No, organisms do not always stay in the same trophic level throughout their lives. A trophic level is a position in the food chain that is defined by how an organism obtains its energy. For example, primary producers, such as plants, occupy the first trophic level, while herbivores are in the second level and carnivores in the third or higher levels.
Several factors can lead to changes in an organism’s trophic level. For instance, some animals undergo changes in diet based on their life stage. A classic example is the tadpole, which is a herbivore as a larva but becomes a carnivorous frog as an adult. Similarly, certain fish species may eat different foods during their development, moving between trophic levels as they grow.
Environmental factors also play a role in altering an organism’s trophic level. Changes in food availability, competition, and habitat can influence what an organism eats and, consequently, its position in the food web. For example, a scarcity of prey may push a carnivorous fish to feed on herbivorous organisms if it adapts to do so.
In summary, while many organisms occupy a specific trophic level during their lifetime, changes in diet or environmental conditions can cause them to move to different levels in the food web.