Autotroph — Definition & Examples

What Is an Autotroph?

An autotroph is an organism capable of providing energy for itself without consuming other living things. In this case, auto = self, and troph = eat. Basically, these organisms eat things that they produce for themselves. They make food from inorganic substances like light or chemicals.

What Kinds Are There?

A very common type is a photoautotroph. These are photosynthesizing organisms, like plants, algae, and some bacteria. (That's right—photosynthetic bacteria are autotrophs, too.) They obtain their energy from sunlight and convert it into sugars.

A less common type is a chemoautotroph. These organisms can take in surrounding chemicals and use them for energy. For example, aquatic organisms around deep sea vents are never exposed to sunlight. Instead, they take in the super hot carbon compounds released by the vents and convert them into usable organic compounds.

A specific type of chemoautotroph is only found in the domains called bacteria and archaea. These lithoautotrophs use minerals and other inorganic compounds in the environment, such as from rocks and sediment, for energy.

Organisms That Produce Their Own Food

So, first things first, metabolism is the chemical reactions that an organism uses to maintain life. In simpler terms, it's how living things convert food, water, or light into energy to sustain themselves.

Autotrophs are organisms that produce their own food. Plants are the most obvious ones, but some bacteria and algae also fit into this category. Most autotrophs gather solar energy (light) and convert it into chemical energy that they can use. This process is called photosynthesis. This is how plants make complex, organic molecules from simple substances such as carbon dioxide.

These organisms are always found at the bottom of an energy pyramid and are the first step of a food chain.

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Self-feeding Organisms

Before we talk about how autotrophs get their energy, let's first go over what exactly they are.

Like many terms in biology, this word comes from Greek. Take a look at how each part of the word translates.

Okay, so an autotroph is a self-feeding organism. More specifically, it is an organism that does not need to go out and eat other organisms to survive. It gets all of its energy from inorganic substances like sunlight.

Because of this, these organisms are also called primary producers (in contrast to consumers).

Examples include all green plants and any other organism that carries out photosynthesis. (Basic rule: green = autotroph)

Where Do They Get Energy?

So, if autotrophs don't need to go out and eat other organisms to get energy, where does it come from?

Their energy source is the sun.

The sun is required for photosynthesis. This is the process in which plants produce sugar (glucose) that they later metabolize (break down into a usable form).

(Video) Heterotrophs vs. Autotrophs

by MooMoo Math and Science

This video describes the difference between autotrophs and heterotrophs and discusses how they both fit in an energy pyramid. An energy pyramid shows energy flow throughout an ecosystem.

(Video) Learn Biology: Autotrophs vs. Heterotrophs

by mahalodotcom

All organisms need energy, but some lifeforms use different ways of getting that energy. This video gives a quick definition of autotrophs and heterotrophs as well as examples of each.