Normally krili are found in concentrations of 10 to 100
individuals per cubic meter. When they gather together in
a defensive group called a swarm they may number up to
100,000 per cubic meter. A singie swarm can be as large
as 450 square kilometers and contain up to 200 miliion
metric tons of krili. It can turn the surface of the ocean
pink. Some swarms are large enough to be seen from
space. Krill are so abundant that they weigh more than all
of the people on Earth