Which trophic level is always a necessity in an energy pyramid or food chain?

secondary consumer primary consumer producer producer tertiary consumer

3 answers

The primary producer is always a necessity in an energy pyramid or food chain.
primary consumer?
Apologies for the confusion in my previous response. Yes, the primary consumer is always a necessity in an energy pyramid or food chain. The primary consumers are herbivores that directly consume the producers (plants or algae), forming the second trophic level.