Differences between Autotroph and Heterotroph - Autotroph vs Heterotroph

What is Autotroph?

An autotroph is one of the groups of organisms that can produce their own food using diverse substances like sunlight, water and various other chemical compounds.
The word autotroph is composed of two words, ‘auto’ meaning self and” meaning self, and ‘troph’ which means food.

Autotrophs are therefore capable of creating their own food, without assistance from other animals.
Autotrophs are also known as ‘producers since they are the foundation of eco-friendly food chain and are the primary source of every other food source for other living organisms.
They are vital because all life forms depend directly , or indirectly on them to provide energy and food.

The most widely known autotrophs are the plants. However numerous other types of autotrophs can be seen in nature, such as phytoplankton to algae and even some bacteria.
Photosynthesis is the most common method used by autotrophs to convert solar energy into chemical energy. However, some autotrophs also use other methods such as chemotrophy and phototrophy.
All green plants have chlorophyll as the pigment that is used that is responsible for photosynthesis. Other pigments such as bacterial rhodopsin and carotenoids are also present in algae, bacteria and phytoplankton that are used for photosynthesis.

A few rare autotrophs create food through the process of chemical synthesis that derives power from chemical reaction instead of sunlight.
Organisms that perform chemosynthesis reside in extreme environments, where harmful chemicals needed to perform the reaction are present. In volcanoes, bacteria use sulfur for their food production.
Autotrophs are the first trophic level within the food chain. The organisms then get consumed by herbivores, which create the second trophic layer and the cycle continues.

A rise in the number of autotrophs ultimately increases the amount of people who consume. A decrease in the amount of autotrophs results in starvation to all other levels of trophic trophics.

Classification of Autotrophs

Autotrophs are phototrophs, or Chemotrophs. Photosynthesis is a method that makes use of water and carbon dioxide to make sugars using sunlight. Phototrophs convert light energy into chemical energy through the reduction of carbon. Autotrophs during photosynthesis reduce carbon dioxide in the atmosphere and produce organic substances in the form of simple sugars that store the energy from the sun. Photosynthesis converts water into oxygen and releases it to the air. The sugar glucose can be polymerized to create storage sugars such as starch and cellulose, which contain long-chain carbohydrate. Fats and proteins are also produced through the polymerization process of glucose too. Examples of phototrophs are algae such as Kelp, protists, euglena phytoplankton, and bacteria such as cyanobacteria.

Chemotrophs, in contrast make use of electron donors that come from organic or non-organic resources for an energy source. Lithotrophs utilize electrons from inorganic chemical sources such as ammonium ions, hydrogen sulfur ferrous ions, as well as elemental sulfur. Both lithotrophs and phototrophs make use of ATP produced by photosynthesis or the oxidation of inorganic compounds to generate NADPH through the reduction of NADP+ and forming organic compounds. Most bacteria like Acidithiobacillusferrooxidans, which are an iron bacteria, Nitrosomonas, which are nitrosifying bacteria, Nitrobactor which is a nitrifying bacteria, and Algae are examples for chemolithotrophs.

Chemotrophs typically occur on the ocean floor where sunlight cannot reach. A black smoker that is a hydrothermal vent located on the seabedand that has more sulfur is a fantastic source of sulfur bacteria.

Examples of Autotrophs

Green Plants

Green plants comprise the largest autotrophs group that makes use of sunlight to facilitate the assimilation of inorganic compounds into organic compounds. Plants have chlorophyll as a pigment for photosynthetic use which is capable of capturing sunlight, which can be transformed into chemical energy through different metabolic pathways.

Primarily, herbivores depend upon plants as food and energy and secondary consumers like carnivores depend indirectly on plants. Green plants are the first trophic stage of the food chain, and provide the energy needed to be spread throughout the chain. Plants use sunlight and carbon dioxide to make carbohydrate (glucose) as well as oxygen.

Green algae

Green algae belong to a different kind of organism that is able to produce food themselves through photosynthesis. These are photoautotrophs . They can be found mostly in wetlands and ponds.

They, too, like plants have chlorophyll as their photosynthetic pigment that captures the sun’s energy needed to power the process. Green algae form green mats that are found on the ground, which aids in bringing oxygen to the air.

Nitrosomonas

Nitrosomonas is a type of nitrogen fixing bacteria that transform the molecular form of nitrogen to an organic substance that is consumed by plants that are found in soil. They are chemoautotrophs which utilize the energy created by the chemical reaction to provide a method to prepare food. They absorb nitrogen, and then reduce it to an nitrate-like form which can be integrated into plants in the form amino acids. This is because of the reaction that is involved in nitrogen fixation they gain the energy required for the preparation of amino acids.

What is Heterotroph?

A heterotroph is a class of organisms who get their nutrition from other organisms and aren’t able to produce their own food.
The word heterotroph is comprised of two words: ‘hetero’ meaning others and” meaning other people and “troph” which means food.
Heterotrophs are also referred to as consumers since they consume food cooked by autotrophs. These organisms are able to form higher levels of trophic level in the food chain.

Heterotrophs are further classified into two categories according to the energy source they draw from. Photoheterotrophs draw its energy through light, but depend on the producers to provide their carbon sources.
Chemoheterotrophs In turn, get both their carbon and energy through other sources.
Certain heterotrophs directly depend on autotrophs to feed such as herbivores that feed on plants. Others heterotrophs indirectly depend on producers through feeding on the first form of heterotrophs.

Most heterotrophs rely on photosynthesis in a variety of different ways. Along with providing energy and nutrition as well, photosynthesis provides oxygen to heterotrophs.
The carbon compounds reduced by autotrophs then get converted by heterotrophs to create energy that is needed for their reproduction and growth.
Heterotrophic nutrition can further be divided into three categories: parasitic nutrition, saprotrophic nutrition and holozoic nutrition.

Saprotrophs are a type of heterotrophs that eat the decaying and dead organic matter to produce carbon, energy, and nutrients.
Holozoic organisms belong to a different category of heterotrophs which consume solid food items from other organisms. They break down their food to smaller pieces before being transported to various parts of the body.
Parasites are heterotrophs, which means they depend upon other species for all types of food. In this way parasites are benefited while the host does not.

Classification of Heterotrophs

Two kinds of heterotrophs can be distinguished based on their source of energy. Photoheterotrophs use sunlight to generate energy source, while chemoheterotrophs use chemical energy. Photoheterotrophs, like purple non-sulfur bacteria, green non-sulfur bacteria, and Rhodospirillaceae generate ATP from sunlight in two ways: bacteriochlorophyll-based reactions and chlorophyll-based reactions. Chemoheterotrophs can be either chemolithoheterotrophs, which use inorganic carbon as the energy source, or chemoorganoheterotrophs, which use organic carbon as the energy source. Example for chemolithoheterotrophs are bacteria like Oceanithermus profundus. Examples forchemoorganoheterotrophs are eukaryotes like animals, fungi and protists.

Examples of Heterotrophs

Animals

Animals constitute the bulk of the living organisms that are food chain. They are the consumers at trophic levels in the food chain. All animals are heterotrophs dependent in some way or another on plant and products for energy and food. Herbivores are the main consumers that directly eat plants and are the primary source of carbon. Carnivores are the second-tier consumers who consume herbivores as food sources. They get carbon in organic form and then break it into energy to fuel expansion and reproduce. Humans, being omnivores, are omnivores, and eat both animals and plants, and therefore are heterotrophs.

Fungi

The fungi are heterotrophs, which don’t consume autotrophs but instead take in their food. They are saprophytes that are able to feed on nutrients, not organic matter. Most saprophytic fungi reside in areas of decaying and dead matter because they provide simple sources of energy. They produce digestive enzymes that aid in breaking down food into smaller pieces before eating them. Certain fungi are parasites and feed on the host and with out harm to the host. Fungi are decomposers within the food chain and help recycle energy back into the atmosphere for autotrophs to take.