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Heterotroph – Definition, Types, Importance, Examples

What is Heterotroph?

  • A heterotroph is a living thing that cannot make its own food. Instead, it gets its nutrition from other sources, like plants or animals. Heterotrophs are not the ones that make food; they eat food made by other living things. Animals, fungi, some bacteria, and certain tiny organisms are all examples of heterotrophs.
  • Imagine a food chain, where some organisms make food and others eat that food. Heterotrophs are the ones that eat the food. They can be like the first, second, or third group of eaters in this chain. But they are not the ones at the start that create food.
  • Heterotrophs can be split into different types depending on where they get their energy. Some use chemicals to get energy, like humans and mushrooms. Others use light, like certain bacteria.
  • When we look at how living things get their nutrition, there are two main ways. One way is autotrophs, which can make their food using things like sunlight or chemicals. Heterotrophs are the other way. They need to eat food that is already made by other living things to get their energy.
  • Heterotrophs eat food containing important stuff like sugars, fats, proteins, and more. These things help them stay alive and do everything they need to do. They use these things to grow, make babies, and do all the important tasks that keep them alive.
  • So, a heterotroph is an organism that can’t make its own food and needs to eat from other living things to survive and thrive.

Definition of Heterotrophs

Heterotrophs are organisms that rely on eating other living things for their nutrition and energy, as they cannot produce their own food.

Heterotroph Infographic
Heterotroph Infographic

Types of Heterotrophic Nutrition

In the natural world, living things use different ways to get their food when they can’t make it themselves. These are the main types:

  1. Holozoic Nutrition: Some organisms eat solid food, like when we eat our meals. They take in chunks of food and digest it inside their bodies to get energy. Animals, like us, use this type of nutrition.
  2. Saprophytic Nutrition: Others feed on stuff that’s already dead and rotting. It’s like eating leftovers! These organisms break down the dead things and take the nutrients they need. They help clean up the environment.
  3. Parasitic Nutrition: Some organisms live off other living things, but not in a good way. They attach to the host and take nutrients from them, often causing harm. It’s like a one-sided meal for them. This can be bad for the host, as they lose out on nutrients and might get sick.

So, these are the different ways that living things who can’t make their own food get what they need to survive. They either eat solid food, feed on dead things, or take from others – sometimes to the detriment of their hosts.

1. Holozoic Nutrition

Holozoic nutrition is when certain living things eat whole food by taking it into their bodies. The word “holozoic” comes from two Greek words: “holos” which means whole, and “zoic” which means animal. Let’s learn more about it:

Eating Process: In holozoic nutrition, the living thing takes in solid food. This food is then broken down further inside the body and moved into the cells for energy.

Examples of Holozoic Eaters:

  1. Human Beings: We eat a variety of foods to get our energy.
  2. Other Mammals: Animals like dogs, cats, and cows also use holozoic nutrition.
  3. Single-Celled Organisms like Amoeba: Even tiny creatures like amoeba use this way of eating.

Types of Holozoic Eaters:

  1. Herbivores: These animals only eat plants. Depending on the animal, they might eat leaves, fruits, or other parts of plants. For example, cows eat grass, while giraffes can eat leaves from thorny plants.
  2. Carnivores: Carnivores eat other animals. They only eat meat, and they are adapted to hunt and kill for their food.
  3. Omnivores: Omnivores eat both plants and animals. This includes humans, bears, raccoons, and more.

Holozoic eaters are important because they help to move energy through the food chain. Plants make food for themselves, and holozoic eaters like herbivores, carnivores, and omnivores eat those plants or other animals to get energy. This energy is then passed on to other creatures in the ecosystem.

2. Saprophytic Nutrition

Saprotrophic nutrition is when certain living things eat from decaying organic matter, like dead animals or plants. These living things are called saprotrophs or saprophytes. Let’s understand this more:

Saprotrophs: These are organisms that get their food from stuff that’s no longer alive and is breaking down. They do this by absorbing the nutrients from the decaying matter. Some of these are fungi, bacteria, and water molds.

How They Eat: Saprotrophs use special tools called enzymes to break down the decaying matter into simpler bits. Then they absorb these bits, which become their food. Even though some saprotrophs, like fungi, might look a bit like plants, they can’t make their own food. They have to get it from the decaying stuff.


  • Saprophytic Fungi (Mucor): Fungi like mucor spread tiny threads called hyphae through the dead stuff. These threads soak up the nutrients as they grow. Enzymes made by the fungi break down the dead stuff into simpler bits that the fungi can use.
  • Saprophytic Yeast: Yeast, another type of fungi, is made of single cells. They release enzymes into their surroundings to break down dead things. Then they absorb the nutrients from the broken-down stuff.

So, saprotrophic nutrition is like being a nature’s recycler. These special living things help break down dead things and take in the useful parts as their food.

Conditions required by saprophytes for nutrition

For saprophytes to get their food, they need certain conditions to be just right. These conditions are like their recipe for eating. Let’s see what they need:

  1. Water (or Moisture): Just like we need water to stay healthy, saprophytes need it too. It helps them absorb nutrients from the decaying stuff.
  2. Oxygen (some organisms like yeast do not need oxygen): Most saprophytes like to breathe in oxygen. It helps them do their work. But some, like yeast, can manage without it.
  3. Neutral or Mildly Acidic pH: pH is like a measure of how acidic or basic something is. Saprophytes prefer things to be neither too sour nor too basic. They like it just right.
  4. Warm Temperature Range: Saprophytes are like Goldilocks – they want the temperature to be not too hot and not too cold, but just right. A warm range is their favorite.

So, for saprophytes to munch on decayed stuff, they need water, oxygen (sometimes), a not-too-strong pH, and a cozy warm temperature. They’re like little chefs making their meal just perfect!

Importance of saprophytic fungi

Saprophytic fungi are like nature’s cleaners, and they do a lot of important jobs:

  1. Decomposers: These fungi break down things that are no longer alive and turn them into simpler bits. This is really helpful because it means other plants can use these bits to grow.
  2. Plant Food: The bits broken down by saprophytic fungi become food for other plants. They’re like nature’s recycling crew, turning old stuff into new food.
  3. Mushrooms: Some of these fungi become tasty mushrooms, which can be eaten (though some can be dangerous). People and animals enjoy them as food.
  4. Fermentation: Single-celled fungi like yeast are important for making things like bread and alcohol. They’re like the secret ingredient that helps with the cooking process.

Saprophytic Bacteria: There are also bacteria that do the same kind of work. They grow on decaying stuff and help break it down. They’re found in rotting wood, decaying plants and animals, and even in stagnant water.

These bacteria have important jobs too:

  1. Organic Manure: They’re used on farms to turn complex stuff like dung into simple manure that helps plants grow.
  2. Food Spoilage: While they’re good at breaking things down, they can also spoil food, making it go bad faster.
  3. Fermentation and More: These bacteria are also used in fermentation, which is important for making things like vinegar.

So, both saprophytic fungi and bacteria are like nature’s clean-up crew, breaking down old stuff and helping in different ways to keep things in balance.

3. Parasitic Nutrition

Parasitic nutrition is like a one-sided meal deal in nature. Let’s break it down:

Parasite and Host: Imagine one creature depending on another for its meals. The creature getting the food is called the “parasite,” and the one giving the food is the “host.”

How It Works: The parasite gets its food from the host, but the host doesn’t benefit. In fact, the host might get harmed by this arrangement.

Examples of Parasites: Some common examples of parasites are mosquitoes (that give us diseases like malaria), ticks, bed bugs, and tapeworms (that live in our intestines). Even certain plants can be parasites, like dodder and mistletoe.

Types of Parasitic Nutrition:

  1. Total Parasites (Endo-Parasites): These parasites completely depend on the host for everything – food, water, and even a place to live. They can’t survive on their own. For example, tapeworms live inside animals’ intestines.
  2. Partial Parasites: These parasites mainly rely on the host for food, but they don’t need to live inside the host. An example is a mosquito that sucks blood but doesn’t live in the host.

Ecto-Parasites and Endo-Parasites: Some parasites live outside the host’s body (like ticks) and are called ecto-parasites. Others live inside (like tapeworms in our intestines) and are called endo-parasites.

Parasitic nutrition is like a one-way street – the parasite gets its meals, but the host doesn’t get anything good in return.

Types of Heterotrophs Based on Food Habits

Heterotrophs, or creatures that need to eat to get their energy, are divided into four types based on what they eat and where they are in the food chain. These types are herbivores, carnivores, omnivores, and detritivores.

  1. Herbivores: These animals eat plants and algae. They are like the first group of eaters and are at the second level in the food chain.Examples: Deer, cow, and buffalo.
  2. Carnivores: These creatures eat meat and prey on herbivores. They’re like the second group of eaters and are at the third level in the food chain.Examples: Tiger, wolf, and crocodile.
  3. Omnivores: Omnivores eat both plants and meat. They’re also at the third level, like the carnivores.Examples: Humans, bears, and foxes.
  4. Detritivores (Decomposers): These special beings feed on leftovers, like dead plants, animals, and waste. They help keep the environment clean and healthy.Examples: Bacteria, fungi, worms, and insects.

So, different types of heterotrophs eat different things and play different roles in keeping nature in balance.

Types of Heterotrophs Based on electron source

There are different types of heterotrophs based on how they get their energy and food. Let’s talk about two main types:

  1. Organotrophs: These are heterotrophs that use organic compounds for energy and food. They get their energy by breaking down organic substances through a process called internal respiration. In this process, the organic compound provides an electron that goes through a chain of reactions to create ATP, which is like the energy currency for cells. Organotrophs include animals and some types of bacteria. Some of these bacteria can live with or without oxygen (aerobic or anaerobic).
  2. Lithotrophs: These heterotrophs get their energy from inorganic compounds or geological processes. Unlike organotrophs, they use things like elemental sulfur and gases as sources of electrons. These compounds might not give as much energy as organic ones, so most lithotrophs are smaller bacteria. They take these electrons and convert them into ATP through a special process. The interesting thing is that we only know of unicellular organisms that use this method. Some larger organisms might team up with these unicellular ones to get energy. You can find many lithotrophs in places like the ocean floor or underground water sources where these special compounds are available.

So, there are organotrophs that use organic stuff for energy, and lithotrophs that use inorganic things or special processes to get their energy.

Examples of Heterotrophs

Let’s talk about some examples of heterotrophs, which are living things that need to get their food and energy from other sources:

  1. Fungi: Fungi are a type of living thing that relies on dead and decaying matter for their food and energy. They’re like nature’s recyclers! Fungi break down complex stuff and turn it into simpler molecules. You can find them in dry places, like soil, where there’s a lot of dead stuff. Some fungi can live with or without oxygen and get different amounts of energy from their food.
  2. Photoheterotrophic Cyanobacteria: These are tiny organisms that are really good at using sunlight to make energy. They can’t use carbon dioxide like some other plants, but they use the sun’s energy to do some cool chemistry. You can find them in watery places where they eat organic stuff made by other tiny water-living organisms. People study them because they’re good at making energy from sunlight.
  3. Iron-Reducing Bacteria: These are special bacteria that use iron to get energy. They take a kind of iron and change it into a different kind, and that change gives them energy. They’re like little metal-eaters! These bacteria can be used to clean up places with too much metal pollution. They’re often found in tough environments where there are certain kinds of chemicals.
  4. Animals: Animals are a big group of heterotrophs, and they’re the ones we’re most familiar with. From tiny insects to big mammals, animals need to eat other things to get their energy and food. Some animals, like herbivores, eat plants and tiny water plants. Others, like carnivores, eat other animals. It’s like a big food chain! Animals take the stuff they eat and break it down into simpler bits to use for energy and growth.

So, these are some examples of different kinds of heterotrophs that get their energy and food from other sources in various ways.

Role of Heterotrophs in the Ecosystem or Food Chain

Let’s talk about how heterotrophs fit into the food chain, which is like a big cycle of eating and getting energy:

Heterotrophs are a big group of living things in the food chain. They can be found at different levels in this cycle.

  • First Level: Some heterotrophs are at the first level. They eat plants and other things that can make their own food (autotrophs). This is like the beginning of the energy transfer.
  • Second Level: The next group of heterotrophs is at the second level. They eat the ones from the first level. They’re like the direct eaters of the ones that make their own food. This helps move energy from one level to another.
  • Third Level: Then there are other heterotrophs at the third level. These ones eat the ones from the second level. They’re a bit more complex and they feed on organic stuff. It’s like a chain of eating!
  • Decomposers: There’s another important group of heterotrophs. They’re called decomposers. They live higher up in the chain. These special organisms eat things that are dead and rotting. They help break down these things and release important stuff back into the environment.

At each step in this chain, some energy gets passed along. But not all of it goes to the next level. About 10% of the energy moves on, and the rest stays as the mass of the living things. It’s like a big circle of eating and using energy!

So, heterotrophs are all around in the food chain, from eating autotrophs to eating other heterotrophs, and even cleaning up by breaking down dead stuff. They play a big role in how energy moves through nature.

Plants and Animal Heterotrophs

There are different ways plants and animals get their food. Let’s talk about them:

Plants – Heterotrophs: While most plants make their own food through photosynthesis, some plants can’t do that. These are called heterotrophs. There are two kinds – parasitic plants and saprophytic plants.

  • Parasitic plants: These plants live off other plants. They use another plant as a host, like a home, to get their food.
  • Saprophytic plants: These plants eat dead stuff. They feed on things that are rotting and no longer alive.

Animals – Heterotrophs: Animals are also heterotrophs. Unlike plants, they can’t make their own food through photosynthesis. Instead, they have to find their food from other sources. Animals can be categorized based on what they eat.

  • Detritivores: These animals eat decaying plants and animals, like nature’s cleaners.
  • Saprophytes: These are organisms that eat dead things, just like saprophytic plants.
  • Organotrophs and Lithotrophs: These are different types of animals based on how they get their energy. Organotrophs use carbon compounds from plants and animals, while lithotrophs use inorganic compounds like sulfur.

So, plants and animals have different ways of being heterotrophs, which means they need to find their food instead of making it themselves.


What is a heterotroph?

A heterotroph is an organism that cannot make its own food and relies on other sources for nutrition.

How do heterotrophs get their food?

Heterotrophs get their food by consuming other living organisms or organic matter.

What’s the difference between heterotrophs and autotrophs?

Heterotrophs rely on external sources for food, while autotrophs make their own food through processes like photosynthesis.

What are some examples of heterotrophs?

Animals, fungi, some bacteria, and many protists are examples of heterotrophs.

Do all heterotrophs eat the same things?

No, heterotrophs have diverse diets. Some eat plants, some eat other animals, and some consume decaying matter.

How do herbivores, carnivores, and omnivores fit into heterotrophic nutrition?

Herbivores eat plants, carnivores eat other animals, and omnivores eat both plants and animals.

What is saprophytic nutrition?

Saprophytic nutrition is a type of heterotrophic nutrition where organisms feed on dead and decaying organic matter.

How do parasites get their food?

Parasites depend on other organisms (hosts) for their food, often causing harm to the host in the process.

Are humans heterotrophs?

Yes, humans are heterotrophs because we need to eat food to obtain the energy and nutrients we require.

Why are heterotrophs important in ecosystems?

Heterotrophs help in recycling nutrients by consuming and breaking down organic matter, playing a crucial role in energy flow and maintaining balance in food chains.



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What is a digital colony counter? Why do Laboratory incubators need CO2? What is Karyotyping? What are the scope of Microbiology? What is DNA Library? What is Simple Staining? What is Negative Staining? What is Western Blot? What are Transgenic Plants? Breakthrough Discovery: Crystal Cells in Fruit Flies Key to Oxygen Transport
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