In a typical aquatic food web, which trophic levels can fishes occupy?

• A. Only secondary consumers
• B. Only primary consumers
• C. Only producers
• D. Both secondary and tertiary consumers

Answer: (D)

Verified step by step guidance

1. Understand the concept of trophic levels: Trophic levels represent the position an organism occupies in a food web, such as producers (autotrophs), primary consumers (herbivores), secondary consumers (carnivores that eat herbivores), and tertiary consumers (carnivores that eat other carnivores).
2. Recognize that fishes are heterotrophs, meaning they cannot produce their own food and must consume other organisms for energy. This excludes them from being producers.
3. Identify that fishes can occupy different trophic levels depending on their diet. For example, herbivorous fishes that feed on algae or phytoplankton are primary consumers.
4. Understand that carnivorous fishes that feed on herbivorous organisms (e.g., zooplankton or smaller fishes) are secondary consumers, while those that feed on other carnivorous fishes are tertiary consumers.
5. Conclude that fishes can occupy both secondary and tertiary consumer levels in an aquatic food web, depending on their specific feeding behavior and diet.