SAVING ANTARCTICA

The Antarctic Food Web is relatively simple compared to ecosystems in other parts of the world. There are fewer different species, but greater numbers of them. The second most numerous large mammal in the world (after man) is the crab-eater seal, an archetypal Antarctic animal.

A key part of the Antarctic food web are krill small shrimp-like crustaceans that the great majority of Antarctic animals, seal, whales, penguins and other birds, fish etc. feed upon.

Big floes have little floes all around about 'em
     And all the yellow diatoms couldn't do without 'em.
Forty million shrimplets feed upon the latter,
     And they make the penguin and the seals and whales
                                                                  Much fatter.

Thomas Griffith Taylor - geologist on Scott's 1909-11 expedition

Whales are the largest animals ever to have lived, larger even than the largest dinosaurs. There are two reasons that they have managed to attain such enormous size - well over a hundred tonnes for the largest blue whales and nearing this amount for some other whale species.

1/ They live in the oceans and so the buoyancy of the water can support their great bulk rather than having to propped up and moved on land by legs and muscles. Like most other animals, the density of a whale is very close to that of water.

2/ Whales tap the food chain low down - close to the producers, there are few steps and so little energy is lost meaning more is available to the whales, so they are able to grow to enormous sizes. The alternative consequence of this is that the higher up a food chain you get, the lower the biomass of animals (that is number of animals multiplied by their weight) because there are more steps and so more energy is lost.