Autotrophs are usually plants; they are also called "self feeders" or "primary producers". Heterotrophs survive by feeding on organic matter produced by or available in other organisms. There are two types of heterotrophs:. Autotrophs do not depend on other organism for their food. They are the primary producer and are placed first in the food chain. Heterotrophs that depend on autotrophs and other heterotrophs for their energy level are placed next on the food chain.
Herbivores that feed on autotrophs are placed in the second trophic level. Carnivores that eat meat and omnivores that eat all types of organisms are placed next in the trophic level.
Share this comparison:. Autotrophs make food for their own use, but they make enough to support other life as well. Almost all other organisms depend absolutely on these three groups for the food they produce.
The producers , as autotrophs are also known, begin food chains which feed all life. Food chains will be discussed in the " Food Chains and Food Webs " concept. Heterotrophs cannot make their own food, so they must eat or absorb it. For this reason, heterotrophs are also known as consumers. Consumers include all animals and fungi and many protists and bacteria. They may consume autotrophs or other heterotrophs or organic molecules from other organisms.
Heterotrophs show great diversity and may appear far more fascinating than producers. But heterotrophs are limited by our utter dependence on those autotrophs that originally made our food. If plants, algae, and autotrophic bacteria vanished from earth, animals, fungi, and other heterotrophs would soon disappear as well.
All life requires a constant input of energy. Only autotrophs can transform that ultimate, solar source into the chemical energy in food that powers life, as shown in Figure below.
Photosynthetic autotrophs, which make food using the energy in sunlight, include a plants, b algae, and c certain bacteria. Photosynthesis provides over 99 percent of the energy for life on earth.
A much smaller group of autotrophs - mostly bacteria in dark or low-oxygen environments - produce food using the chemical energy stored in inorganic molecules such as hydrogen sulfide, ammonia, or methane. While photosynthesis transforms light energy to chemical energy, this alternate method of making food transfers chemical energy from inorganic to organic molecules. It is therefore called chemosynthesis , and is characteristic of the tubeworms shown in Figure below.
Some scientists think that chemosynthesis may support life below the surface of Mars, Jupiter's moon, Europa, and other planets as well. Ecosystems based on chemosynthesis may seem rare and exotic, but they too illustrate the absolute dependence of heterotrophs on autotrophs for food.
A food chain shows how energy and matter flow from producers to consumers. Matter is recycled, but energy must keep flowing into the system.
Where does this energy come from? Though this food chains "ends" with decomposers, do decomposers, in fact, digest matter from each level of the food chain? Tubeworms deep in the Galapagos Rift get their energy from chemosynthetic bacteria living within their tissues. There are two subcategories of heterotrophs: photoheterotrophs and chemoheterotrophs.
Photoheterotrophs are organisms that get their energy from light, but must still consume carbon from other organisms, as they cannot utilize carbon dioxide from the air. Chemoheterotrophs, by contrast, get both their energy and carbon from other organisms. A major difference between autotrophs and heterotrophs is that the former are able to make their own food by photosynthesis whereas the latter cannot.
Photosynthesis is a process that involves making glucose a sugar and oxygen from water and carbon dioxide using energy from sunlight. Autotrophs are able to manufacture energy from the sun, but heterotrophs must rely on other organisms for energy. Another major difference between autotrophs and heterotrophs is that autotrophs have an important pigment called chlorophyll , which enables them to capture the energy of sunlight during photosynthesis, whereas heterotrophs do not.
Without this pigment, photosynthesis could not occur. Heterotrophs benefit from photosynthesis in a variety of ways.
They depend on the process for oxygen, which is produced as a byproduct during photosynthesis. Moreover, photosynthesis sustains the autotrophs that heterotrophs depend on to survive. While meat-eating carnivores may not directly depend on photosynthetic plants to survive, they do depend on other animals that consume photosynthetic plants as a food source. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher.
They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.
0コメント