Largest organisms
This article lists the largest organisms for various types of life and mostly considers extant species,[a] which 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 (such as ants or bees), 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 (1,200 mi) but contains many organisms of many types of species.
When considering 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.[1] Even if such colonies are excluded, trees retain their dominance of this listing, with the giant sequoia being the most massive tree.[2] In 2006 a huge clonal colony of the seagrass Posidonia oceanica was discovered south of the island of Ibiza. At 8 kilometres (5 mi) across, and estimated at 100,000 years old,[3] it may be one of the largest and oldest clonal colonies on Earth.[4][5][6]
Among animals, the largest species are all marine mammals, specifically whales. The blue whale is believed to be the largest animal to have ever lived.[7] The living land animal classification is also dominated by mammals, with the African bush elephant being the largest of these.
The largest known species of bacterium is named Thiomargarita magnifica, which grows to 1 cm (0.39 in) in length,[43] making it visible to the naked eye and also about five thousand times the size of more typical bacteria.[44] BBC News described it as possessing the "size and shape of a human eyelash."[45] Science published a new paper on the bacterium on June 23, 2022.[46] According to a study coauthored by Jean-Marie Volland, a marine biologist and scientist at California's Laboratory for Research in Complex Systems, and an affiliate at the US Department of Energy Joint Genome Institute, T. magnifica can grow up to 2 centimeters long.[47]