Question

click on the organism in the food web who is sometimes a quaternary consumer and sometimes a tertiary consumer.

Explanation:

A quaternary consumer is at the fourth - trophic level and a tertiary consumer is at the third - trophic level. In the food web, the snake can feed on the frog (making it a tertiary consumer in that chain) and also be preyed upon by the eagle while preying on the bird which makes it a quaternary consumer in some food chains.

Answer:

Snake