'' is the longest known echinoderm.
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. ==== 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. 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. ==== Sea stars (
Asteroidea) ==== , the heaviest sea star and largest echinoderm by weight :The heaviest sea star is
Thromidia gigas from the
Indo-Pacific, which can surpass in weight, but only has a diameter of about . ;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 . === Arrow Worms (
Chaetognatha) === , the longest arrow worm The largest arrow worm is
Parasagitta setosa, which grows to a maximum length of , its tail being up to a quarter of this length.
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.
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 . , the largest bivalve
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 . ==== Gastropods (
Gastropoda) ==== '' is the largest land snail :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 . 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. 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).
Water bears (Tardigrada) '', the largest water bear The largest
tardigrade is
Echiniscoides sigismundi, which is less than long. Typical tardigrades are about long. Only the larger tardigrades are visible to the naked eye, but since they're also transparent, magnification is needed to see them.
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 . 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 . ===== 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 . and the aquatic
Brontoscorpio, at up to which is only known from a free finger. ===== Pseudoscorpions (
Pseudoscorpiones) ===== : The largest pseudoscorpion is
Garypus titanius, from Ascension island, which can be long.
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 and a height of up to , and containing the largest known
muscle fibres. ==== Crustaceans (
Crustacea) ==== (
see below) 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 . ===== 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. ==== 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 wētās (
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 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. 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 of individuals are still extant. ===== True flies (
Diptera) ===== '', the largest fly :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 . ===== True bugs (
Hemiptera) ===== walking over land :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 . '', the largest bee. ===== 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 . 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. 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. Found in the
Early Cretaceous sedimentary rocks,
Makarkinia adamsi had wings nearly in length, implying a wingspan similar to the present-day largest moths. ; Dragonflies and damselflies (
Odonata) :The largest species of Odonata is the
damselfly Megaloprepus caerulatus of the
neotropics, attaining a size of as much as across the wings and a body length of over . 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 wētās) is the
katydid Macrolyristes corporalis of Southeast Asia which can range up to with its long legs extended and can have a wingspan of . ; (
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. ;Caddisflies (
Trichoptera) :The largest of the small, moth-like caddisflies is
Eubasilissa maclachlani. This species can range up to across the wings. ;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. ;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 . ;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 . ;Angel insects (
Zoraptera) :The largest angel insect species,
Hubbard's angel insect (
Zorotypus hubbardi), grows up to in length. ;Silverfish and allies (
Zygentoma) :The largest extant silverfish is
Acrotelsa collaris, at up to .
Cnidarians (Cnidaria) , one of the longest extant animals 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 specimen were as long as and were projected to have a tentacular spread of about making it one of the longest extant animals. 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 , even though the individual polyps are quite small. In 2024, the largest ever was found off
Malaulalo island in the Solomon Islands, 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 . 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 diameter with a ring approximately long, claiming it was possibly the largest siphonophore ever recorded.
Stygiomedusa, commonly known as the
giant phantom jelly, is the only species in the
monotypic genus of
deep sea jellyfish,
Stygiomedusa. It is in the
Ulmaridae family. With only around 110 sightings in 110 years, it is rarely seen, but is believed to be widespread throughout the world, with the exception of the
Arctic Ocean. ;Box jellyfishes (
Chirodropida) The largest box jellyfish
Chironex fleckeri is the largest of the cubozoans (collectively called box jellyfish), many of which may carry toxic venom. Its bell usually reaches about in diameter but can grow up to . Each of the four corners of the bell trails a cluster of 15
tentacles. 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 ==