In the given food chain, which organism is the second order consumer?

In a food chain, organisms are categorized into different trophic levels based on their feeding relationships. Primary producers, such as algae, form the base of the food chain and produce energy through photosynthesis. Primary consumers then feed on these producers. In the case of aquatic ecosystems, mayflies typically represent primary consumers as they feed on algae.

Second-order consumers are organisms that feed on primary consumers. In this chain, stoneflies are considered second-order consumers because they prey on the primary consumers, like mayflies. This feeding relationship confirms that stoneflies occupy a higher trophic level than mayflies.

Humans often act as tertiary consumers as they can eat various organisms, including primary and secondary consumers, depending on their diet. However, in this context, the role of the stoneflies as second-order consumers highlights their direct predation on the primary consumers, thus establishing their position in the food chain. Hence, identifying stoneflies as the second-order consumer illustrates the dynamics of energy transfer through the different levels of an aquatic food web.