Trophic level

Trophic levels categorize organisms into different levels of the food chain. The first trophic level are producers, or autotrophs.

Trophic Level Media

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  First trophic level. The plants in this image, and the algae and phytoplankton in the lake, are primary producers. They take nutrients from the soil or the water, and manufacture their own food by photosynthesis, using energy from the sun.

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  Consumer categories based on material eaten (plant: green shades are live, brown shades are dead; animal: red shades are live, purple shades are dead; or particulate: grey shades) and feeding strategy (gatherer: lighter shade of each color; miner: darker shade of each color)

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  An energy pyramid illustrates how much energy is needed as it flows upward to support the next trophic level. Only about 10% of the energy transferred between each trophic level is converted to biomass.

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  Killer whales (orca) are apex predators but they are divided into separate populations that hunt specific prey, such as tuna, small sharks, and seals.

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  The mean trophic level of the world fisheries catch has steadily declined because many high trophic level fish, such as this tuna, have been overfished.

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  Second trophic levelRabbits eat plants at the first trophic level, so they are primary consumers.

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  Third trophic levelFoxes eat rabbits at the second trophic level, so they are secondary consumers.

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  Fourth trophic levelGolden eagles eat foxes at the third trophic level, so they are tertiary consumers.

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  DecomposersThe fungi on this tree feed on dead matter, converting it back to nutrients that primary producers can use.