Gereon Janzing, geobotánico y etnobotánico
Gereon Janzing, geobotánico y etnobotánico

Autotroph and heterotroph

Autotroph are the organisms that are able to produce organic substance from anorganic matter. Therefor they need an extern source of energy. The by far most common case is the production of organic substance by photosynthesis, using the sunlight. The organisms are called photoautotroph (phototroph). These are most of the plants and some bacteria.

There are however some bacteria that produce organic substance by chemosynthesis, mainly using sulphur dioxide from sulphuric springs in the sea. These chemoautotroph bacteria are the basis of an ecosystem that is independent of the Sun.

The organisms that are not capable of building up organic matter but have to consume organic matter, are called heterothroph. All the animals (including humans, of course) are heterotroph, they need to eat either plants, fungi, bacteria or animals and their products. Some plants during the evolution have lost their clorophyll and the possibility to make photosynthesis, so they have to live as parasites on other plants, like the different species of broomrape.

French: autotrophe / hétérotrophe