Gargantuan whales and hefty cephalopods are typically thought of as the classic marine mammoths, but they might have to make way for the mighty microbes, which constitute 50 to 90 percent of the oceans' total biomass, according to newly released data.

These tiny creatures can join together to create some of the largest masses of life on the planet, and researchers working on the decade-long Census of Marine Life project found one such seafloor mat off the Pacific coast of South America that is roughly the size of Greece.

A single liter of seawater, once thought to contain about 100,000 microbes, can actually hold more than one billion microorganisms, the census scientists reported. But these small creatures don't just live in the water column or on the seafloor. Large communities of microscopic animals have even been discovered more than one thousand meters beneath the seafloor. Some of these deep burrowers, such as loriciferans, are only a quarter of a millimeter long.

"Far from being a lifeless desert, the deep sea rivals such highly diverse ecosystems as tropical rainforests and coral reefs," Pedro Martinez Arbizu, of the German Center for Marine Biodiversity Research and leader of the Census of the Diversity of Abyssal Marine Life, said in a prepared statement.