page_title: Largest organisms
section_title: Heaviest living animals
hierarchical_section_title: Largest organisms / Animals / Heaviest living animals
caption_attribution_description: Infographic from 'Sizing ocean giants: patterns of intraspecific size variation in marine megafauna'.
context_page_description: The largest organisms now found on Earth can be determined according to various aspects of an organism's size, such as: mass, volume, area, length, height, or even genome size. Some organisms group together to form a superorganism, but such are not classed as single large organisms. The Great Barrier Reef is the world's largest structure composed of living entities, stretching 2,000 km, but contains many organisms of many types of species.
  The organism sizes listed are frequently considered "outsized" and are not in the normal size range for the respective group.
  If considered singular entities, the largest organisms are clonal colonies which can spread over large areas. Pando, a clonal colony of the quaking aspen tree, is widely considered to be the largest such organism by mass. Even if such colonies are excluded, trees retain their dominance of this listing, with the giant sequoia being the most massive tree. In 2006 a huge clonal colony of Posidonia oceanica was discovered south of the island of Ibiza. At 8 kilometres across, and estimated at around 100,000 years old, it may be one of the largest and oldest clonal colonies on Earth.
context_section_description: The heaviest living animals are all cetaceans, and thus also the largest living mammals. Since no scale can accommodate the whole body of a large whale, most whales have been weighed by parts.
caption: Infographic showing the size of marine megafauna.
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