Largest and heaviest animals

The largest animal currently alive, as well as the largest animal to ever exist, is the blue whale. The biggest blue whale ever measured weighed 190 tonnes and was about 27.6 metres (91 ft) long. Some blue whales have been even longer, up to 33.6 metres (110 ft), but their weight is not known. Scientists think some of these giants could have weighed as much as 250 tonnes or more.

The longest animal alive today is the lion's mane jellyfish, which can stretch up to 120 feet (36.6 m). On land, the African bush elephant is the largest living animal. These elephants live in many open areas of Africa, and males usually weigh around 6 tonnes (13,000 lb). The biggest elephant ever found was seen in Angola in 1974. This amazing elephant was very big, measuring about 10.67 metres (35.0 ft) from its trunk to its tail and standing about 3.96 metres (13.0 ft) tall at the shoulder. Scientists calculated that this elephant might have weighed between 10.4 and 12.25 tonnes.

Some animals that lived long ago were also extremely huge. One of these was a type of dinosaur called a sauropod, and some scientists think it could have weighed between 110–170 tons, maybe even up to 240 tons. Another huge animal was an ancient whale called Perucetus, which was first thought to be very heavy, but newer studies show it was smaller than previously believed. In April 2024, scientists identified a very large marine reptile named Ichthyotitan severnensis, which they believe was one of the biggest sea animals ever found, possibly even bigger than the blue whale. There may be an even bigger one, called 'Aust Colossus', but scientists are still learning more about its size.

Heaviest living animals

The heaviest living animals are all whales. It is hard to know their exact weights because no scale can hold a whole large whale. People sometimes use special factories to help weigh them, but it is still tricky. Most weights are figured out by measuring parts of whales after they are cut up, which can lead to mistakes. Scientists also use math to guess the weight of whales based on how long they are, but this can also be wrong.

Heaviest terrestrial animals

The heaviest animals that live on land are all mammals. The African elephant is now known as two different types: the African bush elephant and the African forest elephant.

Vertebrates

Mammals (Mammalia)

Main article: List of largest mammals

The blue whale is the largest animal of all time, with the heaviest known specimen weighing 190 tonnes. One blue whale reached a length of 33.6 metres. There were even longer blue whales, but they were not weighed.

The largest land mammal today is the African bush elephant. In the past, the largest land mammal was thought to be Paraceratherium, a rhino relative that may have stood up to 4.8 metres tall and weighed about 17 tonnes. More recent studies suggest the extinct elephant Palaeoloxodon namadicus might have been the largest, weighing up to 22 tonnes. Other studies point to Dzungariotherium as a possible contender, with estimates around 20.6 tonnes.

Stem-mammals (Synapsida)

The Late Triassic Lisowicia bojani from Poland was one of the largest non-mammalian synapsids, measuring 4.5 metres long and weighing around 9 tonnes. Another large synapsid was Anteosaurus from South Africa, which was 5 to 6 metres long and weighed between 500 and 600 kilograms.

Reptiles (Reptilia)

The largest living reptile is the saltwater crocodile of Southern Asia and Australia, with males typically reaching lengths of 3.9 to 5.5 metres. The largest recorded saltwater crocodile was 6.32 metres long and weighed about 1,360 kilograms.

Prehistoric reptiles were much larger. Giant crocodilomorphs like Deinosuchus and Sarcosuchus could weigh between 5 and 10 metric tons. The largest snake, Titanoboa, could grow up to 14.3 metres long. Marine reptiles like Archelon and Mosasaurus hoffmanni were also enormous, with Ichthyotitan possibly rivaling blue whales in size.

Dinosaurs (Dinosauria)

Dinosaurs were the largest animals to ever walk on land. The tallest and heaviest known dinosaur is an immature Giraffatitan from Tanzania, measuring 12 to 13.27 metres tall and weighing between 23.3 and 39.5 tonnes. The longest dinosaur was a 25 metre long Diplodocus.

Other large sauropods include Patagotitan, estimated at 37 to 40 metres long and 69 to 77 tonnes. Argentinosaurus might have weighed 100 tonnes, while Supersaurus could reach 34 metres in length.

The largest known theropod is the common ostrich. Among extinct theropods, the most complete Tyrannosaurus rex specimen was 12.3 to 12.8 metres long. Spinosaurus might have reached 15 metres in length and weighed 7.4 tonnes. Other large theropods include Giganotosaurus and Carcharodontosaurus.

Birds (Aves)

The largest living bird is the common ostrich from Africa, which can reach a height of 2.8 metres and weigh over 156 kilograms. The largest bird in history may have been the extinct elephant birds of Madagascar, which exceeded 3 metres in height and weighed up to 500 kilograms.

Other large birds included Dromornis stirtoni from Australia and the giant moa from New Zealand, which stood up to 3.7 metres tall.

Amphibians (Amphibia)

The largest living amphibian is the South China giant salamander, which can reach nearly 1.83 metres in length and weigh up to 64 kilograms. In the past, giant amphibian proto-tetrapods like Prionosuchus reached lengths of 9 metres.

Fish

The largest fish of all time was likely _Megalodon, estimated to have reached sizes of up to 24.3 metres. The largest living fish is the whale shark, with the largest individual reaching 18.8 metres in length. The largest living bony fish is the giant sunfish, with the largest recorded individual weighing 2,744 kilograms.

Invertebrate chordates

Tunicates (Tunicata)

Further information: Tunicata

The largest tunicate is Synoicum pulmonaria, found at depths between 20 and 40 metres and can be up to 14 centimetres in diameter. It is also found around Greenland and Newfoundland, though less commonly there.

Another large type is the pleurogona, with the biggest being Pyura pachydermatina. This tunicate can grow over a metre long and is off-white or reddish-purple in colour.

Cephalochordates (Leptocardii)

Further information: Leptocardii

The largest lancelet is the European lancelet (Branchiostoma lanceolatum), also called a "primitive fish". It can grow up to 6 centimetres long.

Thaliacea

The largest thaliacean is Pyrosoma atlanticum, which can grow up to 60 centimetres long. It is cylindrical and can produce a bright blue-green light when disturbed.

Doliolida (Doliolida)

The largest doliolida is also called Doliolida. These small, barrel-shaped animals are usually 1–2 centimetres long and can move quickly through the water.

Salps (Salpida)

The largest salp is Cyclosalpa bakeri, measuring 15 centimetres long. Salps can form colonies that look like a crown and can be up to 20 centimetres wide.

Larvaceans (Larvacea)

The largest larvacean is Appendicularia, with a body length of 1 centimetre not including its tail.

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 6 kg (13 lb). The longest echinoderm known is the sea cucumber Synapta maculata, with a slender body that can extend up to 3 m (9.8 ft). The biggest sea star is the brisingid sea star Midgardia xandaros, reaching a span of 1.4 m (4.6 ft).

Crinoids (Crinoidea)

The largest species of crinoid is the unstalked feather-star Heliometra glacialis, reaching a total width of 78 cm (31 in). In the past, crinoids grew much larger, with stalk lengths up to 40 m (130 ft) found in the fossil record.

Sea urchins and allies (Echinoidea)

The largest sea urchin is Sperosoma giganteum, which can reach a shell width of about 30 cm (12 in). The largest species found along the North America coast is the Pacific red sea urchin (Mesocentrotus franciscanus) where the shell can reach 19 cm (7.5 in).

Sea cucumbers (Holothuroidea)

The bulkiest species of sea cucumber are Stichopus variegatus and Thelenota anax, weighing several pounds and reaching a length of 1 m (3.3 ft) when fully extended. Synapta maculata can reach an extended length of 3 m (9.8 ft), but is extremely slender and weighs much less.

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 1 m (3.3 ft).

Sea stars (Asteroidea)

The heaviest sea star is Thromidia gigas, which can surpass 6 kg (13 lb) in weight, but only has a diameter of about 65 cm (2.13 ft). Despite its relatively small disk and weight, the long slender arms of Midgardia xandaros makes it the sea star with the largest diameter at about 1.4 m (4.5 ft).

Flatworms (Platyhelminthes)

The largest known species of tapeworm is the whale tapeworm, Polygonoporus giganticus, which can grow to over 30 m (98 ft).

Arrow Worms (Chaetognatha)

The largest arrow worm is Parasagitta setosa, which grows to a maximum length of 14 mm (0.55 in).

Segmented worms (Annelida)

The largest of the segmented worms is the African giant earthworm (Microchaetus rappi). 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).

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 55 m (180 ft).

Mollusks (Mollusca)

Both the largest mollusks and the largest of all invertebrates are the largest squids. The colossal squid (Mesonychoteuthis hamiltoni) is projected to be the largest invertebrate, with current estimates putting its maximum size at 12 to 14 m (39 to 46 ft) long. The giant squid (Architeuthis dux) may exceed the colossal squid in overall length including tentacles.

Aplacophorans (Aplacophora)

The largest known of these worm-like, shell-less mollusks are represented in the genus Epimenia, which can reach 30 cm (12 in) long.

Chitons (Polyplacophora)

The largest of the chitons is the gumboot chiton, Cryptochiton stelleri, which can reach a length of 33 cm (13 in) and weigh over 2 kg (4.4 lb).

Bivalves (Bivalvia)

The largest of the bivalve mollusks is the giant clam, Tridacna gigas. This creature weighed 270 kg (600 lb), had an axial length of 1.14 m (3.7 ft) and depth of 0.75 m (2.5 ft).

Gastropods (Gastropoda)

The living gastropod species that has the largest (longest) shell is Syrinx aruanus with a maximum shell length of 0.91 m (3.0 ft). The largest shell-less gastropod is the giant black sea hare (Aplysia vaccaria) at 0.99 m (3.2 ft) in length.

Cephalopods (Cephalopoda)

The largest confirmed weight of a giant octopus is 74 kg (163 lb), with a 7 m (23 ft) arm span.

Roundworms (Nematoda)

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.

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).

Water bears (Tardigrada)

The largest tardigrade is Echiniscoides sigismundi, which is less than 2 mm (0.079 in) long.

Arthropods (Arthropoda)

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 heaviest is the American lobster (Homarus americanus), with the largest verified specimen weighing 20 kg (44 lb).

Arachnids (Arachnida)

Spiders (Araneae)

The largest species of arachnid by length is probably the giant huntsman spider (Heteropoda maxima) of Laos.

Scorpions (Scorpiones)

The largest of the scorpions is the species Heterometrus swammerdami of the Indian subcontinent, which have a maximum length of 29.2 cm (11.5 in).

Thecostracans (Thecostraca)

The largest known thecostracan Facetotecta y-larvae are Hansenocaris cristalabri, about 0.5 millimeters long.

Barnacles and allies (Cirripedia)

The largest barnacle is Balanus nubilus, reaching a diameter of 15 cm (6 in) and a height of up to 30 cm (12 in).

Crustaceans (Crustacea)

The largest crustacean is the Tasmanian giant crab (Pseudocarcinus gigas), with a weight of 13 kilograms (29 lb). The largest mantis shrimp in the world is Lysiosquillina maculata. Tasmanian giant freshwater crayfish (Astacopsis gouldi) can weigh 5 kilograms (11 lb) and over 80 centimetres (31 in) long.

Branchiopods (Branchiopoda)

The largest of these primarily freshwater crustaceans is probably Branchinecta gigas, which can reach a length 10 cm (3.9 in).

Barnacles and allies (Maxillopoda)

The largest species is Pennella balaenopterae, a copepod specialising in parasitising marine mammals. The largest of the barnacles is the giant acorn barnacle, Balanus nubilis, reaching 7 cm (2.8 in) in diameter and 12.7 cm (5.0 in) 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 3 cm (1.2 in).

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 4.5 cm (1.8 in).

Horseshoe crabs (Xiphosura)

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.

Sea spiders (Pycnogonida)

The largest of the sea spiders is the deep-sea species Colossendeis colossea, attaining a leg span of nearly 60 cm (2.0 ft).

Trilobites (Trilobita)

Some of these extinct marine arthropods exceeded 60 cm (24 in) in length. An isolated pygidium of Hungioides bohemicus implies that the full animal was 90 cm (35 in) long.

Myriapods (Myriapoda)

Centipedes (Chilopoda)

The biggest of the centipedes is Scolopendra gigantea of the neotropics, reaching a length of 33 cm (13 in).

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.

Symphylans (Symphyla)

The largest known symphylan is Hanseniella magna, originating in Tasmanian caves, which can reach lengths from 25 mm (0.98 in) up to 30 mm (1.2 in).

Insects (Insecta)

The heaviest insect is almost certainly a species of beetle. 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.

Cockroaches and termites (Blattodea)

The largest cockroach by body mass is the Australian giant burrowing cockroach (Macropanesthia rhinoceros).

Beetles (Coleoptera)

The beetles are the largest order of organisms on earth. The most massive species are the Goliathus, Megasoma and Titanus beetles.

Earwigs (Dermaptera)

The largest of the earwigs has been the Saint Helena giant earwig (Labidura herculeana).

True flies (Diptera)

The largest species of this order is the neotropical species Gauromydas heros.

Mayflies (Ephemeroptera)

The largest mayflies are members of the genus Proboscidoplocia from Madagascar.

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.

Ants and allies (Hymenoptera)

The largest of the ants are the females of the African Dorylus helvolus, reaching a length of 5.1 cm (2.0 in) and a weight of 8.5 g (0.30 oz).

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 of any living insect.

Cnidarians (Cnidaria)

The lion's mane jellyfish (Cyanea capillata) is the largest cnidarian species. The largest known specimen had a bell diameter of 2.5 m (8.2 ft), a weight of 150 kg (330 lb). The tentacles of this specimen were as long as 37 m (121 ft).

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 60 cm (2.0 ft).

Communities of coral can be truly massive, with a clonal colony of Pavona clavus over 32 by 34 meters — the size of two basketball courts.

Hydrozoans (Hydrozoa)

The colonial siphonophore Praya dubia can attain lengths of 40–50 m (130–160 ft). The Portuguese man o' war's (Physalia physalis) tentacles can attain a length of up to 50 m (160 ft).

Box jellyfishes (Chirodropida)

The largest box jellyfish Chironex fleckeri is the largest of the cubozoans. Its bell usually reaches about 16 cm (6.3 in) in diameter but can grow up to 35 cm (14 in).

Sponges (Porifera)

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.