Colinvaux spent a lot of time researching thermodynamics, so his reasoning has to do with trophic levels within an ecosystem. Basically, the second law of thermodynamics says that when energy is transferred, there will be less energy available at the end of the transfer process due to entropy.
In a food web, plants begin by harnessing energy from the sun. Then herbivores eat plants, then secondary carnivores eat herbivores, and then apex carnivores (the biggest, fiercest type) eat them. At every step of the process, available energy and heat are lost. That means to support even one apex carnivore, the ecosystem must be able to support several secondary carnivores, which means supporting many herbivores, which means having a ton of plants. It's almost like a pyramid, with the big fierce animals at the top (or apex), which is where the term apex predator comes from.
In a food web, plants begin by harnessing energy from the sun. Then herbivores eat plants, then secondary carnivores eat herbivores, and then apex carnivores (the biggest, fiercest type) eat them. At every step of the process, available energy and heat are lost. That means to support even one apex carnivore, the ecosystem must be able to support several secondary carnivores, which means supporting many herbivores, which means having a ton of plants. It's almost like a pyramid, with the big fierce animals at the top (or apex), which is where the term apex predator comes from.