Whales have roamed the oceans for millions of years. In fact, the two living suborders of whales, i.e. Mysticetes (baleen whales) and Odontocetes (toothed whales), have existed for approximately 20 million years. The evolution of evolving such enormous bodies has required plentiful food resources which the oceans have certainly had to offer. Only in recent decades have whales been faced with such a ferocious competitor for food resources as human fishing fleets.
A common misconception is that the whales, in particular the large ones, eat too much of the available resources. While whales certainly eat much their large bodies would not have been able to evolve if it were “too much”. The smaller ones would have survived and multiplied while the big ones would have vanished.
All whales, small and large, necessarily contribute to the ecosystem in which they live. They must, otherwise their future wouldn’t be bright.
But how so?
Whales, like other organisms, feed on other organisms transforming them into a new type of biomass, namely whale tissue (e.g. blubber, muscles, bones, connective tissue etc.) and benefits the whale while it lives. After the whale dies the entire biomass is returned back into the food web via decomposers as well as carnivores and other scavengers.
In shallow waters the whale carcass is consumed quite quickly by various animals and bacteria. In deeper waters, around or below a depth of 2000 m (6600 ft), a whale carcass is called a “whale fall”. Under such conditions the carcass will create a complex and localized ecosystem, benefiting deep-water organisms for decades.
What about when they live and breathe?
Whales contribute to the food web which they belong to throughout their lives for as long as they eat they will poop! No different from the cattle that return nutrients back to the grass with their feces while ruminating peacefully through their grass planes, whales cultivate the upper layers of the sea with vital nutrients from their feces. But not only do they recycle nutrients, they also bring nutrients up to the upper layers; a phenomena called the Whale Pump.
All whales (i.e. whales, dolphins and porpoises) must dive to find and catch prey, often reaching great depths. When a whale reaches the surface again to breathe they generally defecate large swarms and sometimes chunks of nutritious feces. Photosynthesizing phytoplankton, which can only survive in the upper sunlit layers of the ocean (the euphotic zone), needs essential nutrients such as nitrogen, phosphorous and iron to multiply and produce organic material through photosynthesis. Large concentrations of these nutrients, particularly nitrogen and iron, are found in the whale feces.
Phytoplankton are small single celled organisms that live in salt and fresh waters. They are the bases of the ocean and freshwater food chains just as plants are on land. They produce oxygen as a byproduct when converting inorganic material into organic (i.e. sugars), both of which are vital for all animals.
Recent study has shown the importance of whale feces to sustain local krill populations in the Antarctic; an important reminder that whales have evolved according to their environment. These giants are not off beat with nature, they live in harmony with it!
Edda Elísabet Magnúsdóttir
Marine Biologist and a whale specialist at the University of Iceland
Edits by Martin Swift