Organisms that independently synthesize useful substances that they need for life are called autotrophic. This type of nutrition is also called "autotrophic". For these living organisms, an environment with the presence of carbon dioxide, water, inorganic s alts and a certain source of energy is sufficient for existence. Purple bacteria and green plants feed on photosynthesis. Some bacteria have a type of nutrition in which they obtain useful compounds through the oxidation of various inorganic substances, such as hydrogen sulfide and ammonia. The source of energy is most often sunlight.
Creatures that use heterotrophic nutrition are unable to synthesize the substances they need on their own. They are forced to use ready-made connections. Therefore, the heterotrophic type of nutrition is carried out at the expense of autotrophs or the remains of other organisms. Thus the food chain is formed. Creatures that use this type of food include most bacteria, fungi and allanimals.
There are different types of heterotrophs. Some creatures can eat others or their individual parts, and then digest. This is a holozoic type of nutrition. Such creatures constantly hunt to feed themselves. Cats eat mice and birds, frogs eat mosquitoes and flies, owls eat rodents, and so on. Organisms that have this type of nutrition are endowed with certain sense organs, muscular and nervous instruments. This arsenal helps them find and catch prey. The transformation of food into molecular compounds that the body can absorb takes place in the digestive system.
Some plants (sundew, venus flytrap), in addition to photosynthesis, can still get food by hunting. They catch, lure and digest various insects, as well as some small animals. Such plants are called "insectivorous".
Herbivores feed on plant food and receive energetically valuable compounds from its cells, which are synthesized by green plants.
Another group of holozoan animals (carnivorous predators) use a type of diet in which they eat herbivores or other predators. Some of them are omnivorous and can eat both plant and animal food.
Initially, all heterotrophic creatures receive energetically valuable substances from autotrophs. Green plants synthesize these compounds through photosynthesis. Sunlight is the main source of energy. Without him there would be nolife on the planet, as it is the basis of all nutrients.
Most varieties of bacteria, yeasts and molds do not have the ability to swallow food whole. They feed through cell membranes. This type of heterotrophic nutrition is called saprophytic. These creatures can only live in places where there are decaying plant or animal organisms, or a significant amount of their waste products.