Wednesday Word of the Week: Autotroph

The MWW Blog is launching a new series called “Wednesday Word of the Week.” This feature will contribute to our ongoing work educating the public about geo-literacy–the ability to use geographic knowledge to make informed decisions about the dynamic world we live in. Geo-literacy is a relevant, applicable, and global tool; it is a communicative bridge between the peoples, places and possibilities of our earth.

2011-09-06_1195235.JPGAutotroph: [aw-tuh-trof, -trohf] [environmental geography]
Noun: An autotroph is an organism that can produce its own food using light, water, carbon dioxide, or other chemicals. Because autotrophs produce their own food, they are sometimes called producers.

Plants are the most familiar type of autotroph, but there are many different kinds of autotrophic organisms. Algae, which live in water and whose larger forms are known as seaweed, is autotrophic. Phytoplankton, tiny organisms that live in the ocean, are autotrophs. Some types of bacteria are autotrophs.

What about carnivorous plants? How would you classify the venus flytrap–is it an autotroph because it is a plant? Or is it a heterotroph? (HEH-tuh-roh-trohf) noun. An organism that cannot make its own nutrients and must rely on other organisms for food.


Some rare autotrophs produce food through a process called chemosynthesis, rather than through photosynthesis. Autotrophs that perform chemosynthesis do not use energy from the sun to produce food. Instead, they make food using energy from chemical reactions, often combining hydrogen sulfide or methane with oxygen.

Organisms that use chemosynthesis live in extreme environments, where the toxic chemicals needed for oxidation are found. For example, bacteria living in active volcanoes oxidize sulfur to produce their own food. At Yellowstone National Park in the U.S. states of Wyoming, Idaho, and Montana, bacteria capable of chemosynthesis have been found in hot springs.

2011-09-19_1204675.JPGBacteria that live in the deep ocean, near hydrothermal vents, also produce food through chemosynthesis. A hydrothermal vent is a narrow crack in the seafloor. Seawater seeps down through the crack into hot, partly melted rock below. The boiling-hot water then circulates back up into the ocean, loaded with minerals from the hot rock. These minerals include hydrogen sulfide, which the bacteria use in chemosynthesis. (Source:

The Wednesday Word of the Week is just one way to start expanding the breadth of your geographic vocabulary. Some words you’ll recognize, and some will be new. Regardless of whether you know the word or not, we at National Geographic Education challenge you to use our words of the week.  Whether in the classroom, in everyday conversation, through the arts, or simply by checking out our provided links, we encourage you to make great use of our words in creative ways!

As always, we want to hear your comments, questions, successes and more! E-mail us at and share your Geo-Literacy stories and photos.

–Julia from My Wonderful World

2 thoughts on “Wednesday Word of the Week: Autotroph

  1. Thanks for your feedback Bijay–let me know if you think of other great biology-science vocabulary words that we can feature. I would also love to hear any other ideas you may have on how we can better incorporate science education (biology) into the blog.

Leave a Reply