A trophic level is the position an organism occupies in a food chain, based on how it gets its energy.• Trophic level 1: producers
• Trophic level 2: primary consumers
• Trophic level 3: secondary consumers
• Trophic level 4: tertiary consumersArrows in a food chain show the direction of energy transfer, from the organism that is eaten to the organism that eats it.In real ecosystems, feeding relationships form a food web, and one species may feed at more than one trophic level. A fox eating rabbits (grass → rabbit → fox) is a secondary consumer, but a fox eating a shrew that ate beetles that ate plants is a tertiary consumer. Omnivores, such as humans, are primary consumers when they eat plants and secondary consumers when they eat meat from herbivores.At each transfer from one trophic level to the next, much of the energy is lost to the environment, mainly as heat from respiration and in parts that are not eaten or digested. So less energy is available at each higher level. This is why food chains rarely have more than four or five trophic levels: too little energy is left to support another population.Example: In the chain oak tree → caterpillar → blue tit → sparrowhawk, the oak is at trophic level 1 and the sparrowhawk is at trophic level 4.Decomposers are not given a single trophic level, because they feed on dead material from every level.
• Trophic level 2: primary consumers
• Trophic level 3: secondary consumers
• Trophic level 4: tertiary consumersArrows in a food chain show the direction of energy transfer, from the organism that is eaten to the organism that eats it.In real ecosystems, feeding relationships form a food web, and one species may feed at more than one trophic level. A fox eating rabbits (grass → rabbit → fox) is a secondary consumer, but a fox eating a shrew that ate beetles that ate plants is a tertiary consumer. Omnivores, such as humans, are primary consumers when they eat plants and secondary consumers when they eat meat from herbivores.At each transfer from one trophic level to the next, much of the energy is lost to the environment, mainly as heat from respiration and in parts that are not eaten or digested. So less energy is available at each higher level. This is why food chains rarely have more than four or five trophic levels: too little energy is left to support another population.Example: In the chain oak tree → caterpillar → blue tit → sparrowhawk, the oak is at trophic level 1 and the sparrowhawk is at trophic level 4.Decomposers are not given a single trophic level, because they feed on dead material from every level.