Largest and heaviest animals
The largest animal currently alive is the blue whale. The maximum recorded weight was 190 tonnes for a specimen measuring , whereas longer ones, up to , have been recorded but not weighed. It is estimated, this individual could have a mass of 250 tonnes. The longest non-colonial animal is the lion's mane jellyfish (36.6m / 120 ft). In 2023, paleontologists estimated that the extinct whale Perucetus, discovered in Peru, may have outweighed the blue whale, with a mass of 85-340 t (84-335 long tons; 94-375 short tonnes.) 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. The upper estimates of weight for these two prehistoric animals would have easily rivaled or exceeded the blue whale. 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  on average. The largest elephant ever recorded was shot in Angola in 1974. It was a male measuring  from trunk to tail and  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 . This male had a computed weight of 10.4 tonnes. Heaviest living animals 
The heaviest living animals are all whales. Since no scale can accommodate the whole body of a large whale, most have been weighed by parts. 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 two separate species. Vertebrates

Mammals (Mammalia)

The blue whale is the largest mammal of all time, with the largest known specimen being  long and the largest 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. 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  tall, measured over  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. 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  in length,  in height and  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  and . Caseasaurs (Caseasauria)
The herbivorous Alierasaurus was the largest caseid and the largest amniote to have lived at the time, with an estimated length around . Another huge caseasaur is Cotylorhynchus hancocki, with an estimated length and weight of at least  and more than . Sphenacodontids (Sphenacodontidae)
The biggest carnivorous synapsid of Early Permian was Dimetrodon, which could reach  and . 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  in length which is comparable in size with the largest dinocephalians. Therapsids (Therapsida)
The plant-eating dicynodont Lisowicia bojani is the largest-known of all non-mammalian synapsids, at  and . The largest carnivorous therapsid was the aforementioned Anteosaurus from what is now South Africa during Middle Permian epoch. It reached  long, and about  in weight. Reptiles (Reptilia)

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  long. The largest confirmed saltwater crocodile on record was  long, and weighed about . Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than . Also, a living specimen estimated at  and  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  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  in rare cases and weighing up to approximately . Largest living reptiles
The following is a list of the largest 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. Dinosaurs (Dinosauria)

Dinosaurs are now extinct, except for birds, which are theropods. Sauropods (Sauropoda)
The largest dinosaurs, and the largest animals to ever live on land, were the plant-eating, long-necked Sauropoda. The tallest and heaviest sauropod known from a complete skeleton is a specimen of an immature Giraffatitan discovered in Tanzania between 1907 and 1912, now mounted in the Museum für Naturkunde of Berlin. It is  tall and weighed 23.3–39.5 tonnes. The longest is a  long specimen of Diplodocus discovered in Wyoming, and mounted in Pittsburgh's Carnegie Natural History Museum in 1907. A Patagotitan specimen found in Argentina in 2014 is estimated to have been  long and  tall, with a weight of 69–77 tonnes. There were larger sauropods, but they are known only from a few bones. The current record-holders include Argentinosaurus, which may have weighed 100 tonnes; Supersaurus which might have reached  in length and Sauroposeidon which might have been  tall. Some abnormal specimens such as specimen BYU 9024 of the Barosaurus genus could reach an astounding 45-48 meters long, with mass varying from the 'modest' 60-66 tons to the more immense 92-120 tons. Two other such sauropods include Bruhathkayosaurus and Maraapunisaurus. Both are known only from fragments that are no longer exist. Bruhathkayosaurus might have been between  in length and 175–220 tonnes in weight according to some estimates, with recent estimates being place between 110-170 tons. Maraapunisaurus might have been approximately 35–40 m long and 80–120 tonnes or more. Each of these two 'super-sauropods' would have easily rivalled the largest blue whale in size. Theropods (Theropoda)
The largest theropod known from a nearly complete skeleton is the most complete Tyrannosaurus rex specimen, nicknamed "Sue", which was discovered in South Dakota in 1990 and now mounted in the Field Museum of Chicago at a total length of . Body mass estimates have reached over 9,500 kg, though other figures, such as Hartman's 2013 estimate of 8,400 kg, have been lower. Another giant theropod is Spinosaurus aegyptiacus from the mid-Cretaceous of North Africa. Size estimates have been fluctuating far more over the years, with length estimates ranging from 12.6 to 18 m and mass estimates from 7 to 20.9 t. Recent findings favor a length exceeding 15 m  and a body mass of 7.5 tons. Other contenders known from partial skeletons include Giganotosaurus carolinii (est. 12.2–13.2 m and 6-13.8 tonnes) and Carcharodontosaurus saharicus (est. 12-13.3 m and 6.2-15.1 tonnes). The largest extant theropod is the common ostrich (see birds, below). Armored dinosaurs (Thyreophora)
The largest thyreophorans were Ankylosaurus and Stegosaurus, from the Late Cretaceous and Late Jurassic periods (respectively) of what is now North America, both measuring up to  in length and estimated to weigh up to 6 tonnes. Ornithopods (Ornithopoda)
The largest ornithopods were the hadrosaurids Shantungosaurus, a late Cretaceous dinosaur found in the Shandong Peninsula of China, and Magnapaulia from the late Cretaceous of North America. Both species are known from fragmentary remains but are estimated to have reached over  in length and were likely the heaviest non-sauropod dinosaurs, estimated at over 23 tonnes. Ceratopsians (Ceratopsia)
The largest ceratopsians were Triceratops and its ancestor Eotriceratops from the late Cretaceous of North America. Both estimated to have reached about  in length and weighed 12 tonnes. Birds (Aves)

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  and weigh over . A mass of  has been cited for the common ostrich but no wild ostriches of this weight have been verified. Eggs laid by the ostrich can weigh  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  in height and , while Vorombe could reach a similar height and a mass of . 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  and a height of about . 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  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 , a length of up to , a height on the ground of up to  and a body weight of at least . Pelagornis sandersi is thought to have had an even larger wingspan of about , but is only about , half the mass of the former. Heaviest living bird species
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. Amphibians (Amphibia)

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  and almost . 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 . Frogs (Anura)

The largest member of the largest order of amphibians is the African goliath frog (Conraua goliath). The maximum size this species is verified to attain is a weight of  and a snout-to-vent length of . The largest of the toads, the cane toad (Rhinella marina), is also the second largest member of the frog order. This infamous, often invasive species can grow to maximum mass of  and measure a maximum of  from snout-to-vent. Rivaling the previous two species, the African bullfrog (Pyxicephalus adspersus) can range up to a weight of  and  from snout to vent. Another large frog is the largest frog in North America, the American bullfrog, which can reach weights of up to  and snout-to-vent-length (SVL) of . However, the toad Beelzebufo ampinga, found in fossil from the Cretaceous era in what is now Madagascar, was estimated to grow to  long and weigh up to , making it the largest frog ever known. But in more recent studies, animals of this species have been estimated to have grown to at least  (snout-vent length), which is around the size a modern African bullfrog can reach. The largest tree frog is the Australasian white-lipped tree frog (Litoria infrafrenata), the females of which can reach a length of  from snout to vent and can weigh up to . The family Leptodactylidae, one of the most diverse anuran families, also has some very large members. The largest is the Surinam horned frog (Ceratophrys cornuta), which can reach  in length from snout to vent and weigh up to . While not quite as large as Ceratophrys cornuta, Leptodactylus pentadactylus is often heavier; it can reach  long and weigh . The largest dendrobatid is the Colombian golden poison frog (Phyllobates terribilis), which can attain a length of  and nearly . Most frogs are classified under the suborder Neobatrachia, although nearly 200 species are part of the suborder Mesobatrachia, or ancient frogs. The largest of these are the little-known Brachytarsophrys or Karin Hills frogs, of South Asia, which can grow to a maximum snout-to-vent length of  and a maximum weight of . Caecilians (Gymnophiona)
The largest of the worm-like caecilians is the Colombian Thompson's caecilian (Caecilia thompsoni), which reaches a length of , a width of about  and can weigh up to about . Salamanders (Urodela)
Besides the previously mentioned Chinese and South China giant salamanders, the closely related Japanese giant salamander (Andrias japonicus) is also sometimes cited as the largest living amphibian, but salamanders of a greater size than  and  have never been verified for this species. Another giant of the amphibian world is the North American hellbender (Cryptobranchus alleganiensis), which can measure up to . The recently described reticulated siren of the southeastern United States rivals the hellbender in size, although it is more lean in build. The largest of the newts is the Iberian ribbed newt (Pleurodeles waltl), which can grow up to  in length. Fish

Invertebrate chordates

Tunicates (Tunicata)

The largest tunicates are Synoicum pulmonaria, found at depths of , 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 . Entergonas (Enterogona)
The largest entergonas Synoicum pulmonaria it is usually found at depths between about  and can grow to over a metre (yard) in length. 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 . Pleurogonas (Pleurogona)
The largest pleurogonas: Pyura pachydermatina . In colour it is off-white or a garish shade of reddish-purple. The stalk is two thirds to three quarters the length of the whole animal which helps distinguish it from certain invasive tunicates not native to New Zealand such as Styela clava and Pyura stolonifera. It is one of the largest species of tunicates and can grow to over a metre (yard) in length. Aspiraculates (Aspiraculata)
The largest aspiraculates: Oligotrema large and surrounded by six large lobes; the cloacal syphon is small. They live exclusively in deep water and range in size from less than one inch (2 cm) to 2.4 inches (6 cm). Thaliacea

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  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. Doliolida (Doliolida)
The largest doliolida: Doliolida  The doliolid body is small, typically 1–2 cm long, and barrel-shaped; it features two wide siphons, one at the front and the other at the back end, and eight or nine circular muscle strands reminiscent of barrel bands. Like all tunicates, they are filter feeders. They are free-floating; the same forced flow of water through their bodies with which they gather plankton is used for propulsion - not unlike a tiny ramjet engine. Doliolids are capable of quick movement. They have a complicated lifecycle consisting of sexual and asexual generations. They are nearly exclusively tropical animals, although a few species are found as far north as northern California. Salps (Salpida)
The largest salps: Cyclosalpa bakeri 15cm (6ins) long. There are openings at the anterior and posterior ends of the cylinder which can be opened or closed as needed. The bodies have seven transverse bands of muscle interspersed by white, translucent patches. A stolon grows from near the endostyle (an elongated glandular structure producing mucus for trapping food particles). The stolon is a ribbon-like organ on which a batch of aggregate forms of the animal are produced by budding. The aggregate is the second, colonial form of the salp and is also gelatinous, transparent and flabby. It takes the shape of a radial whorl of individuals up to about 20cm (4in) in diameter. It is formed of approximately 12 zooids linked side by side in a shape that resembles a crown. are largest thetyses: Thetys vagina Individuals can reach up to  long. Larvaceans (Larvacea)
The largest larvaceans: Appendicularia  in body length (excluding the tail). Cephalochordates (Leptocardii)

The largest lancelet is the European lancelet (Branchiostoma lanceolatum) "primitive fish". It can grow up to 6 cm (2.5 in) long. Invertebrate non-chordates

Echinoderms (Echinodermata)

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 , but it might be beaten by some giant sea cucumbers such as Thelenota anax. However, at a maximum span of , 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 . In comparison, the biggest sea star is the brisingid sea star Midgardia xandaros, reaching a span of , despite being quite slender. Evasterias echinosoma is another giant echinoderm and can measure up to  across and weigh . Crinoids (Crinoidea)
The largest species of crinoid is the unstalked feather-star Heliometra glacialis, reaching a total width of  and an individual arm length of . A width of  was claimed for one unstalked feather-star but is not confirmed. The genus Metacrinus has a stalk span of  but, due to its bulk and multiple arms, it is heavier than Heliometra. In the past, crinoids grew much larger, and stalk lengths up to  have been found in the fossil record. Sea urchins and allies (Echinoidea)
The largest sea urchin is the species Sperosoma giganteum from the deep northwest Pacific Ocean, which can reach a shell width of about . Another deep sea species Hygrosoma hoplacantha is only slightly smaller. The largest species found along the North America coast is the Pacific red sea urchin (Mesocentrotus franciscanus) where the shell can reach . If the spines enter into count, the biggest species may be a Diadematidae like Diadema setosum, with a test up to  only, but its spines can reach up to  in length. Sea cucumbers (Holothuroidea)
The bulkiest species of sea cucumber are Stichopus variegatus and Thelenota anax, weighing several pounds, being about  in diameter, and reaching a length of  when fully extended. Synapta maculata can reach an extended length of , but is extremely slender (3-5cm) and weigh much less than Stichopodids. Brittle stars (Ophiuroidea)
The largest known specimen of brittle star is the basket star Astrotoma agassizii. This species can grow to have a span of . Sometimes, Gorgonocephalus stimpsoni is considered the largest but the maximum this species is can measure  and a disk diameter of about . Outside from euryalids, the biggest ophiurid brittle star may be Ophiopsammus maculata (6–7 inches). Sea stars (Asteroidea)
The heaviest sea star is Thromidia gigas from the Indo-Pacific, which can surpass  in weight, but only has a diameter of about . Despite its relatively small disk and weight, the long slender arms of Midgardia xandaros from the Gulf of California makes it the sea star with the largest diameter at about . Mithrodia clavigera may also become wider than  in some cases, with stout arms. Flatworms (Platyhelminthes)

Monogenean flatworms (Monogenea)
The largest known members of this group of very small parasites are among the genus of capsalids, Listrocephalos, reaching a length of . Flukes (Trematoda)
The largest known species of fluke is Fasciolopsis buski, which most often attacks humans and livestock. One of these flukes can be up to  long and  thick. Tapeworms (Cestoda)
The largest known species of tapeworm is the whale tapeworm, Polygonoporus giganticus, which can grow to over . Segmented worms (Annelida)
The largest of the segmented worms (including earthworms, leeches, and polychaetes) is the African giant earthworm (Microchaetus rappi). Although it averages about  in length, this huge worm can reach a length of as much as  and can weigh over . Only the giant Gippsland earthworm, Megascolides australis, and a few giant polychaetes, including the notorious Eunice aphroditois, reach nearly comparable sizes, reaching , respectively. Ribbon worms (Nemertea)
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 . Mollusks (Mollusca)

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  long and , 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  and . It was later measured at  long and  in weight. The mantle was  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  in total length (from the tip of the mantle to the end of the long tentacles), head and body length ,  in circumference at the thickest part of mantle, and weighed about . 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. Aplacophorans (Aplacophora)
The largest known of these worm-like, shell-less mollusks are represented in the genus Epimenia, which can reach  long. Most aplacophorans are less than  long. Chitons (Polyplacophora)
The largest of the chitons is the gumboot chiton, Cryptochiton stelleri, which can reach a length of  and weigh over . Bivalves (Bivalvia)
The largest of the bivalve mollusks is the giant clam, Tridacna gigas. Although even larger sizes have been reported for this passive animal, the top verified size was for a specimen from the Great Barrier Reef. This creature weighed , had an axial length of  and depth of . The largest bivalve ever was Platyceramus platinus, a Cretaceous giant that reached an axial length of up to 3 m (nearly 10 ft). Gastropods (Gastropoda)
The "largest" of this most diverse and successful mollusk class of slugs and snails can be defined in various ways. The living gastropod species that has the largest (longest) shell is Syrinx aruanus with a maximum shell length of , a weight of  and a width of . Another giant species is Melo amphora, which in a 1974 specimen from Western Australia, measured  long, had a maximum girth of  and weighed . The largest shell-less gastropod is the giant black sea hare (Aplysia vaccaria) at  in length and almost  in weight. The largest of the land snails is the giant African snail (Achatina achatina) at up to  and  long. Cephalopods (Cephalopoda)
(See Cephalopod size.) While generally much smaller than the giant Architeuthis and Mesonychoteuthis, the largest of the octopuses, the giant Pacific octopus (Enteroctopus dofleini), can grow to be very large. The largest confirmed weight of a giant octopus is , with a  arm span (with the tentacles fully extended) and a head-to-tentacle-tip length of . Specimens have been reported up to  but are unverified. A weight of 10 - 50kg is a much more common size. Roundworms (Nematoda)
The largest roundworm, Placentonema gigantissima, is a parasite found in the placentas of sperm whales which can reach up to  in length. Velvet worms (Onychophora)
The largest velvet worm known is Solórzano's velvet worm (Peripatus solorzanoi). An adult female was recorded to have a body length of 22 cm (approximately 8.7 in). Arthropods (Arthropoda)

The largest arthropod known to have existed is the eurypterid (sea scorpion) Jaekelopterus, reaching up to  in body length, followed by the millipede relative Arthropleura at around  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  and weighed about . The heaviest is the American lobster (Homarus americanus), the largest verified specimen, caught in 1977 off of Nova Scotia weighed  and its body length was . The largest land arthropod and the largest land invertebrate is the coconut crab (Birgus latro), up to  long and weighing up to  on average. Its legs may span . Arachnids (Arachnida)
Both spiders and scorpions include contenders for the largest arachnids. Spiders (Araneae)
The largest species of arachnid by length is probably the giant huntsman spider (Heteropoda maxima) of Laos, which in 2008 replaced the Goliath birdeater (Theraphosa blondi) of northern South America as the largest known spider by leg-span. However the most massive arachnids, of comparable dimensions and possibly even greater mass, are the Chaco golden knee (Grammostola pulchripes), and the Brazilian salmon pink (Lasiodora parahybana). The huntsman spider may span up to  across the legs, while in the New World tarantulas like Theraphosa can range up to . In Grammostola, Theraphosa and Lasiodora, the weight is projected to be up to at least  and body length is up to . Scorpions (Scorpiones)
The largest of the scorpions is the species Heterometrus swammerdami of the Indian subcontinent, which have a maximum length of  and weigh around . Another extremely large scorpion is the African emperor scorpion (Pandinus imperator), which can weigh  but is not known to exceed a length of . However, they were dwarfed by Pulmonoscorpius kirktonensis, a giant extinct species of scorpion from Scotland, at an estimated length of , and the aquatic Brontoscorpio, at up to  even through only known from finger. Pseudoscorpions (Pseudoscorpiones)
 The largest pseudoscorpion is Garypus titanius, from Ascension island, which can be  long. Crustaceans (Crustacea)
The largest crustacean is the Tasmanian giant crab (Pseudocarcinus gigas), with a weight of  and a carapace width of up to . It is the only species in the genus Pseudocarcinus. Males reach more than twice the size of females. At a length of up to , Lysiosquillina maculata is the largest mantis shrimp in the world. Tasmanian giant freshwater crayfish (Astacopsis gouldi)  in weight and over  long have been known in the past, but now, even individuals over  are rare. The species is only found in Tasmanian rivers flowing north into the Bass Strait below  above sea level, and is listed as an endangered species on the IUCN Red List. Branchiopods (Branchiopoda)
The largest of these primarily freshwater crustaceans is probably Branchinecta gigas, which can reach a length . Barnacles and allies (Maxillopoda)
The largest species is Pennella balaenopterae, a copepod and ectoparasite specialising in parasitising marine mammals. The maximum size attained is 32 cm (about 13 in). The largest of the barnacles is the giant acorn barnacle, Balanus nubilis, reaching  in diameter and  high. Ostracods (Ostracoda)
The largest living representative of these small and little-known but numerous crustaceans is the species Gigantocypris australis females of which reaching a maximum length of . Amphipods, isopods, and allies (Peracarida)
The largest species is the giant isopod (Bathynomus pergiganteus), which can reach a length of 45 cm (18 inches) and a weight of 1.7 kg (3.7 lb). Remipedes (Remipedia)
The largest of these cave-dwelling crustaceans is the species Godzillius robustus, at up to . Horseshoe crabs (Xiphosura)
The four modern horseshoe crabs are of roughly the same sizes, with females measuring up to  in length and  in weight. Sea spiders (Pycnogonida)
The largest of the sea spiders is the deep-sea species Colossendeis colossea, attaining a leg span of nearly . Trilobites (Trilobita)
Some of these extinct marine arthropods exceeded  in length. A nearly complete specimen of Isotelus rex from Manitoba attained a length over , 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  long. Myriapods (Myriapoda)
Centipedes (Chilopoda)

The biggest of the centipedes is Scolopendra gigantea of the neotropics, reaching a length of . Millipedes (Diplopoda)
Two species of millipede both reach a very large size: Archispirostreptus gigas of East Africa and Scaphistostreptus seychellarum, endemic to the Seychelles islands. Both of these species can slightly exceed a length of  and measure over  in diameter. The largest ever known was the Arthropleura, a gigantic prehistoric specimen that reached nearly . Symphylans (Symphyla)
The largest known symphylan is Hanseniella magna, originating in Tasmanian caves, which can reach lengths from  up to . Insects (Insecta)

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  and . The elephant beetles and titan beetle can reach greater lengths than the Goliath, at up to , respectively, but this is in part thanks to their rather large horns. The Goliath beetle's wingspan can range up to . 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 Meganisoptera, 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 known to have existed. These creatures had a wingspan of some  and a mass of over , making them about the size of a crow. Cockroaches and termites (Blattodea)

The largest cockroach by body mass is the Australian giant burrowing cockroach (Macropanesthia rhinoceros), also known as the rhinoceros cockroach. This species can attain a length of  and a weight of . It does not have wings. The Brazilian giant cockroach (Blaberus giganteus) of the neotropics reaches greater sizes of up to 10 cm in length and 15 cm in wingspan, although it is not as massive and heavy as the burrowing species. The termites, traditionally classified in their own order (Isoptera), have recently been re-considered to belong in Blattodea. The largest of the termites is the African species Macrotermes bellicosus. The queen of this species can attain a length of  and breadth of  across the abdomen; other adults, on the other hand, are about a third of the size. Beetles (Coleoptera)
The beetles are the largest order of organisms on earth, with about 400,000 species so far identified. The most massive species are the Goliathus, Megasoma and Titanus beetles already mentioned. Another fairly large species is the Hercules beetle (Dynastes hercules) of the neotropic rainforest with a maximum overall length of at least  including the extremely long pronotal horn. The weight in this species does not exceed . The longest overall beetle is a species of longhorn beetle, Batocera wallacei, from New Guinea, which can attain a length of , about  of which is comprised by the long antennae. Earwigs (Dermaptera)
Since 1798, the largest of the earwigs has been the Saint Helena giant earwig (Labidura herculeana), endemic to the island of its name, measuring up to  in length. As of 2014, with the declaring of the organism extinct by the IUCN, this may no longer be the case, although some believe a small number individuals are still extant. True flies (Diptera)

The largest species of this order, which includes the common housefly, is the neotropical species Gauromydas heros, which can reach a length of  and a wingspan of . Species of crane fly, the largest of which is Holorusia brobdignagius, can attain a length of  but are extremely slender and much lighter in weight than Gauromydas. Mayflies (Ephemeroptera)
The largest mayflies are members of the genus Proboscidoplocia from Madagascar. These insects can reach a length of . True bugs (Hemiptera)

The largest species of this diverse order is usually listed as the giant water bug in the genus Lethocerus, with L. maximus from the Neotropics being the absolutely largest. They can surpass  in length, with some suggesting that the maximum size is . It is more slender and less heavy than most other insects of this size (principally the huge beetles). The largest cicada is Megapomponia imperatoria, which has a head-body length of about  and a wingspan of . The cicadas of the genus Tacua can also grow to comparably large sizes. The largest type of aphid is the giant oak aphid (Stomaphis quercus), which can reach an overall length of . The biggest species of leafhopper is Ledromorpha planirostris, which can reach a length of . Ants and allies (Hymenoptera)
The largest of the ants, and the heaviest species of the order, are the females of the African Dorylus helvolus, reaching a length of  and a weight of . The ant that averages the largest for the mean size within the whole colony is a ponerine ant, Dinoponera gigantea, from South America, averaging up to  from the mandibles to the end of abdomen. Workers of the bulldog ant (Myrmecia brevinoda) of Australia are up to  in total length, although much of this is from their extremely large mandibles. The largest of the bee species, also in the order Hymenoptera, is Megachile pluto of Indonesia, the females of which can be  long, with a  wingspan. Nearly as large, the carpenter bees can range up to . The largest wasp is probably the so-called tarantula hawk species Pepsis pulszkyi of South America, at up to  long and  wingspan, although many other Pepsis approach a similar size. The giant scarab-hunting wasp Megascolia procer may rival the largest tarantula hawks in weight and wingspan, though its body is not as long. Moths and allies (Lepidoptera)
The Hercules moth (Coscinocera hercules), in the family Saturniidae, is endemic to New Guinea and northern Australia, and its wings have the largest documented surface area (300 square centimeters) of any living insect, and a maximum wingspan which is confirmed to  while unconfirmed specimens have spanned up to . The largest species overall is often claimed to be either the Queen Alexandra's birdwing (Ornithoptera alexandrae), a butterfly from Papua New Guinea, or the Atlas moth (Attacus atlas), a moth from Southeast Asia. Both of these species can reach a length of , a wingspan of  and a weight of . One Atlas moth allegedly had a wingspan of  but this measurement was not verified. The larvae in the previous species can weigh up to , respectively. However, there are no reported measurements of surface area that would exceed the Hercules moth, and the white witch (Thysania agrippina) of Central and South America, has the largest recorded wingspan of the order, and indeed of any living insect, though the white witch is exceeded in surface area by the Hercules moth. The verified record-sized Thysania spanned  across the wings, although specimens have been reported to . The heaviest mature moths have been cited in the giant carpenter moth (Xyleutes boisduvali) of Australia, which has weighed up to  although the species does not surpass  in wingspan. Mantises (Mantodea)
The largest species of this order is Toxodera denticulata from Java, which has been measured up to  in overall length. However, an undescribed species from the Cameroon jungle is allegedly much larger than any other mantis and may rival the larger stick insects for the longest living insect. Among widespread mantis species, the largest is the Chinese mantis (Tenodera aridifolia). The females of this species can attain a length of up to . Scorpionflies (Mecoptera)
The largest scorpionfly, the common scorpionfly (Panorpa communis), can reach a body length of about . Alderflies and allies (Megaloptera)
This relatively small insect order includes some rather large species, many of which are noticeable for their elongated, imposing mandibles. The dobsonflies reach the greatest sizes of the order and can range up to  in length. Net-winged insects (Neuroptera)

These flying insects reach their largest size in Palparellus voeltzkowi, which can have a wingspan over . The largest lacewing is the "blue eyes lacewing" (Nymphes myrmeleonides) of Australia, which can measure up to  in length and span  across the wings. Some forms of this ancient order could grow extremely large during the Jurassic period and may have ranked among the largest insects ever. Found in the Early Cretaceous sedimentary rocks, Makarkinia adamsi had wings nearly  in length. Dragonflies (Odonata)
The largest species of dragonfly is Megaloprepus caerulatus of the neotropics, attaining a size of as much as  across the wings and a body length of over . Spanning up to  and measuring up to  long, Tetracanthagyna plagiata of Southeast Asia is bulkier and heavier than Megaloprepus at up to . Grasshoppers and allies (Orthoptera)

The largest of this widespread, varied complex of insects are the giant wetas of New Zealand, which is now split among 12 species. The largest of these is the Little Barrier Island giant weta (Deinacrida heteracantha), the largest specimen was weighed at , one of the largest insects weights ever known. These heavyweight insects can be over  long. The largest grasshopper species is often considered to be the Australian giant grasshopper (Valanga irregularis), which ranges up to  in length. The American eastern lubber grasshopper (Romalea guttata) can allegedly range up to  in length. However, the greatest grasshopper sizes known, to , have been cited in the South American giant grasshopper (Tropidacris violaceus). The longest members of this order (although much lighter than the giant wetas) is the katydid Macrolyristes corporalis of Southeast Asia which can range up to  with its long legs extended and can have a wingspan of . Stick insects (Phasmatodea)
The longest known stick insects are also the longest known insects, notably species in the tribe Pharnaciini, but they are generally relatively lightweight because of their slender shape. The longest is an unnamed species of Phryganistria discovered in China in 2016, where a specimen held at the Insect Museum of West China in Chengdu has a total length of . The second-longest species is the Australian Ctenomorpha gargantua, females of which have been measured at over  in total length. Other very large species, formerly believed to be longest but now considered third longest is Sadyattes chani; a specimen held in the Natural History Museum in London has a total length of . These measurements are, however, with the front legs fully extended; it has a body length measuring . Another very large species is Phobaeticus kirbyi where the total length (including extended legs) is up to  and the body alone up to . Another of the longest insect in terms of total length is Phobaeticus serratipes of Malaysia and Singapore, measuring up to . Another extremely long stick insect is Pharnacia maxima, which measured  with its legs extended. The spiny stick insect (Heteropteryx dilatata) of Malaysia does not reach the extreme lengths of its cousins, the body reaching up to  long, but it is much bulkier. The largest Heteropteryx weighed about  and was  wide across the thickest part of the body. Lice (Phthiraptera)
These insects, which live parasitically on other animals, are as a rule quite small. The largest known species is the hog louse, Haematopinus suis, a sucking louse that lives on large livestock like pigs and cattle. It can range up to  in length. Stoneflies (Plecoptera)
The largest species of stonefly is Pteronarcys californica of western North America, a species favored by fishermen as lures. This species can attain a length of  and a wingspan of over . Booklice (Psocoptera)
The largest of this order of very small insects are the barklice of the genus Psocus, the top size of which is about 1 cm. Fleas (Siphonaptera)
The largest species of flea is Hystrichopsylla schefferi. This parasite is known exclusively from the fur of the mountain beaver (Aplodontia rufa) and can reach a length of . Silverfishes and allies (Thysanura)
These strange-looking insects, known to feed on human household objects, can range up to  in length. A 350 million year old form was known to grow quite large, at up to . Thrips (Thysanoptera)
Members of the genus Phasmothrips are the largest kinds of thrips. The maximum size these species attain is approximately  in length. Caddisflies (Trichoptera)
The largest of the small, moth-like caddisflies is Eubasilissa maclachlani. This species can range up to  across the wings. Angel insects (Zoraptera)
The largest angel insect species, Hubbard's angel insect (Zorotypus hubbardi), grows up to  in length. Cnidarians (Cnidaria)

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 , a weight of . The tentacles of this specimens were as long as  and were projected to have a tentacular spread of about  making it one of the longest extant animals. Corals and sea anemones (Anthozoa)
The largest individual species are the sea-anemones of the genus Discoma, which can attain a mouth disc diameter of . Longer, but much less massive overall, are the anemones of the genus Ceriantharia, at up to  tall. Communities of coral can be truly massive, a single colony of the genus Porites can be over , but the actual individual organisms are quite small. Hydrozoans (Hydrozoa)
The colonial siphonophore Praya dubia can attain lengths of . The Portuguese man o' war's (Physalia physalis) tentacles can attain a length of up to . On 6 April 2020 the Schmidt Ocean Institute announced the discovery of a giant Apolemia siphonophore in submarine canyons near Ningaloo Coast, measuring 15 m (49 ft) diameter with a ring approximately 47 m (154 ft) long, claiming it was possibly the largest siphonophore ever recorded. Sponges (Porifera)

The largest known species of sea sponge is the giant barrel sponge, Xestospongia muta. These massively built sponges can reach  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. Calcareous sponges (Calcarea)
The largest known of these small, inconspicuous sponges is probably the species Pericharax heteroraphis, attaining a height of . Most calcareous sponges do not exceed  tall. Hexactinellid sponges (Hexactinellida)
A relatively common species, Rhabdocalyptus dawsoni, can reach a height of  once they are of a very old age. This is the maximum size recorded for a hexactinellid sponge. See also
 Largest prehistoric animals
 Megafauna
 Largest organisms

References

Animals

Heaviest or most massive organisms