Describe the open-ocean planktonic food chain, and elaborate on why its supports few large animals. ...

The nutrient-poor open ocean food chain starts with cyanobacteria and nanoplankton. They are consumed by microzooplankton that include foraminiferans and radiolarians which in turn are consumed by copepods. The copepods are preyed on by krill, shrimp, and small fish. These medium-sized animals are fed on by squid, larger fish, and whales. Each step represents a tropic level with a 10 percent efficiency. Larger fish are often five to six steps removed from the nutrient limited phytoplankton. At the fifth level only 0.00001 of the original biomass remains.