In subtropical, nutrient-poor warm waters, transfer of energy from small phytoplankton (< 2pm) to higher predators takes a larger number of steps and therefore provides a longer and lower flow of organic carbon. In contrast, in nutrient-rich, cooler waters with larger phytoplankton (> 20 pm), the pathway is shorter and energy transfer is fast. Found throughout the water column, microscopic and larger animals and juvenile stages offish, crustaceans, molluscs and other benthic animals which feed on phytoplankton form the group known as zoo-plankton.