The largest extant animal, as well as the largest animal to ever exist, is the blue whale. The maximum recorded weight was 190 tonnes (209 short tons) 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 that this individual could have a mass of 250 tonnes or more. The longest non-colonial animal is the lion's mane jellyfish (120 ft, 36.6 m). While controversial, estimates for the weight of the sauropod Bruhathkayosaurus suggest it was around 110–170 tons, with the highest estimate being 240 tons, if scaled with Patagotitan, although actual fossil remains no longer exist, and that estimation is based on described dimensions in 1987. Similarly, the extinct whale Perucetus was initially estimated in 2023 to have a mass of 85 to 340 t (94–375 short tons; 84–335 long tons). However, more recent studies suggest this whale was much smaller than previous estimates, with a 2024 study putting its weight at 60 to 113 tonnes, while a 2025 study further downsized its weight to 35 to 40 tonnes. In April 2024, Ichthyotitan severnensis was established as a valid shastasaurid taxon and is considered both the largest marine reptile ever discovered and the largest macropredator ever discovered. The Lilstock specimen was estimated to be around 26 metres (85 ft) whilst the Aust specimen was an even more impressive 30 to 35 metres (98 to 115 ft) in length (however, the Aust specimen or 'Aust Colossus' may not belong to Ichthyotitan). While no weight estimates have been made as of yet, Ichthyotitan would have easily rivalled or surpassed the blue whale. The upper estimates of weight for these prehistoric animals would have easily rivaled or exceeded the largest rorquals and sauropods. However, an as-yet undescribed shastasaurid, informally referred to as 'Aust Colossus', may have exceeded Ichthyotitan in size, potentially making it the largest known marine reptile. It has been estimated at approximately 30 metres in length, which would surpass the blue whale; however, the authors note that this estimate is highly speculative. The African bush elephant (Loxodonta africana) is the largest living land animal. A native of various open habitats in sub-Saharan Africa, males weigh about 6 tonnes (13,000 lb) on average. 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 10.4 to 12.25 tonnes.
Heaviest living animals
The heaviest living animals are all whales. There are considerable obstacles to overcome in obtaining accurate weights for them, however, as no scale can accommodate the whole body of a large whale. Whaling factories are usually enlisted to help accomplish the task, but it still remains difficult, and most weighings have been done by parts of flensed whales, leaving much room for error. Mathematical formulas have also been devised to estimate the average weight of various whale species based on body length, but this method is equally prone to inaccuracy.
Heaviest terrestrial animals The heaviest land animals 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.
Vertebrates
Mammals (Mammalia)
The blue whale is the largest animal, and therefore the largest mammal, of all time, with the longest known specimen being 33 m (108.3 ft) long and the heaviest weighted specimen being 190 tonnes. The extinct whale species Perucetus colossus was shorter than the blue whale, at 17.0–20.1 meters (55.8–65.9 ft) but it is estimated to have rivaled or surpassed it in weight, at 85–340 tonnes. At the highest estimates, this would make Perucetus the heaviest known animal in history, although more recent estimates put it at a more moderate 60 to 113 tonnesor 35 to 40 tonnes 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 the extinct elephant Palaeoloxodon namadicus may have been the largest land mammal ever, based on a fragmentary femur estimated to belong to an individual with maximum weight of 22 tonnes. This author also suggested that the extinct mastodon "Mammut" borsoni may have rivalled P. namadicus in size.. However, these estimates remain debated due to the fragmentary nature of the fossil material and the uncertainties involved in scaling from limited remains. In 2022, a study proposed that Dzungariotherium may be the largest paracerathere, surpassing even Paraceratherium thus it represents another contender for the largest terrestrial mammal ever, with estimates of approximately 20.6 tonnes.
Stem-mammals (Synapsida)
The Late Triassic 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) in length, 2.6 m (8.5 ft) in height and 9 t (20,000 lb) in weight. 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 at 5–6 m (16–20 ft) and 500–600 kg (1,100–1,300 lb).
Caseasaurs (Caseasauria) The herbivorous Alierasaurus was the largest caseid and the largest amniote to have lived at the time, with an estimated length around 6–7 m (20–23 ft). Another huge caseasaur is Cotylorhynchus hancocki, with an estimated length and weight of at least 6 m (20 ft) and more than 500 kg (1,100 lb).
Sphenacodontids (Sphenacodontidae)
The biggest carnivorous synapsid of Early Permian was Dimetrodon, which could reach 4.6 m (15 ft) and 250 kg (550 lb). The largest members of the genus Dimetrodon were also the world's first fully terrestrial apex predators.
Tappenosaurids (Tappenosauridae)
The Middle Permian Tappenosaurus was estimated at 5.5 m (18 ft) in length which is comparable in size with the largest dinocephalians.
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