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Cephalopods vary enormously in size. The smallest are only about long and weigh less than at maturity, while the largest—the
giant In folklore, giants (from Ancient Greek: ''gigas'', cognate giga-) are beings of human-like appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''giant'' is first attested in 1297 fr ...
and
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
s—can exceed in length and weigh close to half a tonne (), making them the largest living
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s. Living species range in mass more than three-billion-fold, or across nine
orders of magnitude An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...
, from the lightest hatchlings to the heaviest adults. Certain cephalopod species are also noted for having individual body parts of exceptional size. The giant and colossal squids, for example, have the largest known eyes among living animals. Nilsson ''et al.'', 2012:683 Cephalopods were at one time the largest of all organisms on Earth, and numerous species of comparable size to the largest present day squids are known from the
fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
, including enormous examples of ammonoids, belemnoids,
nautiloid Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded specie ...
s, orthoceratoids, teuthids, and vampyromorphids. In terms of mass, the largest of all known cephalopods were likely the giant shelled ammonoids and
endocerid Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early Ordovician possibly to the Late Silurian ...
nautiloids, Teichert & Kummel, 1960:6 though perhaps still second to the largest living cephalopods when considering tissue mass alone. Vermeij, 2016 Giant cephalopods have fascinated humankind since time immemorial. The earliest surviving records are perhaps those of
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
and
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ' ...
, both of whom described squids of very large size. Tales of giant squid have been common among mariners since ancient times, and may have inspired the monstrous kraken of Nordic legend, said to be as large as an island and capable of engulfing and sinking any ship. Similar tentacled
sea monster Sea monsters are beings from folklore believed to dwell in the sea and often imagined to be of immense size. Marine monsters can take many forms, including sea dragons, sea serpents, or tentacled beasts. They can be slimy and scaly and are of ...
s are known from other parts of the globe, including the
Akkorokamui The is a gigantic octopus-like monster from Ainu folklore, similar to the Nordic Kraken, which supposedly lurks in Uchiura Bay in Hokkaido. It is said that its enormous body can reach sizes of up to in length. Its name can be translated as ...
of Japan and
Te Wheke-a-Muturangi In Māori mythology, Te Wheke-a-Muturangi is a monstrous octopus destroyed in Whekenui Bay, Tory Channel or at Patea by Kupe the navigator. The octopus was a pet or familiar of Muturangi, a powerful tohunga of Hawaiki. The wheke was nonet ...
of
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. The
Lusca In Caribbean folklore, the Lusca is a name given to a sea monster said to exist in the region of the blue holes nearby Andros, an island in the Bahamas. Description It is described as a giant octopus, a giant cuttlefish, or a half dragon, half oc ...
of the Caribbean and Scylla in
Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...
may also derive from giant squid sightings, as might eyewitness accounts of other sea monsters such as
sea serpent A sea serpent or sea dragon is a type of dragon sea monster described in various mythologies, most notably Mesopotamian (Tiamat), Judaeo-Christian (Leviathan), Greek (Cetus, Echidna, Hydra, Scylla), and Norse (Jörmungandr). Mythology and fo ...
s. Size, and particularly maximum size, continues to be one of the most interesting aspects of cephalopod science to both the general public and researchers in the field. This is evidenced by the regular coverage given to the giant squid—and more recently, the colossal squid—in both the popular press and academic literature. Due to its status as a
charismatic megafauna Charismatic megafauna are animal species that are large—in the relevant category that they represent—with symbolic value or widespread popular appeal, and are often used by environmental activists to gain public support for environmentalist go ...
l species, the giant squid has been proposed as an emblematic animal for marine invertebrate conservation. Life-sized models of the giant squid are a common sight in
natural history museum A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. ...
s around the world, and preserved specimens are much sought after for display. Cephalopods vastly larger than either giant or colossal squids have been postulated at various times. Perhaps the most notable of these is the so-called St. Augustine Monster, a large carcass weighing several tonnes that washed ashore on the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
coast near St. Augustine,
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
, in 1896. Zoologist
Addison Emery Verrill Addison Emery Verrill (February 9, 1839 – December 10, 1926) was an American invertebrate zoologist, museum curator and university professor. Life Verrill was born on February 9, 1839 in Greenwood, Maine, the son of George Washington Verrill ...
of
Yale Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wor ...
, at the time the country's foremost authority on cephalopods, was initially convinced that it represented a previously unknown species of
gigantic octopus The kraken () is a legendary sea monster of enormous size said to appear off the coasts of Norway. Kraken, the subject of sailors' superstitions and mythos, was first described in the modern age at the turn of the 18th century, in a travelog ...
, and even proposed for it the scientific name ''Octopus giganteus''. However, having received tissue samples he quickly retracted his original opinion, identifying it instead as the remains of a
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
. Nevertheless, the possible existence of such a gargantuan octopus was taken seriously well into the 20th century, until reanalyses in 1995 and 2004 of the original tissue samples—together with those of other similar carcasses—showed conclusively that they were all masses of the collagenous matrix of whale blubber. Cephalopods of enormous size have featured prominently in fiction. Some of the best known examples include the giant squid from Jules Verne's 1870 novel ''
Twenty Thousand Leagues Under the Sea ''Twenty Thousand Leagues Under the Seas'' (french: Vingt mille lieues sous les mers) is a classic science fiction adventure novel by French writer Jules Verne. The novel was originally serialized from March 1869 through June 1870 in Pierre- ...
'' and its various film adaptations; the giant octopus from the 1955
monster movie A monster movie, monster film, creature feature or giant monster film is a film that focuses on one or more characters struggling to survive attacks by one or more antagonistic monsters, often abnormally large ones. The film may also fall under ...
''
It Came from Beneath the Sea ''It Came from Beneath the Sea'' is a 1955 American science fiction monster film from Columbia Pictures, produced by Sam Katzman and Charles Schneer, directed by Robert Gordon, that stars Kenneth Tobey, Faith Domergue, and Donald Curtis. The ...
''; and the giant squid from
Peter Benchley Peter Bradford Benchley (May 8, 1940 – February 11, 2006) was an American author, screenwriter, and ocean activist. He is known for his bestselling novel '' Jaws'' and co-wrote its film adaptation with Carl Gottlieb. Several more of his works ...
's 1991 novel '' Beast'' and the TV film adaptation of the same name.


Size in teuthology


Mantle length

Mantle length (ML) is the standard size measure for
coleoid Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e., octopuses, squid and cuttlefish). Unlike its extant sister group, Nautiloidea, whose ...
cephalopods ( shell diameter being more common for
nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in ...
es) and is almost universally reported in the scientific literature. The mantle is the cephalopod's "body", lying posterior to the head and enclosing the
viscera In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...
l mass and
mantle cavity The mantle (also known by the Latin word pallium meaning mantle, robe or cloak, adjective pallial) is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of ...
, the latter being used for locomotion by
jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operatin ...
. Unless otherwise indicated, mantle length is measured
dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
over the midline of the mantle (sometimes specified as ''dorsal mantle length'', DML). It is a straight-line measure, not measured over the curve of the body. In
Decapodiformes Decapodiformes is a superorder of Cephalopoda comprising all cephalopod species with ten limbs, specifically eight short arms and two long tentacles. It is hypothesized that the ancestral coleoid had five identical pairs of limbs, and that one ...
(ten-limbed cephalopods), mantle length is measured from the anterior edge of the mantle (near the head), to the posterior end of the mantle or the apex of the united
fins A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
, whichever is longer. In
Octopodiformes Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid (as is the case in octopuses) or modifyin ...
(eight-limbed cephalopods), the anterior edge of the mantle is not clearly delimited dorsally due to advanced head–mantle fusion, and mantle length is therefore taken from the midpoint between the eyes to the posterior end of the mantle. When ''ventral'' mantle length is meant instead of dorsal this is always specified as such and abbreviated VML. Roper & Voss, 1983:58 As an indication of overall size, mantle length is generally considered more reliable than total length because
cephalopod limb All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles. Description In the scientific ...
s may easily be stretched beyond their natural length and are often damaged or missing in preserved specimens (this is particularly true of the long
tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...
of many squid species). Nevertheless, mantle length is not equally applicable to all species. Certain benthic octopuses such as '' Callistoctopus ornatus'' are able to elongate and retract their mantles and therefore mantle length measurements, even when taken from a live specimen, may vary considerably. Another problematic case is that of the gelatinous cirroteuthids, whose weakly muscled mantles are prone to substantial shrinkage during preservation. The interocular distance may be a more reliable standard for this group.


Total length

Total length (TL) is measured along the
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...
midline with the limbs outstretched and in line with the body axis. It is the greatest measurable extent of a specimen from the posterior end of the mantle or
fins A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
(or
tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
, if present) to the apex of the longest limb. It is recommended that arms and tentacles be measured in a relaxed state so as not to exaggerate their length, but historically this practice was not always followed and some of the more extreme published
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
measurements have been attributed to artificial lengthening of the tentacles. O'Shea & Bolstad, 2008 Although total length is often mentioned in relation to the largest cephalopod species, it is otherwise seldom used in teuthology. As with mantle length, it is a straight-line measure. Total length is not to be confused with arm span—also known as ''arm spread'', ''radial span'', or ''radial spread''—which may be much larger and is often reported for octopuses (for which the arms usually constitute the vast majority of the length). In squids, total length is inclusive of the feeding tentacles, which in some species may be longer than the mantle, head, and arms combined ( chiroteuthids such as '' Asperoteuthis acanthoderma'' being a prime example). A related measure is standard length (SL), which is the combined length of the mantle, head, and arms, excluding the often long feeding tentacles. This measure is particularly useful for species such as the giant squid, where almost the entire bulk of the animal takes up less than half of its total length.


Mass

Mass (often abbreviated WT for 'weight') is reported far less frequently than either mantle or total length, and accurate records do not exist for all of the large cephalopod species. It can also vary widely depending on the state of the specimen at the time of weighing (for example, whether it was measured live or dead, wet or dry, frozen or thawed, pre- or post-fixation, with or without egg mass, and so on).


Methods of size determination

In contrast to the vast majority of living cephalopods, which are wholly soft-bodied, size determination of the few surviving shelled species (in terms of shell diameter) is comparatively straightforward and can be accomplished with a high level of precision. Whatever the type of cephalopod, in the absence of whole specimens, size can often be estimated from only partial remains. For example,
cephalopod beak All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like f ...
s can be used for mantle length, total length and body mass estimation, and this method has notably been used to estimate the maximum size of the
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
. The lower rostral length (LRL) of the beak is often used for this purpose. The rostral length of the lower and upper beaks is the standard measure of beak size in
Decapodiformes Decapodiformes is a superorder of Cephalopoda comprising all cephalopod species with ten limbs, specifically eight short arms and two long tentacles. It is hypothesized that the ancestral coleoid had five identical pairs of limbs, and that one ...
; hood length is preferred for
Octopodiformes Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid (as is the case in octopuses) or modifyin ...
. Mantle length has been estimated from video recordings of squid in the wild.


Early life stages


Hatchlings

Hatchlings of '' Idiosepius thailandicus'', possibly the smallest extant cephalopod species at maturity, have a mantle length of around . The closely related '' Idiosepius pygmaeus'' weighs only upon hatching and increases in weight to as it reaches maturity in 50 days. Even smaller are the hatchlings of the commercially important ''
Illex illecebrosus ''Illex illecebrosus'', commonly known as the northern shortfin squid, is a species of neritic squids in the family Ommastrephidae. Squids of the genus Illex account for 65% of the world’s cephalopod captures. Illex is formed by four taxa dis ...
'', with a mass of . Hatchlings of the
giant Pacific octopus The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus ''Enteroctopus''. Its spatial distribution includes the coastal North Pacific, along Mexico ...
(''Enteroctopus dofleini'')—one of the two largest octopus species—weigh on average. At the other extreme are
nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in ...
es, which upon hatching typically have a shell diameter of or more (depending on the species), the largest hatchling size among extant invertebrates. Hatchlings of '' Nautilus belauensis'', one of the larger species, are estimated to weigh on the order of and mature at around after almost 4000 days, or around 11 years.


Smallest adult size

The smallest adult size among living cephalopods is attained by the so-called pygmy squids, '' Idiosepius'', and certain diminutive species of the genus '' Octopus'', both of which weigh less than at maturity. '' Idiosepius thailandicus'' is perhaps the smallest of all, with females averaging in mantle length and males . Average wet weights are around , respectively. Other tiny species include members of the bobtail squid family Sepiolidae; the myopsid squid genera '' Australiteuthis'' and '' Pickfordiateuthis''; the oegopsid squid genera '' Abralia'' and '' Abraliopsis''; the pygmy cuttlefish '' Sepia pulchra''; and the ram's horn squid, ''
Spirula spirula ''Spirula spirula'' is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus ''Spirula'', the family Spirulidae, and the order Spirulida. Because of the shape of its internal shell, it is commonly kn ...
''.


Male dwarfism

The octopod superfamily Argonautoidea is characterised by markedly dwarfed males. The four extant genera of the group are '' Argonauta'', '' Haliphron'', '' Ocythoe'', and '' Tremoctopus'', all of which are exclusively
pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...
. The greatest disparity in the size of the sexes is seen in the blanket octopuses of the genus ''Tremoctopus''. Norman ''et al.'' (2002) reported a fully mature male '' Tremoctopus violaceus'' measuring in total length and weighing a mere . By comparison, the large females of this species reach total lengths of and probably some in weight. This is the most extreme
sexual size dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
known among non-microscopic animals, with mature females being at least 10,000 times heavier than males, and likely up to 40,000 times heavier. The related genera ''Argonauta'' and ''Ocythoe'' have similarly small males, but the females are not nearly as large as those of ''Tremoctopus'', and the size dimorphism is therefore less pronounced. The females of the fourth argonautoid genus, ''Haliphron'', are the largest of all (and possibly the largest octopuses of any kind), but the males are also much larger, at up to .


Extinct taxa

Numerous species of so-called micromorphic ammonites are known. '' Maximites'' from the
Upper Carboniferous Upper may refer to: * Shoe upper or ''vamp'', the part of a shoe on the top of the foot * Stimulant, drugs which induce temporary improvements in either mental or physical function or both * ''Upper'', the original film title for the 2013 found f ...
is the smallest known ammonoid. Adult specimens reached only in shell diameter.


Maximum size


Scientifically validated records

Squids are the largest living cephalopods in terms of each of mantle length, total length, and mass, with the largest species by at least two of these measures being the
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
, ''Mesonychoteuthis hamiltoni''. Reaching an estimated in mantle length and in total length, and weighing as much as , this species is also the largest of all extant
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s. The only other squid that approaches these dimensions is the
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
of the genus ''Architeuthis'', with females up to , in mantle length, and possibly as much as in total length, making it likely the longest of all cephalopods. McClain ''et al.'', 2015 The two largest octopus species—''
Enteroctopus dofleini The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus ''Enteroctopus''. Its spatial distribution includes the coastal North Pacific, along Mexico ...
'' and ''
Haliphron atlanticus The seven-arm octopus (''Haliphron atlanticus'') is one of the two largest known species of octopus; based on scientific records, it has a maximum estimated total length of and mass of . The only other similarly large extant species is the gian ...
''—can both exceed , and the former has a maximum total length of more than . Cirrate (finned) octopods can also reach a large size, with the largest captured specimen likely being a '' Cirrothauma magna'' of total length and mantle length, though observations from submersibles suggest that members of this group can exceed in total length. Members of the other cephalopod groups are substantially smaller, although the largest cuttlefish can exceed in weight and in mantle length. Cephalopods of comparable size to the largest present day squid are known from fossil remains, including enormous examples of ammonoids, belemnoids,
nautiloid Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded specie ...
s, orthoceratoids, teuthids, and vampyromorphids.


Colossal squid (''Mesonychoteuthis hamiltoni'')

Though a substantial number of
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
(''Mesonychoteuthis hamiltoni'')
remains Remains or The Remains may refer to: Music *The Remains (band), a 1960s American rock band *The Ramainz, originally The Remains, a Ramones tribute band Albums * ''Remains'' (Alkaline Trio album), 2007 * ''Remains'' (Annihilator album), 1997 * ' ...
have been recorded ( Xavier ''et al.'', 1999 collated 188 geographical positions for whole or partial specimens caught by commercial and scientific fisheries), very few adult or subadult animals have ever been documented, making it difficult to estimate the maximum size of the species. McClain ''et al.'' (2015) stated that only 12 "complete" specimens were known. The largest known complete specimen of the colossal squid was a mature female captured in the
Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who ...
in February 2007. Its weight was initially estimated at , its mantle length at , and its total length at . Once completely thawed the specimen was found to weigh , but to measure only in mantle length and in total length. nonymous It is likely that the specimen, and particularly its tentacles, shrank considerably ''post mortem'' as a result of dehydration, having been kept in a freezer for 14 months. (As reported by the Museum of New Zealand Te Papa Tongarewa, specimens of ''
Nototodarus sloanii ''Nototodarus sloanii'' is a species of squid commonly known as the New Zealand arrow squid or Wellington flying squid. It is also known by its Māori name of wheketere. It is a favoured prey species of a number of marine mammals and diving bird ...
'', the New Zealand arrow squid, can shrink by as much as 22% when dehydrated with alcohol solutions.) The colossal squid specimen contracted by a further 5% after several years in preservative fluid (first
formalin Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
and later
propylene glycol Propylene glycol (IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. Containing two alcohol groups, it is classed as a diol. It i ...
). The fins of the 2007 Ross Sea specimen measured around across and it had a mantle width of . The arms ranged in length from , while the two tentacles were around long. Beaks recovered from sperm whale stomachs indicate the existence of animals surpassing even the 2007 Ross Sea specimen. That specimen had a lower rostral length (LRL) of and weighed , nonymous where as the submature female from 2003 had a LRL of . By comparison, the largest known colossal squid beak from a sperm whale stomach measured in LRL. Though the number of large colossal squid specimens known to science is too small to get a good idea of the relationship between beak size and overall body size, a beak of such enormity indicates a truly massive animal weighing perhaps as much as . However, the scaling relationship for this species shows considerable latitude, as demonstrated by a beak of LRL extracted from an animal weighing only .


Giant squid (''Architeuthis dux'')

The maximum size of the
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
(''Architeuthis dux'') has long been a subject of both popular debate and academic inquiry. Unlike the colossal squid, the giant squid is known from a substantial number of mature specimens. The total number of recorded specimens (across all developmental stages) approaches a thousand, with approximately 700 documented , of which around 460 had been measured in some way. Paxton, 2016a This number has since increased substantially, with 57 specimens recorded from Japanese waters during an exceptional 15-month period between 2014 and 2015. Kubodera ''et al.'', 2016 Based on a 40-year data set of more than 50 giant squid specimens, Roper & Shea (2013:114) suggest an average total length at maturity of and a "rarely encountered maximum length" of . Of the nearly 100 specimens examined by
Clyde Roper Clyde F. E. Roper (born 1937) is a zoologist at the National Museum of Natural History in Washington, D.C. He has organised a number of expeditions to New Zealand to study giant squid, including in 1997 and 1999. He graduated from Transylvania Uni ...
, the largest was " long". O'Shea & Bolstad (2008) give a maximum total length of for females based on the examination of more than 130 specimens, measured ''post mortem'' and relaxed, as well as beaks recovered from sperm whales (which do not exceed the size of those found in the largest complete specimens). Steve O'Shea estimated the maximum total length for males at . O'Shea, 2003a Older records of or more were likely exaggerated by stretching of the long feeding tentacles or resulted from inadequate measurement methods such as pacing. O'Shea & Bolstad, 2008; Roper & Shea, 2013:113 O'Shea has stated that, given the available evidence, the highest
upper bound In mathematics, particularly in order theory, an upper bound or majorant of a subset of some preordered set is an element of that is greater than or equal to every element of . Dually, a lower bound or minorant of is defined to be an eleme ...
he would consider plausible for the giant squid's total length would be , and that the likelihood that there exist 20-metre giant squid is "so exceedingly remote that you couldn't justify the effort in writing about it". Bittel, 2016 Including the head and
arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...
but excluding the
tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...
(standard length, SL), the species very rarely exceeds according to O'Shea & Bolstad (2008). Paxton (2016a) considers to be the greatest reliably measured SL, based on a specimen reported by Verrill (1880a:192), and considers specimens of SL or more to be "very probable", but these conclusions have been criticised by giant squid experts. Greshko, 2016 O'Shea (2003a) put the maximum weight of female giant squid at , based on the examination of some 105 specimens as well as beaks recovered from sperm whales (which do not exceed the size of those found in the largest complete specimens). Giant squid are sexually size dimorphic, with the maximum weight for males estimated at , though heavier specimens have occasionally been reported (such as a specimen and a specimen). Roper & Jereb (2010a:121) give a maximum weight of up to , and "possibly greater". Discredited weights of as much as a
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
() or more are not uncommon in older literature (see below).


Other squid taxa

The third-heaviest extant squid species is '' Taningia danae'', also known as the Dana octopus squid. The largest well documented specimen is a 160 cm ML mature female reported by Roper & Vecchione (1993) from the North Atlantic. The original paper gave the mass of this specimen as , but according to Roper & Jereb (2010h:266) this figure is wrong and stems from a typographical error, the correct mass being . Roper & Vecchione (1993) were however consistent in their use of the 61.4 kg figure. Another similarly large specimen—a female weighing —was reported from northern Spanish waters by González ''et al.'' (2003:297) (see also initial reports). In July 2010, a sperm whale was photographed off the Azorean island of Faial with a large squid—likely ''T. danae''—in its mouth. The specimen's maximum width, from fin tip to fin tip, was estimated at ; this would approximate its mantle length. ''
Onykia robusta ''Onykia robusta'', also known as the robust clubhook squid and often cited by the older name ''Moroteuthis robusta'', is a species of squid in the family Onychoteuthidae. Reaching a mantle length of ,Norman, M.D. 2000. ''Cephalopods: A World ...
'', previously known as ''Moroteuthis robusta'' and sometimes called the robust clubhook squid, has a mantle length of up to . Some older records exceed this, such as the ML reported by Verrill (1876:237) from a specimen with a total length of (excluding the ends of the tentacles, which had been destroyed). Nesis (1987:192) likewise gave a maximum mantle length of , but Roper & Jereb (2010i:364) wrote that "this old record might be in error", with the species commonly growing to ML. Glaubrecht & Salcedo-Vargas (2004:66) provided a maximum total length of . Literature sources give a maximum weight of . There exist numerous published records of large individuals of this species. The
Humboldt squid The Humboldt squid (''Dosidicus gigas''), also known as jumbo squid or jumbo flying squid (EN), and Pota in Peru or Jibia in Chile (ES) is a large, predatory squid living in the eastern Pacific Ocean. It is the only known species of the genus ''D ...
(''Dosidicus gigas''), also known as the 'jumbo squid', grows to a maximum mantle length of at least , if not . The largest animals are found off the western coast of
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
; northern populations reach ML, and in general ML is more typical for the species. Roper ''et al.'', 2010b:301 Southern populations may have a total length approaching , and possibly up to . Again, specimens from the northern hemisphere are much smaller, with those off the
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
n coast reaching total lengths of less than . The Humboldt squid commonly attains a weight of around and can reach a maximum of . There are anecdotal reports of much larger individual animals, including from diver Scott Cassell, who has dived with Humboldt squid over 300 times (reportedly more than any other person). Cassell, 2005 '' Kondakovia longimana'', sometimes known as the giant warty squid, is a little known species with a circum- Antarctic distribution in the
Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...
. The largest complete specimen, found floating at the surface off the South Orkney Islands, had a mantle length of , Lynnes & Rodhouse, 2002:1087; see also Carrington, 2000 but a damaged female specimen with an estimated mantle length of around is known. The largest complete specimen had a wet weight of . The species' maximum weight has been estimated at .


Largest octopi

The
giant Pacific octopus The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus ''Enteroctopus''. Its spatial distribution includes the coastal North Pacific, along Mexico ...
(''Enteroctopus dofleini'') grows to more than in total length and at least in mantle length. Cosgrove (1987) and Cosgrove & McDaniel (2009:69) gave a maximum confirmed weight of for a live specimen collected in the mid-1960s. Norman ''et al.'' (2014:124) accept a maximum weight of at least , which approximates the reported for a specimen caught off Santa Barbara,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, in 1945, of which photographic evidence survives. Cosgrove & McDaniel, 2009:67–69 No specimens approaching this size have been reported since the middle of the 20th century, with recent specimens very rarely exceeding . Cosgrove & McDaniel, 2009:71 It is possible that the maximum size of the species has decreased over this period, perhaps due to bioaccumulation of
toxicant A toxicant is any toxic substance, whether man-made or naturally occurring. By contrast, a toxin is a poison produced naturally by an organism (e.g. plant, animal, insect). The different types of toxicants can be found in the air, soil, water, or ...
s (see below). In 2002, a giant specimen of ''
Haliphron atlanticus The seven-arm octopus (''Haliphron atlanticus'') is one of the two largest known species of octopus; based on scientific records, it has a maximum estimated total length of and mass of . The only other similarly large extant species is the gian ...
'', the seven-arm octopus, was caught by fishermen trawling at a depth of off the eastern
Chatham Rise The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some from near the South Island in the west, to the Chatham Islands in the east. It is New Zealand's most productiv ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. This specimen, the largest of this species and possibly of all octopuses, was the first validated record of ''Haliphron'' from the South Pacific. It had a mantle length of , a total length of , and a weight of , although it was incomplete. The total length of the specimen, when complete, has been estimated at , and its weight at .


Extinct taxa

Certain extinct cephalopods rivalled or even exceeded the size of the largest living species. In particular, the subclass Ammonoidea is known to have included a considerable number of species that may be considered "giant" (defined by Stevens, 1988 as those exceeding in shell diameter). The largest confirmed ammonite, a specimen of '' Parapuzosia seppenradensis'' discovered in a
German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
quarry in 1895, measures in diameter, though its living chamber is largely missing. The diameter of the complete shell has been estimated at , assuming the living chamber took up one-fourth of the outer whorl. Teichert & Kummel (1960:6) suggested an even larger original shell diameter of around for this specimen, assuming the body chamber extended for three-fourths to one full whorl. In 1971 a portion of an ammonite possibly surpassing this specimen was reportedly found in a
brickyard A brickyard or brickfield is a place or yard where bricks are made, fired, and stored, or sometimes sold or otherwise distributed from. Brick makers work in a brick yard. A brick yard may be constructed near natural sources of clay or on o ...
in
Bottrop Bottrop () is a city in west-central Germany, on the Rhine–Herne Canal, in North Rhine-Westphalia. Located in the Ruhr industrial area, Bottrop adjoins Essen, Oberhausen, Gladbeck, and Dorsten. The city had been a coal-mining and rail cent ...
, western Germany. A specimen found by Jim Rockwood, from the
Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. ...
near
Williston Lake Williston Lake is a reservoir created by the W. A. C. Bennett Dam and is located in the Northern Interior of British Columbia, Canada. Geography The lake fills the basin of the upper Peace River, backing into the Rocky Mountain Trench which is ...
,
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, was said to measure more than across, but was later determined to be a
concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...
. Heteromorph ammonites are known to have exceeded in length also, but since their shells were uncoiled to varying degrees, they were overall much smaller than the largest non-heteromorphs. The greatest lengths of all were reached by the orthocones of
endocerid Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early Ordovician possibly to the Late Silurian ...
nautiloid Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded specie ...
s such as ''
Cameroceras ''Cameroceras'' ("chambered horn") is a genus of extinct, giant orthoconic cephalopod that lived mainly during the Ordovician period. It first appears during the middle Ordovician, around 470 million years ago, and was a fairly common componen ...
'' and ''
Endoceras ''Endoceras'' (Ancient Greek for "inner horn") is an extinct genus of large, straight shelled cephalopods from the Middle and Upper Ordovician that gives its name to the Nautiloid order Endocerida. The cross section in the mature portion is slig ...
'', which may have exceeded , although their maximum size is uncertain; while the largest well documented endocerid fossil is likely the 3-metre-long () shell fragment housed at the
Museum of Comparative Zoology A museum ( ; plural museums or, rarely, musea) is a building or institution that cares for and displays a collection of artifacts and other objects of artistic, cultural, historical, or scientific importance. Many public museums make thes ...
,
Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...
, there are published reports of even larger specimens. Teichert (1927) mentioned specimens up to long from the
Middle Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. Th ...
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
of
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...
and Frey (1995:72) gave a maximum shell length of for the group. On the subject of endocerid size, nautiloid specialist Rousseau H. Flower wrote:
They are not all large, by any means, but specimens twelve feet [] in length have been collected, and fragments of greater diameter indicate a much greater maximum length. I am not wholly inclined to discredit a report of an endoceroid found in a quarry near Watertown, New York, Watertown New York, which was measured before it was broken up and found to attain a length of .
However, the uncoiled length of the largest ammonites far exceeds that of even these giant endocerids. '' Parapuzosia seppenradensis'', the largest known ammonite species, had an estimated maximum unrolled shell length of around . It was also possibly the heaviest of all known cephalopods, past or present, with an estimated live mass of , of which the shell would constitute 705 kg. By comparison, the largest endocerids may have weighed around . In terms of mass, these are the largest known
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s that have ever lived, though perhaps still second to the largest living cephalopods when considering tissue mass alone, since in shell-bearing species the vast majority of the living tissue is restricted to the body chamber, which occupies only a fraction of the internal shell volume. They might also be the largest—or at least longest—shell-bearing animals that have ever lived.


Historical claims


Misidentifications

The maximum sizes of certain cephalopod species, most notably the giant squid and giant Pacific octopus, have often been misreported and exaggerated. The literature on cephalopod size has been further muddied by the frequent misattribution of various squid specimens to the giant squid genus ''Architeuthis'', often based solely on their large size. In the academic literature alone, such misidentifications encompass at least the oegopsid families
Chiroteuthidae The Chiroteuthidae are a family of deep-sea squid, generally small to medium in size, rather soft and gelatinous, and slow moving. They are found in most temperate and tropical oceans, but are known primarily from the North Atlantic, North Pac ...
, Cranchiidae,
Ommastrephidae Ommastrephidae is a family of squid containing three subfamilies, 11 genera, and over 20 species. They are widely distributed globally and are extensively fished for food. One species, '' Todarodes pacificus'', comprises around half of the world ...
, Onychoteuthidae, and Psychroteuthidae. This situation is further confused by the occasional usage of the common name 'giant squid' in reference to large squids of other genera. Perhaps the most notable misidentification relates to a photograph taken some time before 1993 by diver H. Kubota off southern Japan. The image shows a large individual of ''
Onykia robusta ''Onykia robusta'', also known as the robust clubhook squid and often cited by the older name ''Moroteuthis robusta'', is a species of squid in the family Onychoteuthidae. Reaching a mantle length of ,Norman, M.D. 2000. ''Cephalopods: A World ...
'' (previously known as ''Moroteuthis robusta''), which appears to be sick or dying, alongside a diver in shallow water. A video of the same animal appeared in a Japanese made-for-television film. The image was published in the 1993 book ''European Seashells'' by Guido T. Poppe and Yoshihiro Goto, where it was identified as ''Architeuthis dux'', the giant squid, and said to have been taken in the North Atlantic. If true, this image would represent the first known photograph of a live giant squid. In ''
The Search for the Giant Squid ''The Search for the Giant Squid'' is a non-fiction book by Richard Ellis on the biology, history and mythology of the giant squid of the genus '' Architeuthis''. It was well received upon its release in 1998. Though soon rendered outdated by ...
'' (1998), Richard Ellis wrote:
For a moment, I thought that some obscure photograph had captured the most elusive image in natural history. Fortunately for those who have devoted their lives to searching for ''Architeuthis'', this was only an aberration, a case of mistaken identity.
It would be more than a decade before the true first photographs of a live giant squid in the wild were taken on 30 September 2004 by
Tsunemi Kubodera is a Japanese zoologist with the National Museum of Nature and Science. On September 30, 2004, Kubodera and his team became the first people to ''photograph'' a live giant squid in its natural habitat.Kubodera, T. & K. Mori 2005First-ever observa ...
and
Kyoichi Mori Kyoichi Mori ( Japanese: 森 恭一 ''Mori Kyoichi'') is a Japanese whale watcher who assisted Tsunemi Kubodera in taking the first photographs of a living giant squid in its natural habitat. He is a member of the Ogasawara Whale Watching Associ ...
. Kubodera and his team subsequently became the first to ''film'' a live ''adult'' giant squid on 4 December 2006, and the first to ''film'' a live giant squid ''in its natural habitat'' in July 2012. These milestones were preceded by the first footage of a live ( paralarval) giant squid in 2001, and the first image of a live adult giant squid on 15 January 2002. Since then, live giant squid have been photographed and filmed on a number of occasions.


Giant squid

Reports of giant squid (''Architeuthis dux'') specimens reaching or even exceeding in total length are widespread, but no animals approaching this size have been scientifically documented in recent times. This is despite there being hundreds of specimens available for study ( 700 documented as of 2015, of which 460 measured in some way), including numerous recent examples, such as the 57 specimens recorded from Japanese waters over a 15-month period in 2014–2015. It is now thought likely that such lengths were achieved by great lengthening of the two long feeding tentacles, analogous to stretching elastic bands, or resulted from inadequate measurement methods such as pacing. On the subject of the oft-cited maximum size of 18 metres—or 60 feet— Dery (2013) quoted giant squid experts Steve O'Shea and
Clyde Roper Clyde F. E. Roper (born 1937) is a zoologist at the National Museum of Natural History in Washington, D.C. He has organised a number of expeditions to New Zealand to study giant squid, including in 1997 and 1999. He graduated from Transylvania Uni ...
:
If this figure 5 ft or seems a little short of the Brobdingnagian claims made for ''Architeuthis'' in most
pop-science ''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...
stories about the animal, that's probably because virtually every general-interest article dutifully repeats the magic number of ''60'' feet. Steve O'Shea deplores the media's perpetuation of what he believes to be a credulity-straining exaggeration, based on the 19th-century biologist Thomas Kirk's eyeball estimate of a specimen's length. In a comment on the final draft of this article, O'Shea wrote, "Kirk ''paced'' it, in his own words, for he had no ruler/measure handy, and I believe this misrepresentation has been perpetuated enough; if they were foot-on-foot, as in heel directly to toe, I would accept 57 (or 58, whatever the precise figure was), but I think perpetuating this as fact any longer is doing a disservice to science." Roper, in his comments on the final draft of this article, was even more conservative, writing, "there are no ''confirmed'' records of giant squid longer than about 45 feet [] total length. Most are in the 25–35-foot [] range. I have examined specimens in museums and laboratories around the world—perhaps a 100 or so—and I believe the 60-foot number comes from fear, fantasy, and pulling the highly elastic tentacles out to the near breaking point when they are measured on the shore or on deck."


=Largest reported animals

= Paxton (2016a) investigated the maximum size of ''Architeuthis'' by performing a statistical analysis using data from literature records of giant squid specimens. He selected what he regarded as the largest size records for each of mantle length (ML), standard length (SL), and total length (TL). Paxton's study has been criticised by giant squid experts, who have called into question the reliability of some of the selected literature records. For mantle length, Paxton (2016a:83) considered the reported by Dell (1952:98) as the "longest measured", though "more reliably" the ML specimen from
Lyall Bay Lyall Bay is a bay and suburb on the south side of the Rongotai isthmus in Wellington, New Zealand. The bay is a popular surf beach, featuring a breakwater at the eastern end. It is home to two surf lifesaving clubs and has also been the site of ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
, documented by Kirk (1880:312). Paxton added: "A specimen from
Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label= Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It ...
is often mistakenly cited but consultation of the primary paper ( Staub, 1993) reveals an ill-defined length which is clearly not ML." The greatest measured ML of a giant squid recovered from a sperm whale is either the reported by Keil (1963:320) (though Paxton writes: "the account is confused and the 2.4 m figure probably refers to the head and ML combined") or the of a specimen that had been swallowed whole off the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
, detailed by Clarke (1955:589) and Clarke (1956:257). The "longest visually estimated" ML, according to Paxton, is the of a specimen apparently observed in the North Atlantic off
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
, attributed to a personal communication with T. Lipington. A more modest ML is also given, based on a sighting in the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...
sourced to the TV documentary of Lynch (2013). For standard length (excluding the
tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...
), Paxton (2016a:83) cited the of the " Three Arms specimen" documented by Verrill (1880a:192) as the "longest measured". Among specimens recovered from sperm whales, the longest "definitely measured" SL is the reported by Clarke (1956:257) and the longest "visually estimated" SL is the attributed to a photograph of a sperm whale with giant squid remains in its jaws, though Paxton conceded that it is " t clear how much/what portion of body was eaten". For the "longest visually estimated", more extreme supposed SLs of and are cited to Starkey (1963) and Ellis (1998a:246), respectively (the latter an eyewitness account by Dennis Braun). Paxton treated these last two size estimates as SLs as opposed to TLs because "squid do not generally leave their tentacles exposed except when grabbing prey and this appears to be the case for ''Architeuthis''". For total length, Paxton (2016a:83) considered three records as candidates for the "longest measured": the specimen of Berzin (1972:199), the specimen described by Kirk (1888) as ''Architeuthis longimanus''—a strangely proportioned animal that has been much commented on—and the " Thimble Tickle specimen" reported by Verrill (1880a:191), which is often cited as the largest giant squid ever recorded. Of the last one, Paxton wrote: "Sometimes mistakenly cited as but the source is clear that it is 55 ft long." The first two records, particularly that of Berzin, are more questionable, as Paxton explained:
The accuracy of the two longest measured TLs of 19 and 16.81 m from a specimen found in the gut of a sperm whale from the Indian Ocean and from the specimen from New Zealand in 1887, respectively, should also be questioned but again are certainly not impossible. The New Zealand specimen (named ''Architeuthis longimanus'' Kirk, 1888) clearly has the largest ratio of TL to ML ever known in ''Architeuthis'' ..which led O'Shea_&_Bolstad,_2008.html" ;"title="/nowiki> O'Shea & Bolstad, 2008">/nowiki> O'Shea & Bolstad, 2008/nowiki> to suggest that the length was paced out and/or there was extensive post-mortem stretching. However, a re-reading of the original paper suggests that the specimen, although initially paced out, was actually measured, nevertheless the TL is at the edge of the 99.9% prediction interval range ..and so it was certainly an unusual specimen. Berzin's (1972) Indian Ocean claim is suspect because of the roundness of the figure, the lack of detailed measurements and because in an associated photo, the mantle (whose length was not given) does not look very large compared to the men in the image. Consequently the measurement, if accurate, would represent another animal with very long tentacles.
However, as Paxton (2016a:86) pointed out, the genetic analysis of Winkelmann ''et al.'' (2013)—which concluded that there is likely a single, globally-distributed species of ''Architeuthis''—did not encompass these two specimens, and it is therefore possible that there exists a second, as yet unsampled, giant squid species with proportionately longer tentacles. The total length of the Berzin specimen was later confirmed to be erroneous; according to Valentin Yukhov, who was involved in the specimen's discovery, it should have read . Romanov ''et al.'', 2017 The misprint was reproduced in the English translation published the following year and was later propagated in a number of papers on giant squid. With the Berzin specimen not being as large as originally reported, the longest giant squid recovered from a sperm whale is the TL individual recorded by Clarke (1956:257) (this specimen also has the longest confirmed ML and SL of any giant squid from a sperm whale). Paxton considered the "longest visually estimated" TL to be the published by Murray (1874:121), from an eyewitness account by fisherman Theophilus Picot, who claimed to have struck the floating animal from his boat, causing it to attack. Picot managed to hack off one of its tentacles, which was subsequently examined by a number of authors. Perhaps the largest of all recorded giant squid specimens was the one found floating at the surface off Saint-Gilles, Réunion, on 4 March 2016. Although due to its great size the specimen could not be retrieved in its entirety, the head and arm crown were saved. Crucially, this meant the beak could be measured to estimate the mantle length and total length of the specimen. Using different
allometric scaling Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Julian Huxley in 1932. Overview Allo ...
equations, the lower rostral length of the beak, at , gave an estimated dorsal mantle length of and this, in turn, was used to estimate the total length at .


=Supposed sucker scars

= More extreme and outlandish giant squid size claims—belonging firmly in the realm of
cryptozoology Cryptozoology is a pseudoscience and subculture that searches for and studies unknown, legendary, or extinct animals whose present existence is disputed or unsubstantiated, particularly those popular in folklore, such as Bigfoot, the Loch Ness ...
—have appeared in the works of authors such as
Bernard Heuvelmans Bernard Heuvelmans (10 October 1916 – 22 August 2001) was a Belgian-French scientist, explorer, researcher, and writer probably best known, along with Scottish-American biologist Ivan T. Sanderson, as a founding figure in the pseudoscienc ...
,
Willy Ley Willy or Willie is a masculine, male given name, often a diminutive form of William or Wilhelm, and occasionally a nickname. It may refer to: People Given name or nickname * Willie Aames (born 1960), American actor, television director, and scr ...
, and
Ivan T. Sanderson Ivan Terence Sanderson (January 30, 1911 – February 19, 1973) was a British biologist and writer born in Edinburgh, Scotland, who became a naturalized citizen of the United States. Along with Belgian-French biologist Bernard Heuvelmans, San ...
. The existence of these gargantuan squids is often supported by reference to the giant circular scars sometimes found on sperm whales, which are assumed to have been inflicted by the suckers of struggling giant squid. Sometimes these claims are accompanied by extrapolations of body size based on the isometric upscaling of a "typical" giant squid. However, such scars are not necessarily of squid origin and may instead represent fungal growths or bite marks, with
sea lamprey The sea lamprey (''Petromyzon marinus'') is a parasitic lamprey native to the Northern Hemisphere. It is sometimes referred to as the "vampire fish". Description The sea lamprey has an eel-like body without paired fins. Its mouth is jawless, ...
s (''Petromyzon marinus'') being one possible source. Even in the case of genuine giant squid sucker marks it is possible that subsequent skin growth has enlarged them well beyond their original dimensions. Nevertheless, claims of enormous sucker scars are widespread in the literature. Richard Ellis collected some of "the more egregious examples" in his book, ''
The Search for the Giant Squid ''The Search for the Giant Squid'' is a non-fiction book by Richard Ellis on the biology, history and mythology of the giant squid of the genus '' Architeuthis''. It was well received upon its release in 1998. Though soon rendered outdated by ...
''. These include the claim of Dozier (1976) that "an ordinary giant squid of 50 feet [] leaves teeth-ringed sucker marks measuring between three and four inches [] across on a whale, but sperm whales have been captured with tentacle marks 18 inches [] across." L. Harrison Matthews's monographic treatment of the sperm whale, published in 1938, includes the following: "Nearly all male Sperm whales carry scars caused by the suckers and claws of large squids, scars caused by suckers up to 10 cm. [] in diameter being common. The claw marks take the form of scratches 2–3 m. [] in length, and appear to be of more frequent occurrence than sucker marks". Ellis (1998a:142) wrote that this 10 cm figure is "so much larger than any other recorded sucker dimensions that one suspects some sort of error, either in measuring or in transcription." The subject was covered in some detail by Wood (1982:192):
Measurements of , and even have been conjectured for giant squids from the size of sucker marks found on the skins of captured sperm whales, but it is dangerous to place too much reliance on this evidence. Verrill says the largest suckers on the tentacles of a long specimen measured 1 in [] in diameter, and those on a 52-footer [] about . #Daniel1925, Daniel (1925), however, examined sucker marks on the head of one cachalot which measured 3 in [] across, and others measuring up to in diameter have been found on the skins of sperm whales captured in the North Atlantic. Ivan Sanderson (1956) goes even further and claims that sucker marks over have been found on the heads of cachalots, but he does not explain how the poor whales managed to escape from the clutches of such colossi! The general consensus of opinion is that exceptionally large sucker marks, i.e. over in diameter, are old scars that have increased in size as the sperm whale grew.
Perhaps the most extreme published claim, ridiculed by Ellis (1998a:142), appeared in
Willy Ley Willy or Willie is a masculine, male given name, often a diminutive form of William or Wilhelm, and occasionally a nickname. It may refer to: People Given name or nickname * Willie Aames (born 1960), American actor, television director, and scr ...
's 1959 book, '' Exotic Zoology'': "Toothed whales, vomiting in death struggle, have shown evidence of still larger kraken; in one case a 6-foot [] piece of tentacle, ''with a diameter of 2 feet'' [; emphasis in original], has been claimed. Another claim goes for marks on the skin of such a whale, looking like the mark of a sucking disk over 2 feet [] in diameter". Marine biologist Frederick Aldrich, who personally examined more than a dozen giant squid specimens, wrote that his largest specimen from Newfoundland bore tentacular suckers "approximately two inches [] in diameter" but that "[s]uckers and their toothed armament of over twelve inches [] in diameter have been found in the stomachs of sperm whale as indigestible wastes".#Aldrich1980, Aldrich, 1980:59 This led him to entertain the idea of giant squid over long, and even to suggest a binomial name for this super-sized species, were it ever to be discovered: ''Architeuthis halpertius''. By comparison, giant squid suckers ''normally'' reach a maximum diameter of only a few centimetres. Based on a detailed examination of a number of large specimens from New Zealand waters, Förch (1998:55) wrote that " e largest suckers ..on the sessile arms are a very constant in external diameter". In giant squid the largest suckers of all are found on the central portion of the
tentacular club All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles. Description In the scientific l ...
, called the '' manus'', and among the specimens examined by Förch (1998:53) these reached a maximum diameter of . Clarke (1980) wrote: "I have not yet seen conclusive evidence to suggest that sucker scars are larger than across". According to Roper & Boss (1982:97), the largest suckers of the tentacular clubs reach in diameter.


=Mass estimates

= It is now accepted that the giant squid has a maximum mass of several hundred kilograms, but the literature is rife with claims of much greater weights. Clarke (1966), for example, put the mass of the largest giant squid specimens at around . Similarly, Richard Ellis wrote: "Where iantsquid carcasses have actually been weighed, it appears that the longest ones—in the 50-foot [] range, for example—weigh about a ton []."#Ellis1998a, Ellis, 1998a:106 Much greater estimates of giant squid mass can be found in, for example, ''Natural History of Marine Animals'' by MacGinitie & MacGinitie (1949): "two arms of ''Architeuthis'' that were long were found, and if one reconstructed a body ..the squid to which these arms belonged was in diameter and long, with an overall measurement of . It would have weighed about 42 tons []." They added that a specimen, such as the one reported from Thimble Tickle, "would have weighed 29 or 30 tons [] including the tentacles—a truly noble animal, being a little more than one-fifth the weight of the blue whale, largest whale and larger than the whale sharks and basking sharks, the largest of all fishes". Ellis characterised these estimates as "unfounded exaggerations". In the revised edition of ''Natural History of Marine Animals'', published in 1968, the authors reduced their estimate to less than 8 tonnes.
Bernard Heuvelmans Bernard Heuvelmans (10 October 1916 – 22 August 2001) was a Belgian-French scientist, explorer, researcher, and writer probably best known, along with Scottish-American biologist Ivan T. Sanderson, as a founding figure in the pseudoscienc ...
believed that "there must be ''Architeuthis'' weighing more than 5 tons, and some even larger ones which must weigh between 2 and 27 tons, the normal weight being around 8 tons. There are good reasons to believe that there may even exist specimens twice as long as that of Thimble Tickle, which, depending upon their girth, might have weighed between 16 and 216 tons, but more likely around 64 tons." Ellis, who considered these estimates "utterly ridiculous", wrote:
Heuvelmans commits a fundamental error in calculating the weight of some of these monsters when he writes that "the density of living creatures is only slightly higher than that of water ... a decimetre of living flesh weighs about as much as a litre of water." That may be true for some other living creatures, but the flesh of ''Architeuthis'', saturated with ammonium chloride, is ''lighter'' than water, and the giant squid is neutrally buoyant. (This is believed to be the reason that dead or dying squid are found floating at the surface or washed up on the beach.) His assumption, therefore, that the 55-foot-long [] Thimble Tickle squid would have "probably weighed near 24 tons" is patently erroneous.
On the subject of the Thimble Tickle specimen's mass, #Wood1982, Wood (1982:190) referred to the work of
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...
zoologist and writer Igor Akimushkin:
According to Dr Igor Akimushkin (1965), the Russian teuthologist, a long giant squid will weigh 1 tonne [] if the head, mantle and arms combined make up half the total length. Since there is a Cube (algebra), cubic relationship between the linear dimensions of ''Architeuthis'' and its volume or weight, this means the Thimble Tickle monster must have scaled about 2.8 tonnes [] (i.e. the weight of a large bull hippopotamus), although 2 tonnes [] is probably a more realistic figure.


Giant Pacific octopus

The maximum size of the
giant Pacific octopus The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus ''Enteroctopus''. Its spatial distribution includes the coastal North Pacific, along Mexico ...
(''Enteroctopus dofleini'') has long been a source of debate in the scientific community, with dubious reports of specimens weighing hundreds of kilograms.


=Largest reported animals

= In 1885, reporting on the longest octopus specimen reliably recorded up to that point, renowned
malacologist Malacology is the branch of invertebrate zoology that deals with the study of the Mollusca (mollusks or molluscs), the second-largest phylum of animals in terms of described species after the arthropods. Mollusks include snails and slugs, clams, ...
William Healey Dall William Healey Dall (August 21, 1845 – March 27, 1927) was an American naturalist, a prominent malacologist, and one of the earliest scientific explorers of interior Alaska. He described many mollusks of the Pacific Northwest of America, and ...
wrote:
In 1874 I speared an octopus in the harbor of Iliuliuk, Unalashka, which was afterward hung, by a cord tied around the body immediately behind the arms, to one of the stern davits of the coast survey vessel under my command. As soon as the animal died and the muscles relaxed, I noticed that the tips of the longer tentacles just touched the water. On measuring the distance with a cord, I found it to be sixteen feet [], giving the creature a spread from tip to tip of the longest pair of arms, of not less than thirty-two feet []. The arms toward the tips were all exceedingly slender, but rather stout toward the body, which was somewhat over a foot [] long. The largest suckers were two and a half inches [] in diameter; the whole creature nearly filled a large washtub. Parts of this specimen are now in the National Museum of Natural History, U. S. national museum.
In an article for the
National Marine Fisheries Service The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the ste ...
summarising knowledge on the giant Pacific octopus, High (1976:17–18) wrote:
Several octopuses in excess of 100 pounds [] have been encountered and captured. Much larger ones have been reported but, like the Loch Ness Monster, these usually elude the careful photographer or scientist. Most octopuses weigh less than 70 pounds [] with a stretched length of 15 feet [] or less. Overall length between arms is not a suitable measure because of the animal's unusual elasticity. In the late 1950s, I interviewed a Canadian commercial diver, Jock MacLean of Prince Rupert, B.C. He reported capturing an immense creature weighing 600 pounds [] and measuring 32 feet [] from arm tip to top. MacLean's photographs, unfortunately, were of poor quality. Smaller animals, to 400 pounds [], were occasionally taken in his commercial octopus fishing endeavor.
Hochberg & Fields (1980:436) referenced the same specimen, writing: "the largest specimen on record with a total arm spread of 9.6 m [] and a weight of 272 kg []". These figures are only estimates, however, as—contrary to the above quotation from High (1976:17–18)—it appears that this specimen was never collected and measured. Murray Newman, director of the
Vancouver Aquarium The Vancouver Aquarium is a public aquarium located in Stanley Park in Vancouver, British Columbia, Canada. In addition to being a major tourist attraction for Vancouver, the aquarium is a centre for marine research, ocean literacy education, cl ...
for 37 years, quoted Jock MacLean in his 1994 memoir, ''Life in a Fishbowl'': "Next year 957in the same place, I saw one, maybe thirty-two feet [] across and six hundred pounds []. Didn't go for her, though, no place to keep her!" Nevertheless, the false precision, misleadingly precise metric system, metric Conversion of units, conversion of 272 kg (for 600 lb) and the ''im''precise conversion of 9.6 m (for 32 ft; naively employing a conversion factor of 0.3 instead of 0.3048) gained wide acceptance as the maximum recorded dimensions of the giant Pacific octopus, and have been much repeated. Jock MacLean is also reported to have ''captured'' a animal with an arm span of near
Port Hardy Port Hardy is a district municipality in British Columbia, Canada located on the north-east end of Vancouver Island. Port Hardy has a population of 4,132 as of the last census (2016). It is the gateway to Cape Scott Provincial Park, the North ...
,
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, in March 1956. Another giant specimen was caught off Santa Barbara,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, in 1945. Its weight was recorded as and the surviving photograph makes it possible to estimate its total length at more than and arm span at . In a book dedicated to the giant Pacific octopus, Cosgrove & McDaniel (2009:72) summarised knowledge on the species's maximum size as follows:
The specimen William Dall speared in 1885 at Iliuliuk had the largest radial span of any giant Pacific octopus ever measured. Jock MacLean's 1956 Port Hardy behemoth was the biggest ever weighed. The Santa Barbara specimen photographed in 1945 was the second heaviest. It would appear that octopuses weighing as much as and with radial spans of over are within the realm of possibility, but have never actually been documented by both measuring and weighing.


=Possible diminution in size

= No specimens approaching these extreme sizes have been reported since the middle of the 20th century. This lack of giant individuals is corroborated by commercial octopus fishers; none of those interviewed by Cosgrove & McDaniel (2009) had caught a single animal weighing more than in the previous 20 years, among many thousands harvested over that period. Octopus specialist Roland Anderson, a biologist with the
Seattle Aquarium The Seattle Aquarium is a public aquarium in Seattle, Washington, United States, located on Pier 59 on the Elliott Bay waterfront. It opened in 1977 and has been accredited by the Association of Zoos and Aquariums (AZA). History Plans for a ci ...
for more than 30 years, had long sought, unsuccessfully, to find a giant Pacific octopus weighing more than . In an attempt to raise a truly enormous specimen, Anderson fed a number of captive males ''
ad libitum In music and other performing arts, the phrase (; from Latin for 'at one's pleasure' or 'as you desire'), often shortened to "ad lib" (as an adjective or adverb) or "ad-lib" (as a verb or noun), refers to various forms of improvisation. The ...
''. The heaviest animal (nicknamed 'Big') attained a peak weight of and its largest suckers measured in diameter. Anderson suggested the species might now be maturing at a smaller size as a result of
toxicant A toxicant is any toxic substance, whether man-made or naturally occurring. By contrast, a toxin is a poison produced naturally by an organism (e.g. plant, animal, insect). The different types of toxicants can be found in the air, soil, water, or ...
bioaccumulation, which could explain the lack of truly gigantic specimens in recent times. In particular, high concentrations of heavy metals and
PCBs Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...
have been identified in the
digestive gland The hepatopancreas, digestive gland or midgut gland is an organ of the digestive tract of arthropods and molluscs. It provides the functions which in mammals are provided separately by the liver and pancreas, including the production of digestive e ...
s of wild giant Pacific octopuses, likely originating from their preferred prey, the red rock crab (''Cancer productus''). A preliminary study found that aquarium animals fed equal quantities of raw sea food and live ''C. productus'' (caught locally in
Elliott Bay Elliott Bay is a part of the Central Basin region of Puget Sound. It is in the U.S. state of Washington, extending southeastward between West Point in the north and Alki Point in the south. Seattle was founded on this body of water in the 1850s ...
) matured at a smaller size, reached a lower maximum weight ( mean), and had higher concentrations of most heavy metals, than those fed solely on raw sea food ( mean, including the aforementioned specimen).


Largest species by measure

Cephalopod size can be quantified in various ways. Some of the most common size measures are covered below. The following four tables list only extant species; extinct taxa are treated separately at the end.


Mantle length

The list of largest cephalopods by mantle length is dominated by squids, with more than twenty species exceeding the largest-bodied octopuses and cuttlefish. The largest of all is the
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
(''Mesonychoteuthis hamiltoni'') with an estimated maximum mantle length of ( Roper & Jereb, 2010c:173). Even greater mantle lengths have historically been reported for the
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
(''Architeuthis dux''), but these have been discredited (see O'Shea & Bolstad, 2008).


Total length

The longest scientifically documented specimens belong to the
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
, with a maximum total length of ( Roper & Shea, 2013:114). Despite its proportionally shorter tentacles, the
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
may rival the giant squid in total length, but the species's size limits are uncertain because only a handful of mature specimens have been recorded.


Mass

The heaviest known cephalopod, and the largest living invertebrate, is the
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
. The largest recorded specimen of this species, caught in the
Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who ...
in 2007, weighed . However, its beak is not the largest known from this species; even bigger colossal squid beaks have been recovered from the stomachs of sperm whales, indicating that this species can grow larger still.


Shell diameter

Nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in ...
es are the only extant cephalopods with a true external shell; in other groups the shell has been internalised or lost completely. Internal shells include the
cuttlebone Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all members of the family Sepiidae, commonly known as cuttlefish, within the cephalopods. In other cephalopod families it is calle ...
s of cuttlefish, the gladii of squids and the vampire squid, the winged shells of cirrate octopods, and the spiral shells of ''
Spirula ''Spirula spirula'' is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus ''Spirula'', the family Spirulidae, and the order Spirulida. Because of the shape of its internal shell, it is commonly known ...
''. Additionally, females of the octopus genus '' Argonauta'' secrete a specialised paper-thin eggcase in which they reside, and this is popularly regarded as a "shell", although it is not attached to the body of the animal (see Finn, 2013). Cephalopod shell diameter is of interest to
teuthologist Teuthology (from Greek , " cuttlefish, squid", and , ''-logia'') is the study of cephalopods such as octopus, squid, and cuttlefish.
s and conchologists alike. The '' Registry of World Record Size Shells'', the most comprehensive publication on maximum shell size in marine molluscs, specifies that specimens "should be measured with vernier type calipers and should reflect the greatest measurable dimension of the shell in any direction including any processes of hard shell material produced by the animal (i.e. spines, wings, keels, siphonal canals, etc.) and not including attachments, barnacles,
coralline algae Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of ...
, or any other encrusting organisms" ( Pisor, 2008:14). Unlike most other measures of cephalopod size, shell diameter can be determined with a high degree of precision and usually leaves little room for ambiguity. For this reason it is usually recorded to the nearest one-tenth of a millimetre (), as is standard in
conchology Conchology () is the study of mollusc shells. Conchology is one aspect of malacology, the study of molluscs; however, malacology is the study of molluscs as whole organisms, whereas conchology is confined to the study of their shells. It includ ...
. When the '' Registry of World Record Size Shells'' changed ownership in 2008 it was launched as an online database in addition to its print publication. Subsequent rule changes meant that all records required photographic verification. Over time, older records for which photographic evidence could not be obtained were removed from the database. As a result, some records from older editions of the registry actually exceed the size of the current official record holders, sometimes by considerable margins. Where this has occurred, the largest recorded size across all editions is shown first and any discrepancies or competing records are noted thereafter. Where a reliable literature record surpasses all specimens ever included in the registry, this is given instead and the registry record(s) noted thereafter. Pisor (2008) was the fifth and final print edition of the registry published prior to the rule change, and Barbier ''et al.'' () is the current, continuously updated online database. The registry only covers the shells of
nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in ...
es and ''
Spirula ''Spirula spirula'' is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus ''Spirula'', the family Spirulidae, and the order Spirulida. Because of the shape of its internal shell, it is commonly known ...
'' and the eggcases of '' Argonauta''.


Extinct taxa


Anatomical superlatives


Eyes

The
giant In folklore, giants (from Ancient Greek: ''gigas'', cognate giga-) are beings of human-like appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''giant'' is first attested in 1297 fr ...
and
colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized ...
s have the largest recorded
eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...
of any living animal, with a maximum diameter of at least and a
pupil The pupil is a black hole located in the center of the Iris (anatomy), iris of the Human eye, eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing ...
. This is three times the size of the largest
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
eyes—up to in swordfish—and more than twice the diameter of the largest
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
eyes—up to , , and in
blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when ...
, humpback, and sperm whales, respectively—which are the largest among
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
s. A large colossal squid caught in 2014 and dissected at the Museum of New Zealand Te Papa Tongarewa had eyes some across. There are unconfirmed reports from the 19th century of giant squid eyes up to across. Only the extinct ichthyosaurs are known to have approached these dimensions, with some species having eyes up to in diameter. Despite their size, the eyes of giant and colossal squids do not appear to be disproportionately large; they do not deviate significantly from the allometric relationship seen across other squid species. Sepiolids are noted for having exceptionally large eyes, which are much bigger relative to their mantle length than those of the giant squid; the same is true of '' Histioteuthis'' species. Gonatids and the loliginids ''
Loligo ''Loligo'' is a genus of squid and one of the most representative and widely distributed groups of myopsid squid. The genus was first described by Jean Baptiste Lamarck in 1798. However, the name had been used earlier than Lamarck (Schneider, ...
'' and ''
Lolliguncula ''Lolliguncula'' is a genus of squid from the family Loliginidae from the eastern Pacific and western Atlantic, known as brief squid. The genus is divided into two subgenera ''Lolliguncula'' and ''Loliolopsis''. They are rather small squids with ...
'' also have proportionately somewhat larger eyes than ''Architeuthis''. Some sources state that the
vampire squid The vampire squid (''Vampyroteuthis infernalis'', lit. 'vampire squid from hell') is a small cephalopod found throughout temperate and tropical oceans in #Habitat and adaptations, extreme deep sea conditions. The vampire squid uses its Biolumines ...
(''Vampyroteuthis infernalis'') has the largest eyes of any animal relative to its size, with a specimen having eyes around in diameter. There is some debate in the scientific community as to the evolutionary reason behind the extremely large eyes of giant and colossal squids. Nilsson ''et al.'' (2012) and Nilsson ''et al.'' (2013) argue that it is an
anti-predator adaptation Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...
for enhanced detection of sperm whales, with the squids picking up
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
bioluminescence triggered by moving whales, perhaps from distances exceeding . Schmitz ''et al.'' (2013a) and Schmitz ''et al.'' (2013b) contend that their eyes are so large due to a phylogenetically conserved developmental pattern that governs the relative dimensions of squids and their eyes, and that any fitness benefits their size may confer in terms of predator avoidance are the result of exaptation ("pre-adaptation").


Neurons

Squid giant axon The squid giant axon is the very large (up to 1.5 mm in diameter; typically around 0.5 mm) axon that controls part of the water jet propulsion system in squid. It was first described by L. W. Williams in 1909, but this discovery was fo ...
s can exceed in diameter: 100 to 1000 times the thickness of mammalian
axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action p ...
s. The axons of the
Humboldt squid The Humboldt squid (''Dosidicus gigas''), also known as jumbo squid or jumbo flying squid (EN), and Pota in Peru or Jibia in Chile (ES) is a large, predatory squid living in the eastern Pacific Ocean. It is the only known species of the genus ''D ...
(''Dosidicus gigas'') are exceptional in that they can reach a diameter of as much as , and those of ''
Loligo forbesii ''Loligo forbesii'' (sometimes erroneouslyBouchet, P. and S. Gofas. (2013)''Loligo forbesi'' Steenstrup, 1856.World Register of Marine Species. Accessed 5 June 2013. spelled ''forbesi''), known commonly as the veined squid and long-finned squid, ...
'' can also exceed 1 mm. Adelman & Gilbert, 1990:102 Such was the importance of Humboldt squid to
electrophysiology Electrophysiology (from Ancient Greek, Greek , ''ēlektron'', "amber" ee the Electron#Etymology, etymology of "electron" , ''physis'', "nature, origin"; and , ''-logy, -logia'') is the branch of physiology that studies the electrical propertie ...
research that when the animals migrated out of reach of
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
an fishermen in the 1970s "it led to the demise of a world-class electrophysiology laboratory" based there. Squid giant axon diameters do not necessarily correlate with overall body size; those of the
giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around Trac ...
(''Architeuthis dux'') are only thick. The
squid giant synapse The squid giant synapse is a chemical synapse found in squid. It is the largest chemical junction in nature. Anatomy The squid giant synapse (Fig 1) was first recognized by John Zachary Young in 1939. It lies in the stellate ganglion on each s ...
is the largest chemical junction in nature. It lies in the stellate ganglion on each side of the midline, at the posterior wall of the squid's muscular mantle. Activation of this synapse triggers a synchronous contraction of the mantle musculature, causing the forceful ejection of a jet of water from the mantle. This water propulsion allows the squid to move rapidly through the water and, in the case of the so-called 'flying squids', even to jump through the surface of the water (breaking the air–water barrier) to escape predators. Many essential elements of how all chemical synapses function were first discovered by studying the squid giant synapse.


Photophores

'' Taningia danae'', a very large octopoteuthid squid, possesses "lemon-sized" yellow
photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...
s at the tips of two of its
arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...
, which are the largest known light-emitting organs in the animal kingdom. Video footage shot in 2005 in deep water off Japan shows ''T. danae'' emitting blinding flashes of light from these photophores as it attacks its prey. A pair of muscular lids surrounds each photophore and it is the withdrawal of these lids that produces the flashes. A large individual filmed from a remote submersible off
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
in 2015 can clearly be seen opening the lids to reveal its photophores. It is believed that this highly manoeuvrable squid uses bright flashes to disorientate potential prey. The flashes may also serve to illuminate prey for easier capture or play a role in courtship and/or territorial displays.


Reproductive organs

Extreme penis elongation has been observed in the deep water squid '' Onykia ingens''. When erect, the penis may be as long as the mantle, head, and arms combined. As such, deep water squids have the greatest known penis length relative to body size of all mobile animals, second in the entire animal kingdom only to certain sessile barnacles. Arkhipkin & Laptikhovsky, 2010:300


See also

* Deep-sea gigantism *
Gigantic octopus The kraken () is a legendary sea monster of enormous size said to appear off the coasts of Norway. Kraken, the subject of sailors' superstitions and mythos, was first described in the modern age at the turn of the 18th century, in a travelog ...
* Largest body parts *
Largest organisms 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 ...
* Largest prehistoric organisms *
Smallest organisms The smallest organisms found on Earth can be determined according to various aspects of organism size, including volume, mass, height, length, or genome size. Given the incomplete nature of scientific knowledge, it is possible that the small ...


Notes


References


Short citations


Full citations

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External links


How big is the colossal squid?
Museum of New Zealand Te Papa Tongarewa
How big are the biggest squids?
Discovery Channel
World's Largest Squid
New Zealand Ministry of Fisheries
How Big Is A Colossal Squid Really?
an
Whale Sharks and Giant Squids: Big or Bu!!$hit?
— Deep Sea News
Accurately measured lengths of ''Architeuthis dux''
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Giant Cephalopods
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{{Col-end Animal size Biological records Giant squid
Size Size in general is the magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to linear dimensions ( length, width, height, diameter, perimeter), area, or volume. Size can also be m ...