Animals mix the oceans
Animals and other organisms are responsible for one-third of the mixing of the ocean, without which the sea would stagnate. The oceans on Earth are estimated to have a volume of 1.332 billion cubic kilometers (0.3 billion cubic miles )
Biosphere mixing appears to provide about one third the power required to bring the deep, cold waters of the world ocean to the surface, which in turn completes the ocean's conveyor belt circulation critical to the global climate system.
Energy put into the oceans by small animals such as krill is a significant component of the total contributed by all swimming creatures, adding up to a force comparable to that of winds and tides.
The research suggests that scientists modeling global climate processes may need to add the contribution of such swimmers to the mix.
Vertical transport
The two most important elements, which are abundant in the deep but limited higher up, are nitrogen and iron, which plants need to convert solar energy into energy-rich chemicals like carbohydrates that fuel higher forms of life.
Big animals such as whales can transport nutrients with the turbulent wakes created by their movement. But smaller animals like krill likely can move things around too, especially when they move in groups in a uniform "mat," moving down hundreds of feet or meters during the day, and back up again at night.