Heterotrophs in Ecology examples, types, and meaning

In heterotrophs, energy for life processes is obtained through the consumption of autotrophs. Some heterotrophs examples include members of the second and third trophic levels in an ecosystem. This article will discuss the types of heterotrophs, their meaning, and their role in ecology.

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Heterotrophs meaning

Heterotrophs are living things that cannot produce their own food through carbon fixation and must therefore obtain nutrition from other sources of organic carbon, primarily plant or animal matter.

What are heterotrophs?

Heterotrophs are organisms that obtain energy and nutrients from the consumption of other plants or animals. The term is derived from the Greek words hetero, which means “other,” and trophe, which means “nourishment.”

Heterotrophs live on the second and third levels of a food chain (which is a series of organisms that provide energy and nutrients to other organisms). Hence, heterotrophs are also called secondary and tertiary consumers. All animals and fungi, as well as some bacteria and protists and many parasitic plants, are examples of heterotrophic living organisms.

In microbiology, the term heterotroph arose in 1946 as part of a classification of microorganisms based on their type of nutrition. The term is now used in a variety of fields, including ecology to describe the food chain.

Heterotrophs examples

  1. Herbivores
  2. Carnivores
  3. Fungi
  4. Protists
  5. Photoheterotrophic cyanobacteria
  6. Iron-reducing bacteria

The above listed are some examples of heterotrophs and they will be discussed below.

This is African elephant is part of some heterotrophs examples.
This African elephant is an example of a heterotroph.

Herbivores

Herbivores are examples of heterotrophs because they eat plants (autotrophs) for their nutritional requirements. Thus, on the food web, they are known as primary consumers.

Herbivores include cows, sheep, deer, and other ruminant animals that ferment plant material in special chambers within their stomachs which contain symbiotic organisms. There are also, fruit-eating animals referred to as frugivores, such as birds, bats, and monkeys. These animals are also part of the heterotrophic herbivores.

In addition, there are also heterotrophic herbivores known as nectarivores that consume plant nectar such as hummingbirds, bees, butterflies, and moths.

Carnivores

Carnivores are usually predators that eat herbivores. Examples of heterotrophs that are carnivorous include snakes, birds, frogs (often insectivores), and marine organisms which consume zooplankton such as small fish, crabs, and jellyfish.

They may also be tertiary consumers or predators that prey on other carnivores and some examples of such includes lions, hawks, sharks, and wolves. Carnivores can also be scavengers, which are animals like vultures or cockroaches that eat dead animals; often, this is the carrion (meat) of animals that have been leftover from a predator’s kill.

The energy that carnivores can use as fuel is primarily derived from lipids (fats) that herbivores have stored within their bodies. Small amounts of glycogen (a polysaccharide of glucose that serves as a form of long-term energy storage) are stored in the liver and muscles and can be used for energy intake by carnivores.

Fungi

Fungi are heterotrophic organisms that feed by absorption rather than ingesting their food like other animals. Fungi have root-like structures known as hyphae that grow and form a network through the substrate on which the fungi feed. These hyphae secrete digestive enzymes, which break down the substrate and allow nutrients to be digested.

Fungi as an example of heterotrophs feed on a variety of substrates, such as wood, cheese, or flesh, though most of them specialize in a narrow range of food sources. Some fungi are highly specialized, and can only obtain nutrition from a single species.

Many fungi are parasitic, meaning they feed on their hosts without killing them. However, most fungi are saprobic, which means they feed on dead or decaying material such as leaf litter, animal carcasses, and other debris.

Saprobic fungi recycle nutrients from dead or decaying matter, making them available as nutrients to animals that eat fungi.

The fungi’s role as decomposers and recyclers at all trophic levels of the nutrient cycle is critical within ecosystems, but they are also economically valuable to humans.

Many fungi, such as yeast (Saccharomyces cerevisiae), are responsible for the production of human food, such as bread, beer, and cheese, and fungi, such as penicillin, are also used in medicine.

Protists

Protozoans, nonphotosynthetic algae, water molds, amoeba, and slime molds are examples of heterotrophic protists.

Photoheterotrophic cyanobacteria

Photoheterotrophic cyanobacteria are microorganisms with high photosynthetic efficiency and low growth requirements. Although these bacteria cannot use carbon dioxide as a carbon source, they can use solar energy to transfer electrons in the electron transport chain.

These bacteria inhabit aquatic or damp environments and feed on the organic compounds produced by autotrophic aquatic organisms.

Iron-reducing bacteria

Iron-reducing bacteria are bacteria that use reduced iron to produce energy by converting it to oxidized iron compounds. The energy produced by the process is then used for carbon source absorption and metabolism.

It has been proposed that these bacteria be used to decontaminate metal or metalloid polluted environments. Although iron-reducing organisms are commonly associated with extreme environments, they can also be found in less extreme environments. The presence of these bacteria in extreme environments can be attributed to the presence of inorganic compounds in such environments.

Are humans heterotrophs?

Humans are heterotrophs, with many of us also being omnivores and can eat a wide range of plants and animals.

By eating other organisms in the food chain, humans recycle nutrients and organic chemicals and use them in their bodies or defecate, assisting seeds of a variety of plants to germinate and spread to other areas of an ecosystem thus, increasing biodiversity.

In order to germinate, some plant seeds must pass through the digestive system of a heterotroph, or consumer (this process is called scarification, and it is the process that weakens the coat of seed so that the embryo of the plant can emerge).

Are bacteria heterotrophs?

Some bacteria are heterotrophs and are referred to as heterotrophic bacteria.

These bacteria derive their energy from organic compounds and are the most common and widely distributed forms. They can be aerobic or anaerobic, and they are everywhere, including food, soil, and water.

Because they are primarily responsible for the decomposition of organic matter, they aid in the recycling of natural substances. They also exist as parasites and cause a variety of diseases in plants, animals, and humans, and they are also found as symbionts in organisms, such as Rhizobium in legume root nodules.

Types of heterotrophs

  1. Organotrophs
  2. Lithotrophs
  3. Chemotrophs
  4. Phototrophs
  5. Photoorganoheterotrophs
  6. Chemolithoheterotrophs
  7. Mixotroph

Organotrophs

These heterotrophs use carbon compounds as electron sources, such as fats, proteins, and carbohydrates from animals and plants.

Lithotrophs

These heterotrophic organisms make use of inorganic compounds like ammonium, sulfur, and nitrite in order to obtain electron sources.

Chemotrophs

These organisms make use of the energy produced by the chemical oxidation process.

Phototrophs

This term refers to heterotrophic biological entities that use light to obtain energy and carry out metabolic processes.

Photoorganoheterotrophs

These organisms synthesize organic compounds by utilizing sunlight as well as the oxidation of organic substances such as elemental sulfur, thiosulfate, hydrogen sulfide, and molecular hydrogen.

Chemolithoheterotrophs

These heterotrophic organisms obtain their energy from the oxidation of inorganic compounds, for instance, the Oceanithermus profundus is a well-known example of a Chemolithoheterotroph.

Mixotroph

This is an organism that produces carbon dioxide from either organic carbon or carbon dioxide. Also, mixotrophs have the ability to use the methods of both autotrophs and heterotrophs. As a result, they can grow in both heterotrophic and autotrophic environments.

Autotrophs vs heterotrophs

The differences between heterotrophs and autotrophs can be viewed using several criteria like their definition, source of energy, types, position in the ecological pyramid, and examples.

What is the difference between autotrophs and heterotrophs?

Autotrophs differ from heterotrophs in that only autotrophs can produce their own food and do not require the consumption of other organisms for survival.

There is a huge difference between heterotrophs vs autotrophs in the ecosystem. To compare heterotrophs with autotrophs, it is seen that autotrophs can generate complex organic compounds from inorganic substances in one of two ways namely, photosynthesis or chemosynthesis.

While heterotrophs lack this ability and must rely on other organisms to survive. Therefore, the difference between autotrophs and heterotrophs is that the former mode of nutrition is via photosynthesis or chemosynthesis while the latter mode of nutrition is dependent on other organisms.

The table below compares the differences between autotrophs and heterotrophs.

Criteria for comparison
Heterotrophs
Autotrophs
Definition
These are organisms that are unable to synthesize their own organic carbon-based compounds from inorganic sources and must therefore rely on organic matter produced by or available in other organisms.
These are organisms capable of converting inorganic materials into nutritive organic molecules.
Position in the ecological pyramid
They occupy the second and third levels of the pyramid, hence they are known as consumers.
They occupy the first level of the ecological pyramid, thus they are called producers.
Types
Organotrophs, lithotrophs, chemotrophs, phototrophs, photoorganoheterotrophs, chemolithoheterotrophs, mixotroph
Photoautotrophs and Chemoautotrophs
Examples
Humans, animals, fungi, various protists, and some bacteria are all examples of heterotrophs.
Plants, photosynthetic algae, photosynthetic bacteria, methanogens, halophiles, nitrifiers, thermoacidophiles, and sulfur oxidizers are all examples of autotrophs.
The table shows the difference between autotrophs and heterotrophs.

Role of heterotrophs in the ecosystem

Heterotrophs are the consumers in the food chain or food web, which means they eat other forms of life because, unlike the producers, heterotrophs are unable to produce their own food. They can be found at all second and third levels of the food chain in a given environment, and each level is important to the ecology of that environment.

We start by classifying some heterotrophs as herbivores because they are primary consumers and they feed on autotrophic plants and/or other organisms that can produce their own food, such as phytoplankton and photosynthetic bacteria.

For instance, an antelope in a forest, an elephant in an African savannah, a manatee on a seagrass bed in Florida, a snail in a tropical forest, or a sea snail on a coral reef are all examples of herbivores or primary consumers.

These herbivores play a key role in maintaining the population of autotrophs in the ecosystem. They also help in seed dispersal and in the addition of inorganic nutrients through their waste and corpse.

There are some heterotrophic animals that are called carnivores because they eat other heterotrophs. Some examples of these heterotrophic organisms are a wolf in the forest eating a deer, a pride of lions in an African savannah eating an elephant, a shark in the Florida Keys eating a manatee, a salamander, and a toad both eating snails in the rainforest or a Giant Triton (a giant marine snail) eating other sea snails on a coral reef.

When they eat primary consumers, they are classified as secondary consumers.

The carnivores or secondary consumers play their part in the ecosystem by creating and maintaining a balance in the energy pyramid. As they consume or feed on the herbivores, they are indirectly reducing the carrying capacity of the ecosystem in terms of autotrophs available to feed herbivores.

Furthermore, some secondary consumers can also be tertiary consumers or top predators, which means they can eat both primary and secondary consumers, including themselves. Wolves, for example, are top predators because they can not only eat deer but also a fox (which is a carnivore) and in the African savannah, lions, and leopards can eat crocodiles, lizards, which are other carnivores.

In the marine world, orcas are the top predators in the ocean, because they can eat both sharks and carnivorous fish. Also, top predators in the bird world include eagles and hawks and in a coral reef, a Crown-of-Thorn sea star is a top predator.

These top predators help to checkmate the population of carnivores in the ecosystem. This is done in other to avoid overfeeding on the herbivores that will lead to the overpopulation of autotrophs and a subsequent decline in biodiversity.

Another important group of organisms found at higher trophic levels in the ecosystem is decomposers. This is an important group of heterotrophs that feed on dead and decaying materials in order to release inorganic compounds into the ecosystem. They are the ecosystem recyclers and are key in the biogeochemical cycle.

Functions of heterotrophs

  • They use organic carbon as a carbon source and organic chemicals as an energy and electron source.
  • Heterotrophs are consumers in the food chain.
  • They participate in the breakdown of complex organic compounds such as carbohydrates, lipids, and proteins.
  • Organic compounds are catabolized by heterotrophs through respiration, fermentation, or both.
  • They allow for dephosphorylation as part of the decomposition process.

FAQs

Are fungi heterotrophs?

All fungi are heterotrophic, which means they obtain their energy from other organisms. Fungi, like animals, extract energy from living or dead organisms via the bonds of organic compounds such as sugar and protein. Many of these chemicals can also be recycled and reused.

Are plants heterotrophs or autotrophs?

The majority of plants are autotrophs. However, some plants, known as heterotrophic plants, cannot produce their own food and must obtain nutrition from outside sources. This type of feeding can occur with parasitic or saprophytic plants, as well as plants that are mutualistic symbionts, epiphytes, or insectivorous.

Are all animals heterotrophs?

All animals are heterotrophs, but the type varies depending on what they prefer to eat. The majority of herbivores eat only plants and other photosynthetic autotrophs and never other animals. Some heterotrophs can be both primary and secondary consumers, especially when you take a look at a bear as an example. Bears can consume fruits and vegetables, but they can also consume other animals.

How do heterotrophs obtain energy?

Heterotrophs obtain energy as they feed on the complex organic molecules prepared by autotrophs, generate energy through respiration, and emit carbon dioxide.

What are autotrophs and heterotrophs?

Autotrophs are referred to as producers because they can produce their own food from raw materials and energy and plants, algae, and certain bacteria are examples of autotrophs. While heterotrophs are known as consumers because they consume other consumers or producers. Some examples of heterotrophs include dogs, birds, fish, and humans.

What is the heterotrophs definition?

A heterotroph is defined as an organism that cannot produce its own food and must rely on other sources of organic carbon, primarily plant or animal matter, for nutrition. Heterotrophs are primary, secondary, and tertiary consumers, but not producers, in the food chain. Therefore, they occupy the second and third trophic levels in the energy pyramid of an ecosystem.

Are protists heterotrophs?

Protists acquire nutrition in a variety of ways. Some are photosynthetic autotrophs, which means they feed themselves and can use sunlight to generate carbohydrates. Other protists are heterotrophs, meaning they get their food from other organisms.

What are some examples of autotrophs and heterotrophs?

Some examples of autotrophs are algae, cyanobacteria, maize plants, grass, wheat, seaweed, and phytoplankton.

While some heterotrophs examples include carnivores that consume the flesh of other animals, herbivores that consume plants, and omnivores consume both meat and plants. There are also scavengers who eat the remains of carnivores and herbivores and decomposers that decompose dead plant or animal matter into the soil, while detritivores consume soil and other very small bits of organic matter.

What is the difference between heterotrophs and autotrophs?

Autotrophs differ from heterotrophs because they are organisms that prepare their own food through photosynthesis, whereas heterotrophs cannot prepare their own food and must rely on autotrophs for nutrition.

Why are humans called heterotrophs?

Humans lack the physiological mechanism to produce their own food from raw materials found in their surroundings as plants. As a result, humans consume plants and other animals to meet their energy requirements. Hence, humans are classified as heterotrophs because they are organisms that obtain food or energy from sources other than their own.

Can heterotrophs do photosynthesis?

Heterotrophs do not perform photosynthesis and it is another significant distinction between autotrophs and heterotrophs is that autotrophs have a pigment called chlorophyll that allows them to capture the energy of sunlight during photosynthesis, whereas heterotrophs do not because photosynthesis would be impossible without this pigment.

What does the amount of food available for heterotrophs depend on?

The amount of food available depends on an organic carbon source that began as part of another living organism. Heterotrophs rely on autotrophs for nutrients and food energy, either directly or indirectly.

Are archaea autotrophs or heterotrophs?

No, because archaea are single-celled organisms that can occasionally be found in colonies. Archaea are autotrophic (they produce their own food) and use chemical synthesis to do so.

What are some multicellular heterotrophs?

Animalia is a kingdom of multicellular, heterotrophic organisms, and humans, other primates, insects, fish, reptiles, and a variety of other animals are all members of this kingdom.

Can heterotrophs make their own food?

No, because heterotrophs must obtain organic molecules that have been synthesized by autotrophs.

Are algae autotrophs or heterotrophs?

Algae are autotrophs and not heterotrophs because they can produce their own food through photosynthesis.

Are decomposers heterotrophs or autotrophs?

Decomposers are heterotrophic organisms that decompose and feed on the remains of dead organisms as well as other organic wastes such as feces. Nevertheless, there are other examples of heterotrophs that are not decomposers such as herbivorous and carnivorous organisms.

How do heterotrophs obtain fixed carbon?

Heterotrophs obtain high-energy carbon compounds from autotrophs by consuming them and breaking them down through respiration.

How does photosynthesis benefit heterotrophs?

First, photosynthesis converts carbon dioxide (a byproduct of respiration) into oxygen (necessary for respiration). As a result, heterotrophs rely on photosynthesis for oxygen, and furthermore, photosynthesis feeds the organisms that heterotrophs consume in order to survive.

Are trees autotrophs or heterotrophs?

Trees, like all other plants, are autotrophic and not heterotrophic organisms, which means they can produce food through photosynthesis.

Are all invertebrates heterotrophs?

Invertebrates cannot produce their own food, so their diet is heterotrophic. In order words, they are heterotrophs.

Why are heterotrophs called consumers?

Heterotrophs are known as consumers because they consume producers or other consumers and they occupy the second and third levels of a food chain, which is a series of organisms that provide energy and nutrients to other organisms.

What is the relationship between autotrophs and heterotrophs?

The relationship between autotrophs and heterotrophs starts with autotrophs as they are in the first trophic level because they do not consume other organisms. They are closely followed by herbivores, or organisms that eat plants, consume autotrophs, and occupy the second trophic level as heterotrophs. The third trophic level includes heterotrophs that are carnivores (animals that eat meat) and omnivores (animals that eat all types of organisms).

Are carnivores autotrophs or heterotrophs?

Secondary consumers (carnivores) are heterotrophs.

Are amoebas autotrophs or heterotrophs?

Amoebas are not autotrophs; rather, they are heterotrophs. Amoebas, as heterotrophs, consume other organisms or organic material to fuel their growth.

Do heterotrophs produce their own food?

Heterotrophs are organisms that are unable to produce their own food from light or inorganic compounds; instead, they feed on other organisms or their remains.

Which kingdom contains heterotrophs with cell walls of chitin?

The Fungi kingdom is the kingdom that contains heterotrophs with cell walls of chitin.

Are animals heterotrophs or autotrophs?

Animals are heterotrophs and not autotrophs because they can’t manufacture their own food. Hence, they feed on other organisms.

Which organisms are heterotrophs?

Herbivores, carnivores, fungi, protists, photoheterotrophic cyanobacteria, iron-reducing bacteria, etc

Heterotrophs rely on autotrophs to do what?

In heterotrophs, energy for the life process is dependent on other organisms. Hence, heterotrophs rely on autotrophs and other heterotrophs for their source of energy.

A video briefly pointing out some heterotrophs examples.

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