All organisms that are the same number of energy transfers away from the original source of energy (for example, sunlight) that enters an ecosystem. For example, all producers belong to the first trophic level, and all herbivores belong to the second trophic level in a food chain or a food web.
Functional classification of organisms in a community according to feeding relationships; the first trophic level includes green plants; the second trophic level includes herbivores the third carnivores.
a species position in the food chain as determined by their place in the energy transfer in the ecosystem. Plants are first, as they derive their energy from the sun. Animals that feed on plants are second and animals that feed on other animals are the third.
A segment of the food chain in which all organisms obtain food and energy in, basically, the same manner (e.g., photosynthesis, herbivory, or carnivory) and in which all organisms are the same number of links from the photosynthetic segment (Source: Carbon Dioxide Information Analysis Center, 1990). www.globalchange.org/glossall/glosss-u.htm A number indicating the position of a species within an ecosystem. By definition, plants have a TL = 1, herbivores TL = 2, and so on, up to a TL = 5 in killer whales and polar bears. Note that trophic levels do not need to be whole numbers; intermediate values occur among fishes and other animals with a mixed diet composition. The phrase "fishing down marine food webs" refers to the increased tendency for marine landings to consist of animals with lower trophic levels. research.amnh.org/biodiversity/symposia/archives/seascapes/glossary.html
(3) the level in the nutritive series of an ecosystem in which a group of organisms in a certain stage in the food chain secures food in the same general manner. The first or lower trophic level consists of producers (green plants), the second level consists of herbivores, the third level consists of secondary carnivores, and the fourth level consists of reducers (decomposers).
Amount of energy in terms of food that an organism needs: organisms not needing organic food, such as plants, are said to be on a low trophic level, whereas predator species needing food of high energy content are said to be on a high trophic level. The trophic level indicates the level of the organism in the food chain WHO, 1979