Sea microbes 'equal 240 billion elephants'

New research has shown marine bugs are far more abundant than was previously thought and make up 50 per cent to 90 per cent of all the biological material, or "biomass", in the oceans.

Experts estimate their numbers at around 10 to the power of 30 – or 1,000 times a billion times a billion times a billion.

Their combined weight matches that of 240 billion African elephants – or 35 elephants-worth of microbes for every human being on the planet, it was claimed.

The true extent of the marine microbe population is only now being revealed by the Census of Marine Life, a huge project to survey life in the oceans involving more than 2,000 scientists.

In the 1950s, it was estimated that about 100,000 microbial cells inhabited a litre of sea water. Today, the same volume of water is believed to hold more than a billion micro-organisms. A gram of ocean floor mud holds about the same.

"In no other realm of ocean life has the magnitude of census discovery been as extensive as in the world of microbes," said Dr Mitch Sogin, from the Marine Biological Laboratory at Woods Hole, Massachusetts, US,

who heads the International census of Marine Microbes.

"Scientists are discovering and describing an astonishing world of marine microbial diversity and abundance."