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 (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.
This article lists the largest species for various types of organisms and mostly considers extant 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 (5 mi) across, and estimated at around 100,000 years old, it may be one of the largest and oldest clonal colonies on Earth.
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. The largest land animal classification is also dominated by mammals, with the African bush elephant being the largest of these.
Main article: List of largest plants
The largest single-stem tree by wood volume and mass is the giant sequoia (Sequoiadendron giganteum), native to Sierra Nevada and California; it typically grows to a height of 70–85 m (230–280 ft) and 5–7 m (16–23 ft) in diameter.
The largest organism in the world, according to mass, is the aspen tree whose colonies of clones can grow up to 8 kilometres (5 mi) long. The largest such colony is Pando, in the Fishlake National Forest in Utah.
Another form of flowering plant that rivals Pando as the largest organism on earth in breadth, if not mass, is the giant marine plant, Posidonia oceanica, discovered in the Mediterranean near the Balearic Islands, Spain. Its length is about 8 km (5 mi). It may also be the oldest living organism in the world, with an estimated age of 100,000 years.
The largest individual flower in the world is Rafflesia arnoldii, while the flowering plant with the largest unbranched inflorescence in the world is Amorphophallus titanum, both are native to Sumatra island of Indonesia.
Green algae are photosynthetic unicellular and multicellular protists that are related to land plants. The thallus of the unicellular mermaid's wineglass, Acetabularia, can grow to several inches (perhaps 0.1 to 0.2 m) in length. The fronds of the similarly unicellular, and invasive Caulerpa taxifolia can grow up to a foot (0.3 m) long.
A member of the infraorder Cetacea, the blue whale (Balaenoptera musculus), is thought to be the largest animal ever to have lived. The maximum recorded weight was 190 tonnes for a specimen measuring 27.6 metres (91 ft), whereas longer ones, up to 33.6 metres (110 ft), have been recorded but not weighed. It is estimated however that this individual could have a mass of 250 tonnes. The title of the longest non-colonial animal is probably owned by Lion's mane jellyfish (36.6m / 120 ft).
The African bush elephant (Loxodonta africana), of the order Proboscidea, is the largest living land animal. A native of various open habitats in sub-Saharan Africa, this elephant is commonly born weighing about 100 kilograms (220 lb). The largest elephant ever recorded was shot in Angola in 1974. It was a male measuring 10.67 metres (35.0 ft) from trunk to tail and 4.17 metres (13.7 ft) lying on its side in a projected line from the highest point of the shoulder to the base of the forefoot, indicating a standing shoulder height of 3.96 metres (13.0 ft). This male had a computed weight of 12.25 tonnes.
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.
|Average total length|
|1||Blue whale||110||190||24 (79)|
|2||North Pacific right whale||60||120||15.5 (51)|
|3||Southern right whale||58||110||15.25 (50)|
|4||Fin whale||57||120||19.5 (64)|
|5||Bowhead whale||54.5||120||15 (49)|
|6||North Atlantic right whale||54||110||15 (49)|
|7||Sperm whale||31.25||57||13.25 (43.5)|
|8||Humpback whale||29||48||13.5 (44)|
|9||Sei whale||22.5||45||14.8 (49)|
|10||Gray whale||19.5||45||13.5 (44)|
The following is a list of the heaviest wild land animals, which are all mammals. The African elephant is now listed as two species, the African bush elephant and the African forest elephant, as they are now generally considered to be two separate species.
|Average total length|
|1||African bush elephant||4.9||10.4||6 (19.7)|
|2||Asian elephant||4.15||8.15||6.8 (22.3)|
|3||African forest elephant||2.7||6.0||6.2 (20.3)|
|4||White rhinoceros[dubious ]||2||4.5||4.4 (14.4)|
|5||Indian rhinoceros||1.9||4.0||4.2 (13.8)|
|7||Javan rhinoceros||1.75||2.3||3.8 (12.5)|
|8||Black rhinoceros||1.1||2.9||4 (13.1)|
Further information: Tunicata
The largest tunicates are Synoicum pulmonaria, found at depths of 20 and 40 metres (66 and 131 ft), and are up to 14 centimetres (6 in) in diameter. It is also present in the northwestern Atlantic Ocean, around the coasts of Greenland and Newfoundland, but is less common here than in the east, and occurs only at depths between 10 and 13 metres (33 and 43 ft).
The largest thaliacean, Pyrosoma atlanticum, is cylindrical and can grow up to 60 cm (2 ft) long and 4–6 cm wide. The constituent zooids form a rigid tube, which may be pale pink, yellowish, or bluish. One end of the tube is narrower and is closed, while the other is open and has a strong diaphragm. The outer surface or test is gelatinised and dimpled with backward-pointing, blunt processes. The individual zooids are up to 8.5 mm (0.33 in) long and have a broad, rounded branchial sac with gill slits. Along the side of the branchial sac runs the endostyle, which produces mucus filters. Water is moved through the gill slits into the centre of the cylinder by cilia pulsating rhythmically. Plankton and other food particles are caught in mucus filters in the processes as the colony is propelled through the water. P. atlanticum is bioluminescent and can generate a brilliant blue-green light when stimulated.
Further information: Leptocardii
The largest lancelets: European lancelet (Branchiostoma lanceolatum) "primitive fish". It can grow up to 6 cm (2.5 in) long.
Main article: List of largest mammals
The blue whale is the largest mammal.
The largest land mammal extant today is the African bush elephant. The largest extinct land mammal known was long considered to be Paraceratherium orgosensis, a rhinoceros relative thought to have stood up to 4.8 m (15.7 ft) tall, measured over 7.4 m (24.3 ft) long and may have weighed about 17 tonnes. In 2015, a study suggested that one example of the proboscidean Palaeoloxodon namadicus may have been the largest land mammal ever, based on extensive research of fragmentary leg bone fossils from one individual, with a maximum estimated size of 22 tonnes.
The Triassic period Lisowicia bojani, from what is now southern Poland, probably was the largest of all non-mammalian synapsids (most of which became extinct 250 million years ago), at 4.5 m (15 ft) and 9 tonnes. However, one study suggested a more conservative weight of 4.87 tonnes to 7.02 tonnes for the adult taxon, with an average body mass of 5.88 tonnes. The largest carnivorous synapsid was Anteosaurus from what is now South Africa during Middle Permian epoch. Anteosaurus was 5–6 m (16–20 ft) long, and weighed about 500–600 kg (1,100–1,300 lb).
Main article: List of largest reptiles
The largest living reptile, a representative of the order Crocodilia, is the saltwater crocodile (Crocodylus porosus) of Southern Asia and Australia, with adult males being typically 3.9–5.5 m (13–18 ft) long. The largest confirmed saltwater crocodile on record was 6.32 m (20.7 ft) long, and weighed about 1,360 kg (3,000 lb). Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than 7 m (23 ft). Also, a living specimen estimated at 7 m (23 ft) and 2,000 kg (4,400 lb) has been accepted by the Guinness Book of World Records. However, due to the difficulty of trapping and measuring a very large living crocodile, the accuracy of these dimensions has yet to be verified. A specimen named Lolong caught alive in the Philippines in 2011 (died February 2013) was found to have measured 6.17 m (20.2 ft) in length.
The Komodo dragon (Varanus komodoensis), also known as the "Komodo monitor", is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, Nusa kode and Padar. A member of the monitor lizard family (Varanidae), it is the largest living species of lizard, growing to a maximum length of more than 3 metres (9.8 feet) in rare cases and weighing up to approximately 166 kilograms (366 pounds).
The following is a list of the heaviest living reptile species ranked by average weight, which is dominated by the crocodilians. Unlike mammals, birds, or fish, the mass of large reptiles is frequently poorly documented and many are subject to conjecture and estimation.
|Average total length|
|1||Saltwater crocodile||450 (990)||2,000 (4,400)||4.5 (14.8)|
|2||Nile crocodile||410 (900)||1,090 (2,400)||4.2 (13.8)|
|3||Orinoco crocodile||380 (840)||1,100 (2,400)||4.1 (13.5)|
|4||Leatherback sea turtle||364 (800)||932 (2,050)||2.0 (6.6)|
|5||Black caiman||350 (770)||1,100 (2,400)||3.9 (12.8)|
|6||American crocodile||335 (739)||1,000 (2,200)||4.0 (13.1)|
|7||Gharial||250 (550)||1,000 (2,200)||4.5 (14.8)|
|8||American alligator||240 (530)||1,000 (2,200)||3.4 (11.2)|
|9||Mugger crocodile||225 (495)||700 (1,500)||3.3 (10.8)|
|10||False gharial||210 (460)||500 (1,100)||4.0 (13.1)|
|11||Aldabra giant tortoise||205 (450)||360 (790)||1.4 (4.6)|
|12||Loggerhead sea turtle||200 (441)||545 (1202)||0.95 (3.2)|
|13||Green sea turtle||190 (418.9)||395 (870.8)||1.12 (3.67)|
|14||Slender-snouted crocodile||180 (400)||325 (720)||3.3 (10.8)|
|15||Galapagos tortoise||175 (390)||417 (919)||1.5 (4.9)|
Main article: Dinosaur size
See also: Largest prehistoric animals
Dinosaurs are now extinct, except for birds, which are theropods.
Main article: List of largest birds
The largest living bird, a member of the Struthioniformes, is the common ostrich (Struthio camelus), from the plains of Africa. A large male ostrich can reach a height of 2.8 m (9.2 ft) and weigh over 156 kg (344 lb). A mass of 200 kg (440 lb) has been cited for the common ostrich but no wild ostriches of this weight have been verified. Eggs laid by the ostrich can weigh 1.4 kg (3.1 lb) and are the largest eggs in the world today.
The largest bird in the fossil record may be the extinct elephant birds (Aepyornithidae) of Madagascar, which were related to the kiwis. Aepyornis exceeded 3 m (9.8 ft) in height and 500 kg (1,100 lb), while Vorombe could reach a similar height and a mass of 732 kg (1,614 lb). The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was Dromornis stirtoni of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae. The largest carnivorous bird was Brontornis, an extinct flightless bird from South America which reached a weight of 350 to 400 kg (770 to 880 lb) and a height of about 2.8 m (9 ft 2 in). The tallest carnivorous bird was Kelenken, which could reach 3 to 3.2 meters in height and 220 to 250 kilograms. The tallest bird ever was the giant moa (Dinornis maximus), part of the moa family of New Zealand that went extinct around 1500 AD. This particular species of moa stood up to 3.7 m (12 ft) tall, but weighed about half as much as a large elephant bird or mihirung due to its comparatively slender frame.
The heaviest bird ever capable of flight was Argentavis magnificens, the largest member of the now extinct family Teratornithidae, found in Miocene-aged fossil beds of Argentina, with a wingspan up to 5.5 m (18 ft), a length of up to 1.25 m (4.1 ft), a height on the ground of up to 1.75 m (5.7 ft) and a body weight of at least 71 kg (157 lb). Pelagornis sandersi is thought to have had an even larger wingspan of about 6.1–7.4 m (20–24 ft), but is only about 22–40 kg (49–88 lb), half the mass of the former.
The following is a list of the heaviest living bird species based on maximum reported or reliable mass, but average weight is also given for comparison. These species are almost all flightless, which allows for these particular birds to have denser bones and heavier bodies. Flightless birds comprise less than 2% of all living bird species.
|Rank||Animal||Binomial Name||Average mass
|Average total length
|1||Common ostrich||Struthio camelus||104 (230)||156.8 (346)||210 (6.9)||No|
|2||Somali ostrich||Struthio molybdophanes||90 (200)||130 (287)||200 (6.6)||No|
|3||Southern cassowary||Casuarius casuarius||45 (99)||85 (190)||155 (5.1)||No|
|4||Northern cassowary||Casuarius unappendiculatus||44 (97)||75 (170)||149 (4.9)||No|
|5||Emu||Dromaius novaehollandiae||33 (73)||70 (150)||153 (5)||No|
|6||Emperor penguin||Aptenodytes forsteri||31.5 (69)||46 (100)||114 (3.7)||No|
|7||Greater rhea||Rhea americana||23 (51)||40 (88)||134 (4.4)||No|
|8||Domestic turkey/wild turkey||Meleagris gallopavo||13.5 (29.8) ||39 (86)||100 - 124.9 (3.3 – 4.1)||Yes|
|9||Dwarf cassowary||Casuarius bennetti||19.7 (43)||34 (75)||105 (3.4)||No|
|10||Lesser rhea||Rhea pennata||19.6 (43)||28.6 (63)||96 (3.2)||No|
|11||Mute swan||Cygnus olor||11.87 (26.2)||23 (51)||100-130 (3.3 - 4.3)||Yes|
|12||Great bustard||Otis tarda||10.6 (23.4)||21 (46)||115 (3.8)||Yes|
|13||King penguin||Aptenodytes patagonicus||13.6 (30)||20 (44)||92 (3)||No|
|14||Kori bustard||Ardeotis kori||11.4 (25.1)||20 (44.1)||150 (5)||Yes|
|15||Trumpeter swan||Cygnus buccinator||11.6 (25.1)||17.2 (38)||138 - 165 (4.5 - 5.4)||Yes|
|16||Wandering albatross||Diomedea exulans||11.9 (24)||16.1 (38)||107 - 135 (3.5 - 4.4)||Yes|
|17||Whooper swan||Cygnus cygnus||11.4 (25)||15.5 (32)||140 - 165 (4.5 - 5.4)||Yes|
|18||Dalmatian Pelican||Pelecanus crispus||11.5 (25)||15 (33.1)||183 (6)||Yes|
|19||Andean condor||Vultur gryphus||11.3 (25)||14.9 (33)||100 - 130 (3.3 - 4.3)||Yes|
The largest living amphibian is the South China giant salamander (Andrias sligoi). Formerly considered conspecific with the Chinese giant salamander (A. davidianus), the maximum size of this nearly human-sized river-dweller is 64 kg (141 lb) and almost 1.83 m (6.0 ft). Before amniotes became the dominant tetrapods, several giant amphibian proto-tetrapods existed and were certainly the dominant animals in their ecosystems. The largest known was the crocodile-like Prionosuchus, which reached a length of 9 m (30 ft).
Main article: List of largest fish
The largest known species of sea sponge is the giant barrel sponge, Xestospongia muta. These massively built sponges can reach 2.4 m (8 ft) in height and can be about the same thickness at the thickest part of the "body". Some of these creatures have been estimated to be over 2,400 years of age. 
The lion's mane jellyfish (Cyanea capillata) is the largest cnidarian species, of the class Scyphozoa. The largest known specimen of this giant, found washed up on the shore of Massachusetts Bay in 1870, had a bell diameter of 2.5 m (8.2 ft), a weight of 150 kg (330 lb). The tentacles of this specimens were as long as 37 m (121 ft) and were projected to have a tentacular spread of about 75 m (246 ft) making it one of the longest extant animals.
Further information: Platyhelminthes
The largest roundworm, Placentonema gigantissima, is a parasite found in the placentas of sperm whales which can reach up to 9 m (30 ft) in length.
The largest of the segmented worms (including earthworms, leeches, and polychaetes) is the African giant earthworm (Microchaetus rappi). Although it averages about 1.36 m (4.5 ft) in length, this huge worm can reach a length of as much as 6.7 m (22 ft) and can weigh over 1.5 kg (3.3 lb). Only the giant Gippsland earthworm, Megascolides australis, and a few giant polychaetes, including the notorious Eunice aphroditois, reach nearly comparable sizes, reaching 4 and 3.6 m (13 and 12 ft), respectively.
The largest species of echinoderm in terms of bulk is probably the starfish species Thromidia gigas, of the class Asteroidea, which reaches a weight of over 6 kg (13 lb), but it might be beaten by some giant sea cucumbers such as Thelenota anax. However, at a maximum span of 63 cm (25 in), Thromidia gigas is quite a bit shorter than some other echinoderms. The longest echinoderm known is the conspicuous sea cucumber Synapta maculata, with a slender body that can extend up to 3 m (9.8 ft). In comparison, the biggest sea star is the brisingid sea star Midgardia xandaros, reaching a span of 1.4 m (4.6 ft), despite being quite slender. Evasterias echinosoma is another giant echinoderm and can measure up to 1 m (3.3 ft) across and weigh 5.1 kg (11 lb).
The largest nemertean is the bootlace worm, Lineus longissimus. A specimen found washed ashore on a beach in St. Andrews, Scotland in 1864 was recorded at a length of 55 m (180 ft).
Both the largest mollusks and the largest of all invertebrates (in terms of mass) are the largest squids. The colossal squid (Mesonychoteuthis hamiltoni) is projected to be the largest invertebrate. Current estimates put its maximum size at 12 to 14 m (39 to 46 ft) long and 750 kg (1,650 lb), based on analysis of smaller specimens. In 2007, authorities in New Zealand announced the capture of the largest known colossal squid specimen. It was initially thought to be 10 m (33 ft) and 450 kg (990 lb). It was later measured at 4.2 m (14 ft) long and 495 kg (1,091 lb) in weight. The mantle was 2.5 m (8.2 ft) long when measured.
The giant squid (Architeuthis dux) was previously thought to be the largest squid, and while it is less massive and has a smaller mantle than the colossal squid, it may exceed the colossal squid in overall length including tentacles. One giant squid specimen that washed ashore in 1878 in Newfoundland reportedly measured 16.8 m (55 ft) in total length (from the tip of the mantle to the end of the long tentacles), head and body length 6.1 m (20 ft), 4.6 m (15 ft) in circumference at the thickest part of mantle, and weighed about 900 kg (2,000 lb). This specimen is still often cited as the largest invertebrate that has ever been examined. However, no animals approaching this size have been scientifically documented and, according to giant squid expert Steve O'Shea, such lengths were likely achieved by greatly stretching the two tentacles like elastic bands.
Solórzano's velvet worm (Peripatus solorzanoi) is the largest velvet worm known. An adult female was recorded to have a body length of 22 cm (approximately 8.7 in).
The largest arthropod known to have existed is the eurypterid (sea scorpion) Jaekelopterus, reaching up to 2.5 m (8.2 ft) in body length, followed by the millipede relative Arthropleura at around 2.1 m (6.9 ft) in length. Among living arthropods, the Japanese spider crab (Macrocheira kaempferi) is the largest in overall size, the record specimen, caught in 1921, had an extended arm span of 3.8 m (12 ft) and weighed about 19 kg (42 lb). The heaviest is the American lobster (Homarus americanus), the largest verified specimen, caught in 1977 off of Nova Scotia weighed 20 kg (44 lb) and its body length was 1.1 m (3.6 ft). The largest land arthropod and the largest land invertebrate is the coconut crab (Birgus latro), up to 40 cm (1.3 ft) long and weighing up to 4 kg (8.8 lb) on average. Its legs may span 1 m (3.3 ft).
Both spiders and scorpions include contenders for the largest arachnids.
The largest crustaceans are crab Tasmanian giant crab (''Pseudocarcinus gigas) 13 kilograms (29 lb) and a carapace width of up to 46 centimetres (18 in). It is the only species in the genus Pseudocarcinus. Males reach more than twice the size of females. It has a white shell with claws that are splashed in red. The females' shells change colour when they are producing eggs. At a length of up to 40 centimetres (16 in), Lysiosquillina maculata is the largest mantis shrimp in the world. L. maculata may be distinguished from its congener L. sulcata by the greater number of teeth on the last segment of its raptorial claw, and by the colouration of the uropodal endopod, the distal half of which is dark in L. maculata but not in L. sulcata. There is a small artisanal fishery for this species. Tasmanian giant freshwater crayfish (Astacopsis gouldi) 5 kilograms (11 lb) in weight and over 80 centimetres (31 in) long have been known in the past, but now, even individuals over 2 kilograms (4.4 lb) are rare. The species is only found in Tasmanian rivers flowing north into the Bass Strait below 400 metres (1,300 ft) above sea level, and is listed as an endangered species on the IUCN Red List.
The four modern horseshoe crabs are of roughly the same sizes, with females measuring up to 60 cm (2.0 ft) in length and 5 kg (11 lb) in weight.
The largest of the sea spiders is the deep-sea species Colossendeis colossea, attaining a leg span of nearly 60 cm (2.0 ft).
Some of these extinct marine arthropods exceeded 60 cm (24 in) in length. A nearly complete specimen of Isotelus rex from Manitoba attained a length over 70 cm (28 in), and an Ogyginus forteyi from Portugal was almost as long. Fragments of trilobites suggest even larger record sizes. An isolated pygidium of Hungioides bohemicus implies that the full animal was 90 cm (35 in) long.
Insects, a class of Arthropoda, are easily the most numerous class of organisms, with over one million identified species, and probably many undescribed species. The heaviest insect is almost certainly a species of beetle, which incidentally is the most species-rich order of organisms. Although heavyweight giant wetas (Deinacrida heteracantha) are known, the elephant beetles of Central and South America, (Megasoma elephas) and (M. actaeon), the Titan beetle (Titanus giganteus) of the neotropical rainforest or the Goliath beetles, (Goliathus goliatus) and (G. regius), of Africa's rainforest are thought to reach a higher weight. The most frequently crowned are the Goliath beetles, the top known size of which is at least 100 g (3.5 oz) and 11.5 cm (4.5 in). The elephant beetles and titan beetle can reach greater lengths than the Goliath, at up to 13.1 and 15.2 cm (5.2 and 6.0 in), respectively, but this is in part thanks to their rather large horns. The Goliath beetle's wingspan can range up to 25 cm (9.8 in).
Some moths and butterflies have much larger areas than the heaviest beetles, but weigh a fraction as much.
The longest insects are the stick insects, see below.
Representatives of the extinct dragonfly-like order Protodonata such as the Carboniferous Meganeura monyi of what is now France and the Permian Meganeuropsis permiana of what is now North America are the largest insect species yet known to have existed. These creatures had a wingspan of some 75 cm (30 in) and a mass of over 1 pound (450 g), making them about the size of a crow.
The largest living fungus may be a honey fungus of the species Armillaria ostoyae. A mushroom of this type in the Malheur National Forest in the Blue Mountains of eastern Oregon, U.S. was found to be the largest fungal colony in the world, spanning 8.9 km2 (2,200 acres) of area. This organism is estimated to be 2,400 years old. The fungus was written about in the April 2003 issue of the Canadian Journal of Forest Research. While an accurate estimate has not been made, the total weight of the colony may be as much as 605 tons[vague]. If this colony is considered a single organism, then it is the largest known organism in the world by area, and rivals the aspen grove "Pando" as the known organism with the highest living biomass. It is not known, however, whether it is a single organism with all parts of the mycelium connected.
A spatial genetic analysis estimated that a specimen of Armillaria ostoyae growing over 91 acres (37 ha) in northern Michigan, United States weighs 440 tons (4 x 105 kg). Approximations of the land area of the Oregon "humongous fungus" are 3.5 square miles (9.1 km2) (2,240 acres (910 ha), possibly weighing as much as 7,500 tons as the world's most massive living organism.
In Armillaria ostoyae, each individual mushroom (the fruiting body, similar to a flower on a plant) has only a 5 cm (2.0 in) stipe, and a pileus up to 12.5 cm (4.9 in) across. There are many other fungi which produce a larger individual size mushroom. The largest known fruiting body of a fungus is a specimen of Phellinus ellipsoideus (formerly Fomitiporia ellipsoidea) found on Hainan Island. The fruiting body masses up to 500 kg (1,100 lb).
Until P. ellipsoideus replaced it, the largest individual fruit body came from Rigidoporus ulmarius. R. ulmarius can grow up to 284 kg (626 lb), 1.66 m (5.4 ft) tall, 1.46 m (4.8 ft) across, and has a circumference of up to 4.9 m (16 ft).
(Note: the group Protista is not used in current taxonomy.)
The largest known species of bacterium is Thiomargarita namibiensis, which grows to 0.75 mm (0.030 in) in diameter, making it visible to the naked eye and a thousand times the size of more typical bacteria.
The largest virus on record is the Pithovirus sibericum with the length of 1.5 micrometres, comparable to the typical size of a bacterium and large enough to be seen in light microscopes. It was discovered in March 2014 in an ice core sample collected from a permafrost in Siberia. Prior to this discovery, the largest virus was the peculiar virus genus Pandoravirus, which have a size of approximately 1 micrometer and whose genome contains 1,900,000 to 2,500,000 base pairs of DNA.
Both these viruses infect amoebas specifically.
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