Create a realistic image of a trophic pyramid for a scientific poster

Create a realistic image of a trophic pyramid for a scientific poster. The pyramid should have a transparent PNG background. The top level of the pyramid should contain a single shark as the apex predator. The level below should feature two medium-sized ocean fish: a tuna and a mackerel. The second level should include two smaller marine animals: a sardine and a shrimp. At the base, depict two types of plankton: phytoplankton and zooplankton. The interior of the pyramid should be realistically detailed, but the exterior should be a clean, transparent PNG format.