trophs, the producers includes the plants, algae, photosynthetic protista, photosynthetic bacteria. Next level is the heterotrophs, heterotrophs. Heterotrophs are the organisms which are also called the consumers. Heterotrophs mean that they are not able to make their own food and they have to acquire food from the environment. Usually through the auto-trophs, heterotrophs, the animals particularly, these are the organisms that do not make their food. They get their food from other organisms. They can get their food from other autotrophs, that is other organisms which are autotrophs, the producers, the herbivores, which have to eat upon other types of plants, different types of plants, maybe leaves of a tree, maybe grasses directly, maybe different parts of the plant, maybe fruits, maybe nuts, beans, or legumes. Anything else from plant, that is anything which is of plant origin, they may get their food energy by eating other animals. Now other animals may be the herbivores, that is plant-eaters. Those animals may be carnivores, themselves flesh-eaters, for example, the lions, the leopards, cats, they are all carnivores and they are also heterotrophs. That is another category of organisms which are called the chemotrophs, chemotrophs which make their food from chemicals. These are very specific life forms. These organisms use inorganic chemicals as their energy source and make carbohydrates. These are usually present in those areas of the ecosystem where light, the sunlight do not penetrate. For example, very deep zone of a lake, deeper zone of the ocean, where light do not penetrate, light cannot penetrate inside and photosynthesis is not possible. These organisms stays there, they have some specific metabolic pathways and enzymes, with the help of these enzymes and the metabolic pathways, they utilizes the energy present inorganic chemicals and convert it into ATP, the chemical form of energy and also makes organic molecules the carbohydrates. We call them chemotrophs, examples are some chemotrophic bacteria, there are different types of bacteria that live their life like this and there are some deep sea forms which are also chemotrophs and they produce their food through inorganic chemicals. Then there are types of consumers. Consumers are herbivores, if they are plant eaters, for example, the goats, the sheeps, the giraffes, very, very large-use animals, we see giraffes actually eats up the plants of, the leaves of very tall plants because they are too high, the elephants, some ancient dinosaurs were also herbivore. Then comes the carnivores, the secondary consumers which are, we also call them primary carnivores because they eat upon the herbivores, the frogs and snakes are very common examples. We know that the insects, many of the insects and the dragonflies, for example, they eat upon the grasses or they eat upon different plant parts and the frogs, they are insect eaters, they eat upon those insects. So frogs are very common secondary consumers or primary carnivores, snakes are another example of primary carnivores, usually the different types of rodents, the mice, the rats, they eat upon grains and they eat upon grasses, they eat upon different types of plant materials and the snakes consume those rodents. So snakes are acting as the primary carnivores or the secondary consumers. Then the tertiary consumers are the secondary carnivores, these are the organisms which eat upon the secondary consumers or the primary carnivores, for example, the hawks and the eagles, hawks usually eat upon the frogs and we know that frogs eat upon the insect and insects eat upon the grass. So the secondary carnivores or the tertiary carnivores, they actually eat upon another type of carnivore, eagle is another example, eagles, snakes eat upon the rats and mice and the rats and mice eat upon the grasses or the plant parts. So eagles are another example of the secondary carnivores, a goat in a picture you can see a goat eating upon grass, goat is a herbivore because it eats grass, grass is a plant producer, you can see a cat, cat is a carnivore, it usually eats upon meat, it is a meat eater but we know that nowadays cats became sort of omnivore because people give them food and they take that food in different forms like even sometimes cats, they eat the rice which is a plant material. You can see a squirrel which is eating upon nuts, parts of the plant again, so it is a herbivore. Then the decomposers, decomposers eat dead organic matter, animals and plants, their fallen plants, the dead organisms, we know that various plants shed their leaves and their branches in the fall. These leaves and branches go towards the soil and then they are merged into the soil. The decomposers bacteria or fungi present in that soil eat upon those dead organic matters and help the environment in a way that they convert those larger parts which are actually present in the soil, present on the soil or in the soil but are not available for acquiring any types of nutrients by plants or animals. The decomposers eat them and break them down into smaller parts, into smaller compounds and these compounds are then taken up by the roots of the plants and they become part of the plant and when animals eat plant they go back to the animal. So in this way the decomposers let the energy present in the ecosystem flow from soil towards the plants. For example we know that some plants have nodules like legumes. These plants have nodules around in their roots and there are bacteria which are associated with those nodules. These bacteria can fix nitrogen in the surrounding soil for these plants. There are different types of fungi which are present on the soil or there are different types of other bacteria present in the soil which can convert the dead bodies of the organisms or the fallen parts of plant into smaller compounds, compounds of nitrogen like ammonia, nitrates and nitrites which are later on taken up by the roots of the plants and plants use them for making their structures. When these structures are eaten by the animals like leaves, stem or some other part, fruit then these compounds go to the animals and they also use them for their life processes.