How would the energy (calories) needs change if secondary consumers were removed from the pyramid?

The answer has to do with trophic levels. As you probably know, the organisms at the base of the food chain are photosynthetic; plants on land and phytoplankton (algae) in the oceans. These organisms are called the producers, and they get their energy directly from sunlight and inorganic nutrients. The organisms that eat the producers are the primary consumers. They tend to be small in size and there are many of them. The primary consumers are herbivores (vegetarians). The organisms that eat the primary consumers are meat eaters (carnivores) and are called the secondary consumers. The secondary consumers tend to be larger and fewer in number. This continues on, all the way up to the top of the food chain. About 50% of the energy (possibly as much as 90%) in food is lost at each trophic level when an organism is eaten, so it is less efficient to be a higher order consumer than a primary consumer. Therefore, the energy transfer from one trophic level to the next, up the food chain, is like a pyramid; wider at the base and narrower at the top. Because of this inefficiency, there is only enough food for a few top level consumers, but there is lots of food for herbivores lower down on the food chain. There are fewer consumers than producers.