HETEROTROPHIC ORGANISMS: CHARACTERISTICS, TYPES, EXAMPLES - BIOLOGY - 2025

The heterotrophic organisms are living beings who do not possess the ability to produce their own food. Because of this, they use various sources of organic carbon to obtain the energy and nutrients they need. An example of a heterotrophic organism is a lion, since it needs an external source to feed itself. On the contrary, plants are autotrophic organisms that generate their own food.

Plants and animals are the main suppliers of energy substances and compounds required by heterotrophic organisms. These organic elements allow the carrying out of the various metabolic processes, essential for sustaining life.

Heterotrophic animal. Source: pixabay.com.

In the food chain, where there is a flow of nutrients through various food relationships, heterotrophic organisms play the role of first, second or third order consumers. In this sense, their diet is based on the consumption of organic matter, contrary to the producers who can synthesize it.

Some examples of heterotrophic beings are fungi, lion, rabbit, man, monkey, and eagle, among others.

Characteristics of heterotrophic organisms

- They feed on natural sources

Heterotrophs feed on organic carbon, mainly from other animals or plants. These natural sources include a wide range of elements.

Thus, some beings use fats, proteins or carbohydrates as electron suppliers, while others obtain them from inorganic compounds such as nitrite, ammonium or sulfur.

- They are consumers

In the food chain, heterotrophs function as consuming organisms. Thus, there are primary consumers, such as the rabbit, which feeds directly on the producing beings (plants).

The next trophic level is formed by secondary consumers, who hunt and consume other animals (primary consumers), from which they obtain their energy. As for tertiary or third-order consumers, they feed on second-order animals.

- Decomposers

Some heterotrophs are responsible for harnessing the energy and matter that exists in plant or animal remains and transform it into inorganic matter, which returns to nature. An example of this group are some bacteria and fungi.

- Release of energy

When autotrophic organisms eat food they have to metabolize it. In the processes of metabolization of food substances, the release of energy occurs. This occurs during the oxidation of hydrogen and carbon atoms, which are present in lipids, carbohydrates, and proteins.

- Fermentation and respiration

Heterotrophs have the ability to catabolize organic compounds through fermentation, respiration, or through both processes.

In this sense, fermentation and respiration carried out by heterotrophic microbes are responsible for a large part of the release of atmospheric CO2. This represents for autotrophic beings, such as plants, an important source of this element, which is essential for the performance of photosynthesis.

Types of heterotrophic organisms

- According to the energy source

Photoheterotrophs

Photoheterotrophs get their energy from sunlight. As for carbon, it comes from organic material and not from carbon dioxide, as occurs in autotrophs.

In this group of living beings, ATP production occurs through photophosphorylation, starting from organic compounds, which they obtain from the environment. Some of the representative bacteria are heliobacteria, green bacteria without sulfur, and purple bacteria without sulfur.

Chemoheterotrophs

Chemoheterotrophs lack the ability to synthesize the organic molecules that it requires to fulfill their vital functions. Because of this, these organisms must consume carbon molecules, such as lipids and carbohydrates, which are synthesized by other organisms.

However, energy and total carbon come from the same chemical compound, such as glucose. As for the source of energy in chemoheterotrophs, they are the electrons that make up the hydrogen atoms, contained in organic molecules.

- According to the type of nutrition

Saprophytes

Fungi, bacteria and mold

Saprophytes are heterotrophic organisms that obtain energy from dead organic material or debris that have been disposed of by other living things. Thus, they can extract compounds that they require as nutrients to carry out vital functions.

Parasites

In this type of heterotrophic nutrition, living beings inhabit the host's body and feed on it. As for the host, it does not get any benefit from the presence of the parasite, but it could be seriously harmed, which could even cause death.

Holozoic

In this, the animal ingests solid or liquid foods, which are subjected to various processes in the different organs that make up the digestive system. Thus, the organic matter consumed is degraded into smaller molecules, which are assimilated with tissues and cells of the body.

- According to the origin of the source

Herbivores

Herbivores are animals that base their diet on the consumption of plant species. In the food chain they constitute the group of primary consumers. Examples: rabbit, deer, llama, and hare.

Carnivores

To this group belong the heterotrophic animals that obtain nutrients and energies mainly through the consumption of meat, either by predation or by eating carrion. Examples: tiger, jaguar, hyena, and lion.

Omnivores

Omnivores are those animals whose diet is based on both plants and animals. Regarding their behavior, they are usually generalists and opportunists. Examples: the human being and the bear, with the exception of the panda and the polar bear.

Decomposers

These living things use enzymes, in conjunction with various chemical reactions, to break down dead organic matter. Bacteria are a clear example of this type of heterotrophic organism.

Examples of heterotrophic organisms

Tiger

The tiger is a predator that consumes meat as the main source of nutrients and energy. This carnivore has evolved large fangs which, together with strong jaw muscles, allow it to tear the skin of the animal it has hunted.

Heliobacteria

This photoheterotroph requires sources of organic carbon, coming from the soil, especially those that are saturated with water. Regarding their importance, heliobacteria are very useful organisms in the fertility of the land where there are rice crops.

Mushrooms

These multicellular organisms obtain their nutrients from organic matter, on which they act to break it down. This occurs because fungi produce exoenzymes that degrade food, to convert it into elements that can be absorbed.

The role in nature of disintegrating heterotrophs is crucial, since they return various substances assimilable by other living beings to the environment. This contributes to the flow of energy and nutrients through ecosystems.

Cow

This herbivorous animal bases its diet on the consumption of plant material, such as grasses and legumes. Thus, due to the high fiber content and the need to digest the cellulose molecules that make up the forage, the digestive system of this ruminant has several adaptations.

Among these is your stomach, which is divided into four cavities: the rumen, the reticulum, the omasum, and the abomasum.

Leeches

These parasitic organisms absorb blood from the host's body surface to feed themselves.

Termites

Termites rely on microbes in their gut or digestive tract to feed themselves. These microbes convert the complex sugars present in wood into simpler molecules.

Cockroaches

Like other scavengers, cockroaches feed on dead animals. However, they also eat plants, paper, and other materials.

Flies

Flies often feed on wounds in sheep, cattle, and other animals. In this way, they eat the dead meat around the wound, while the animal remains relatively healthy.

Sea turtles

Olive ridley turtle

Kemp's ridley and flat turtles are omnivorous; that is, they feed on animals and plants.

Green turtles are herbivorous as adults, but omnivorous at birth. Similarly, loggerhead turtles are carnivorous as adults but omnivorous as hatchlings.

References

1. Hussain Kanchwala (2019). What Are Heterotrophs ?. Recovered from scienceabc.com.
2. Microscopemaster (2019). Heterotrophs, Definition, Nutrition, vs Autotrophs. Recovered from microscopemaster.com.
3. Jarod Saucedo (2019). Ten Examples of Heterotrophs: Learn About Creatures that Eat Other Producers. Recovered from brighthubeducation.com
4. Wikipedia (2019). Heterotroph. Recovered from en.wikipedia.org.
5. James, Thomas. (2019).Types of Heterotrophic Bacteria. Sciencing. Recovered from sciencing.com.