What percentage of life is estimated to be in the ocean?

The ocean is home to the greatest diversity of major plant, animal, and microbial groups on Earth.

image of a coral reef

Sometimes referred to as the "rainforests of the sea," coral reefs are some of the most diverse ecosystems in the world.

Covering over 70 percent of the Earth’s surface, the ocean represents our planet’s largest habitat, containing 99 percent of the living space on the planet. This vast area supports the life of nearly 50 percent of all species on Earth.

Scientists are currently conducting the first ever “Census of Marine Life,” to assess and explain the diversity, distribution, and abundance of life in the ocean. Expected to be completed in 2010, this project will be the first to develop a comprehensive global list of all forms of life in the ocean. Additionally, scientists estimate that perhaps a million or more species remain unknown, yet to be discovered.

Biological productivity of the ocean plays a vital role in the global climate and carbon cycle and provides nearly 50 percent of Earth's oxygen and 20 percent of the world's protein supply. Species from the ocean are also potential sources of new medicines.

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