So it is the energy produced by these algae that forms the basis of the food pyramid in the ocean. (from Duxbury and Duxbury, 1994, An Introduction to the World's Oceans). The pyramid represents energy in the ocean. The widest part is the microscopic algae.Perhaps I should add here that plankton are the very small drifters in the ocean. Phytoplankton are the plants or algae, and zooplankton are the animals.). Note also that at the bottom there are 1000 energy units available. The next level up is the herbivorous (plant eating) zooplankton.