Cephalopod size

Source: Wikipedia, the free encyclopedia.
The giant squid (Architeuthis dux, pictured) was for a long time thought to be the largest extant cephalopod. It is now known that the colossal squid (Mesonychoteuthis hamiltoni) attains an even greater maximum size. The giant squid seen here measured 9.24 m (30.3 ft) in total length and had a mantle length of 1.79 m (5.9 ft).

orders of magnitude, from the lightest hatchlings to the heaviest adults.[4] Certain cephalopod species are also noted for having individual body parts of exceptional size.[5]

Cephalopods were at one time the

endocerid nautiloids,[7] though perhaps still second to the largest living cephalopods when considering tissue mass alone.[8]

Cephalopods vastly larger than either giant or colossal squids have been postulated at various times. One of these was the St. Augustine Monster, a large carcass weighing several tonnes that washed ashore on the United States coast near St. Augustine, Florida, in 1896. 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.[9]

Giant cephalopods have fascinated humankind for ages. The earliest surviving records are perhaps those of

Nordic legend, said to be as large as an island and capable of engulfing and sinking any ship.[11] Similar tentacled sea monsters are known from other parts of the globe, including the Akkorokamui of Japan and Te Wheke-a-Muturangi of New Zealand. The Lusca of the Caribbean and Scylla in Greek mythology may also derive from giant squid sightings,[12] as might eyewitness accounts of other sea monsters such as sea serpents.[13]

Cephalopods of enormous size

.

Due to its status as a charismatic megafaunal species, the giant squid has been proposed as an emblematic animal for marine invertebrate conservation.[15] Life-sized models of the giant squid are a common sight in natural history museums around the world,[16] and preserved specimens are much sought after for display.[17]

Size in teuthology

Standard measurements for cephalopods with a squid and octopus as examples

Mantle length

Scientists measuring the mantle width of a large female giant squid of c. 2 m (6.6 ft) ML

Mantle length (ML) is the standard size measure for

dorsally 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 (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, whichever is longer. In Octopodiformes (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.[18]

As an indication of overall size, mantle length is generally considered more reliable than total length because

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.[20]

Total length

Total length (TL) is measured along the

tail, if present[21]) to the apex of the longest limb.[18] 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 measurements have been attributed to artificial lengthening of the tentacles.[22] Although total length is often mentioned in relation to the largest cephalopod species, it is otherwise seldom used in teuthology.[23]
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.[24] 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).

Giant squid beak and associated muscles with hand for scale

Methods of size determination

In contrast to the vast majority of living cephalopods, which are wholly soft-bodied, size determination of the

hood length is preferred for Octopodiformes.[26]

Mantle length has been estimated from video recordings of squid in the wild.[27]


Early life stages

Hatchlings

Cape Verde Islands
. The eggs measure around 8 mm (0.31 in) across the long axis.

Hatchlings of Idiosepius thailandicus, possibly the smallest extant cephalopod species at maturity, have a mantle length of around 1 mm (0.039 in).[28] The closely related Idiosepius pygmaeus weighs only 0.00033 g (1.2×10−5 oz) upon hatching and increases in weight to 0.175 g (0.0062 oz) as it reaches maturity in 50 days.[2] Even smaller are the hatchlings of the commercially important Illex illecebrosus, with a mass of 0.00015 g (5.3×10−6 oz).[29] Hatchlings of the giant Pacific octopus (Enteroctopus dofleini)—one of the two largest octopus species—weigh 0.0253 g (0.00089 oz) on average.[30]

At the other extreme are nautiluses, which upon hatching typically have a shell diameter of 25 mm (1 in) or more (depending on the species), the largest hatchling size among extant invertebrates.[31] Hatchlings of Nautilus belauensis, one of the larger species, are estimated to weigh on the order of 5.9 g (0.21 oz)[nb 2] and mature at around 1.2 kg (2.6 lb) after almost 4000 days, or around 11 years.[2]

Idiosepius paradoxus, a tiny species of squid that grows to 16 mm (0.63 in) in mantle length

Smallest adult size

The smallest adult size among living cephalopods is attained by the so-called pygmy squids, Idiosepius,[32] and certain diminutive species of the genus Octopus, both of which weigh less than 1 gram (0.035 oz) at maturity.[33] Idiosepius thailandicus is perhaps the smallest of all, with females averaging 10.4 mm (0.41 in) in mantle length and males 5.9 mm (0.23 in).[3] Average wet weights are around 0.20 and 0.02 g (0.00705 and 0.00071 oz), respectively.[3]

Other tiny species include members of the

Spirula spirula
.

Male dwarfism

Tremoctopus violaceus with large hectocotylus (arm modified for spermatophore
transfer)

The octopod superfamily

sexual size dimorphism known among non-microscopic animals,[nb 3] with mature females being at least 10,000 times heavier than males, and likely up to 40,000 times heavier.[35] 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 up to length of 3.5 m (11 ft) and mass of 75 kg (165 lb) (and possibly the largest octopuses of any kind), but the males are also much larger, at up to 30 cm (12 in). So, the size dimorphism is least pronounced of all.[36]

Extinct taxa

Numerous species of so-called micromorphic ammonites are known.

Upper Carboniferous is the smallest known ammonoid. Adult specimens reached only 10 mm (0.39 in) in shell diameter.[38]

Maximum size

Scientifically validated records

The largest cephalopod specimen ever recorded: a 495 kg (1,091 lb) colossal squid

Haliphron atlanticus—can both exceed 70 kg (150 lb), and the former has a maximum total length of more than 6 m (20 ft). Cirrate (finned) octopods can also reach a large size, with the largest captured specimen likely being a Cirrothauma magna of 1.7 m (5.6 ft) total length and 33 cm (13 in) mantle length,[41] though observations from submersibles suggest that members of this group can exceed 4 m (13 ft) in total length.[42]

Members of the other cephalopod groups are substantially smaller, although the largest

Colossal squid (Mesonychoteuthis hamiltoni)

Beak of a colossal squid, which has the largest beak among living cephalopods

Though a substantial number of colossal squid (Mesonychoteuthis hamiltoni) remains 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

formalin and later propylene glycol).[46] The fins of the 2007 Ross Sea specimen measured around 1.2 m (3.9 ft) across and it had a mantle width of 98.2 cm (3.22 ft).[47] The arms ranged in length from 0.85 to 1.15 m (2.8 to 3.8 ft), while the two tentacles were around 2.1 m (6.9 ft) long.[48]

Museum of New Zealand Te Papa Tongarewa

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 42.5 mm (1.67 in) and weighed 495 kg (1,091 lb),[49] where as the 300 kg (660 lb) submature female from 2003 had a LRL of 37 mm (1.5 in).[50] By comparison, the largest known colossal squid beak from a sperm whale stomach measured 49 mm (1.9 in) in LRL.[22] 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 600–700 kg (1,300–1,500 lb).[49] However, the scaling relationship for this species shows considerable latitude, as demonstrated by a beak of 40 mm (1.6 in) LRL extracted from an animal weighing only 160 kg (350 lb).[49]

Giant squid (Architeuthis dux)

A giant squid specimen; the extremely long feeding tentacles of the giant squid make it the longest known cephalopod, past or present.

The maximum size of the giant squid (Architeuthis dux) has long been a subject of both popular debate and academic inquiry.[51] 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 as of 2015, of which around 460 had been measured in some way.[52] This number has since increased substantially, with 57 specimens recorded from Japanese waters during an exceptional 15-month period between 2014 and 2015.[53]

Melbourne Aquarium[54]

Based on a 40-year data set of more than 50 giant squid specimens,

upper bound he would consider plausible for the giant squid's total length would be 15 m (49 ft), 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".[58]

Including the head and arms but excluding the tentacles (standard length, SL), the species very rarely exceeds 5 m (16 ft) according to O'Shea & Bolstad (2008). Paxton (2016a) considers 9.45 m (31.0 ft) to be the greatest reliably measured SL, based on a specimen reported by Verrill (1880a:192), and considers specimens of 10 m (33 ft) SL or more to be "very probable", but these conclusions have been criticised by giant squid experts.[59] O'Shea (2003a) put the maximum weight of female giant squid at 275 kg (606 lb), 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 150 kg (330 lb),[56] though heavier specimens have occasionally been reported (such as a 190 kg (420 lb) specimen[60] and a 163 kg (359 lb) specimen[61]). Roper & Jereb (2010a:121) give a maximum weight of up to 500 kg (1,100 lb), and "possibly greater". Discredited weights of as much as a tonne (2,200 lb) or more are not uncommon in older literature (see below).[22]

Other squid taxa

Dana octopus squid

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 61.4 kg (135 lb), but according to Roper & Jereb (2010h:266) this figure is wrong and stems from a typographical error, the correct mass being 161.4 kg (356 lb). Roper & Vecchione (1993) were however consistent in their use of the 61.4 kg figure. Another similarly large specimen—a female weighing 124 kg (273 lb)—was reported from northern Spanish waters by González et al. (2003:297) (see also initial reports[62]). 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 1.5–2 m (4.9–6.6 ft); this would approximate its mantle length.[63]

Onykia robusta grows to a mantle length of at least 2 m (6.6 ft)

Onykia robusta, previously known as Moroteuthis robusta[64] and sometimes called the robust clubhook squid, has a mantle length of up to 200 cm (6.6 ft).[65] Some older records exceed this, such as the 91.5 in (232 cm) ML reported by Verrill (1876:237) from a specimen with a total length of 14 ft (4.3 m) (excluding the ends of the tentacles, which had been destroyed). Nesis (1987:192) likewise gave a maximum mantle length of 230 cm (7.5 ft), but Roper & Jereb (2010i:364) wrote that "this old record might be in error", with the species commonly growing to 160 cm (5.2 ft) ML. Glaubrecht & Salcedo-Vargas (2004:66) provided a maximum total length of 4–6 m (13–20 ft). Literature sources give a maximum weight of 50 kg (110 lb).[66] There exist numerous published records of large individuals of this species.[67]

Fisherman taking a Humboldt squid off the coast of Chile. This species is the largest squid commonly encountered by humans.[68]

The

northern hemisphere are much smaller, with those off the Californian coast reaching total lengths of less than 1.7 m (5.6 ft).[73] The Humboldt squid commonly attains a weight of around 20–30 kg (44–66 lb)[71] and can reach a maximum of 50 kg (110 lb).[74] 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).[75][nb 4]

Kondakovia longimana, sometimes known as the giant warty squid, is a little known species with a circum-Antarctic distribution in the Southern Ocean. The largest complete specimen, found floating at the surface off the South Orkney Islands, had a mantle length of 108 cm (3.54 ft),[76] but a damaged female specimen with an estimated mantle length of around 150 cm (4.9 ft) is known.[77] The largest complete specimen had a wet weight of 29 kg (64 lb).[76] The species' maximum weight has been estimated at 50 kg (110 lb).[78]

Largest octopodes

The giant Pacific octopus is one of the two largest octopus species

The giant Pacific octopus (Enteroctopus dofleini) grows to more than 6.1 m (20 ft) in total length[79] and at least 60 cm (2.0 ft) in mantle length.[80] Cosgrove (1987) and Cosgrove & McDaniel (2009:69) gave a maximum confirmed weight of 71 kg (157 lb) for a live specimen collected in the mid-1960s.[40] Norman et al. (2014:124) accept a maximum weight of at least 180 kg (400 lb), which approximates the 182.3 kg (402 lb) reported for a specimen caught off Santa Barbara, California, in 1945, of which photographic evidence survives.[81] No specimens approaching this size have been reported since the middle of the 20th century, with recent specimens very rarely exceeding 50 kg (110 lb).[82] It is possible that the maximum size of the species has decreased over this period, perhaps due to bioaccumulation of toxicants (see below).[83]

In 2002, a giant specimen of

South Pacific. It had a mantle length of 0.69 m (2.3 ft), a total length of 2.90 m (9.5 ft), and a weight of 61.0 kg (134.5 lb), although it was incomplete.[84] The total length of the specimen, when complete, has been estimated at 4 m (13 ft), and its weight at 75 kg (165 lb).[85]

Extinct taxa

The largest known specimen of Parapuzosia seppenradensis, with its describing author, Hermann Landois, who reconstructed its missing living chamber with a combination of wire frame and paper.[86] Landois assumed that the living chamber constituted one-fourth of the outer whorl, but Teichert & Kummel (1960:6) estimated that it continued for three-fourths to one full whorl, which would give an original shell diameter of around 3.5 m (11 ft).

Certain extinct cephalopods rivalled or even exceeded the size of the largest living species.

living chamber is largely missing. The diameter of the complete shell has been estimated at 2.55 m (8.4 ft), assuming the living chamber took up one-fourth of the outer whorl.[89] Teichert & Kummel (1960:6) suggested an even larger original shell diameter of around 3.5 m (11 ft) 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 in Bottrop, western Germany.[90] A specimen found by Jim Rockwood, from the Late Triassic near Williston Lake, British Columbia, was said to measure more than 8 ft (2.4 m) across, but was later determined to be a concretion.[91]

Dosidicus

Middle Ordovician limestone of Estonia[92] and Frey (1995:72) gave a maximum shell length of 6 m (20 ft) 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 [3.7 m] 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, which was measured before it was broken up and found to attain a length of 30 feet [9.1 m].[93]

However, the uncoiled length of the largest ammonites far exceeds that of even these giant endocerids.

body chamber, which occupies only a fraction of the internal shell volume.[8] They might also be the largest—or at least longest—shell-bearing animals that have ever lived.[8][nb 5]

Cretaceous Yezo Group in Japan yields multiple taxa of large-sized cephalopod fossil remains. Oegopsid Yezoteuthis giganteus and Haboroteuthis poseidon are only known from jaw elements, which is close to size of that of giant squid. Species of Nanaimoteuthis, especially N. hikidai would be the largest known vampyromorph.[96] Unnamed, incomplete upper jaw fossil that is approximately twice as large as that of the mature giant squid is also found there.[97]

Historical claims

Misidentifications

Kubota's photograph of a large Onykia robusta, which was misidentified as the giant squid, Architeuthis dux. Wide-angle photography exaggerated the size of the squid[98] such that it appeared impossibly large for the species.

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

Psychroteuthidae.[99][nb 6] This situation is further confused by the occasional usage of the common name 'giant squid' in reference to large squids of other genera.[100]

Perhaps the most notable misidentification relates to a photograph taken some time before 1993 by diver H. Kubota off southern

North Atlantic.[102] If true, this image would represent the first known photograph of a live giant squid. In The Search for the Giant Squid (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.[98]

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 and Kyoichi Mori.[103] Kubodera and his team subsequently became the first to film a live adult giant squid on 4 December 2006,[104] and the first to film a live giant squid in its natural habitat in July 2012.[105] These milestones were preceded by the first footage of a live (paralarval) giant squid in 2001,[106] and the first image of a live adult giant squid on 15 January 2002.[107] Since then, live giant squid have been photographed and filmed on a number of occasions.[108]

Giant squid

Newfoundland, on 24 September 1877. A number of exceptionally large giant squid were reported from Newfoundland in the 1870s, and these were meticulously documented in a series of papers by zoologist Addison Emery Verrill.[109]

Reports of giant squid (Architeuthis dux) specimens reaching or even exceeding 18 m (59 ft) in total length are widespread, but no animals approaching this size have been scientifically documented in recent times.[110] This is despite there being hundreds of specimens available for study (c. 700 documented as of 2015, of which c. 460 measured in some way[52]), including numerous recent examples, such as the 57 specimens recorded from Japanese waters over a 15-month period in 2014–2015.[53] 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.[57]

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:

If this figure [45 ft or 14 m] seems a little short of the

Brobdingnagian claims made for Architeuthis in most pop-science
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.[nb 7] 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 [14 m] total length. Most are in the 25–35-foot [7.6–10.7 m] 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
Architeuthis dux. The 2,000 lb (910 kg) extreme outlier is sourced from Verrill (1880a) and is unlikely to be accurate; the next most massive individual in the data set was only 700 lb (320 kg), and 95% of specimens were below 250 kg (550 lb).[40]
Log–log linear regressions for Architeuthis dux: (A) total length vs. mass; (B) mantle length vs. total length; and (C) mantle length vs. mass[40]

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.[59]

For mantle length,

North Atlantic off Portugal, attributed to a personal communication with T. Lipington. A more modest 4 m (13 ft) ML is also given, based on a sighting in the Indian Ocean sourced to the TV documentary of Lynch (2013)
.

For standard length (excluding the tentacles), Paxton (2016a:83) cited the 31 ft (9.45 m) 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 16 ft 3 in (4.95 m) reported by Clarke (1956:257) and the longest "visually estimated" SL is the c. 9 m (30 ft) attributed to a photograph of a sperm whale with giant squid remains in its jaws,[111] though Paxton conceded that it is "[n]ot clear how much/what portion of body was eaten". For the "longest visually estimated", more extreme supposed SLs of c. 175 ft (53 m) and c. 100 ft (30 m) 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,

Thimble Tickle specimen" reported by Verrill (1880a:191), which is often cited as the largest giant squid ever recorded.[nb 9]
Of the last one, Paxton wrote: "Sometimes mistakenly cited as 17.37 m (57.0 ft) 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] 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.[117]

The 19-foot (5.8 m) tentacle that fisherman Theophilus Picot hacked off a live animal on 26 October 1873. Picot estimated the total length of the squid at 60 ft (18 m).[118]

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 19 m (62 ft) 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 9 m (30 ft).[119] The misprint was reproduced in the English translation published the following year and was later propagated in a number of papers on giant squid.[119] With the Berzin specimen not being as large as originally reported, the longest giant squid recovered from a sperm whale is the 34 ft 5 in (10.49 m) 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).[120] Paxton considered the "longest visually estimated" TL to be the 60 ft (18 m) 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.[121]

Perhaps the largest of all recorded giant squid specimens was the one found floating at the surface off

lower rostral length of the beak, at 19.74 mm (0.777 in), gave an estimated dorsal mantle length of 215.3–306.0 cm (7.064–10.039 ft) and this, in turn, was used to estimate the total length at 11.025–15.664 m (36.17–51.39 ft).[119]

Supposed sucker scars
A dramatisation of an underwater encounter between the sperm whale and giant squid, from a diorama at the American Museum of Natural History

More extreme and outlandish giant squid size claims—belonging firmly in the realm of

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.[127] However, such scars are not necessarily of squid origin and may instead represent fungal growths or bite marks, with sea lampreys (Petromyzon marinus) being one possible source.[128] 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.[129]

A portion of sperm whale skin with giant squid sucker scars. In this widely reproduced image the largest sucker scars measure around an inch (2.5 cm) across.[130]

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.[131] These include the claim of Dozier (1976) that "an ordinary giant squid of 50 feet [15 m] leaves teeth-ringed sucker marks measuring between three and four inches [7.6–10.2 cm] across on a whale, but sperm whales have been captured with tentacle marks 18 inches [46 cm] 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. [3.9 in] in diameter being common. The claw marks take the form of scratches 2–3 m. [6.6–9.8 ft] in length, and appear to be of more frequent occurrence than sucker marks".[132] 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 90 ft [27 m], 130 ft [40 m] and even 200 ft [61 m] 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 32 ft [9.8 m] long specimen measured 114 in [3.2 cm] in diameter, and those on a 52-footer [16 m] about 2 in [5.1 cm]. Daniel (1925), however, examined sucker marks on the head of one cachalot which measured 312 in [8.9 cm] across, and others measuring up to 5 in [13 cm] 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 18 in [46 cm] 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 2 in [5.1 cm] in diameter, are old scars that have increased in size as the sperm whale grew.

tentacular clubs of Architeuthis, showing the enlarged suckers of the manus, which are the largest found on any of the giant squid's limbs

Perhaps the most extreme published claim, ridiculed by Ellis (1998a:142), appeared in Willy Ley's 1959 book, Exotic Zoology: "Toothed whales, vomiting in death struggle, have shown evidence of still larger kraken; in one case a 6-foot [1.8 m] piece of tentacle, with a diameter of 2 feet [0.6 m; 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 [0.6 m] in diameter".[133]

Marine biologist

binomial name for this super-sized species, were it ever to be discovered: Architeuthis halpertius.[134]

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,

tentacular club, called the manus, and among the specimens examined by Förch (1998:53) these reached a maximum diameter of 28–32 mm (1.10–1.26 in). Clarke (1980) wrote: "I have not yet seen conclusive evidence to suggest that sucker scars are larger than 3.7 centimetres [1.46 in] across".[138] According to Roper & Boss (1982:97)
, the largest suckers of the tentacular clubs reach 5.2 cm (2.0 in) in diameter.

Mass estimates
A dozen people attempting to move a giant squid weighing in excess of 200 kg (440 lb)[139]

It is now accepted that the giant squid has

Thimble Tickle,[nb 9] "would have weighed 2914 or 30 tons [26.5 or 27.2 tonnes] including the tentacles—a truly noble animal, being a little more than one-fifth the weight of the largest whale and larger than the whale sharks and basking sharks, the largest of all fishes".[143] Ellis characterised these estimates as "unfounded exaggerations".[142] In the revised edition of Natural History of Marine Animals, published in 1968, the authors reduced their estimate to less than 8 tonnes.[144]

Bernard Heuvelmans 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."[145] 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 [17 m] Thimble Tickle squid would have "probably weighed near 24 tons" is patently erroneous.[146]

On the subject of the Thimble Tickle specimen's mass, Wood (1982:190) referred to the work of Soviet zoologist and writer Igor Akimushkin:

According to Dr Igor Akimushkin (1965), the Russian teuthologist, a 12 m [39 ft] long giant squid will weigh 1 tonne [2,200 lb] if the head, mantle and arms combined make up half the total length. Since there is a 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 [6,200 lb] (i.e. the weight of a large bull hippopotamus), although 2 tonnes [4,400 lb] is probably a more realistic figure.

Giant Pacific octopus

The maximum size of the giant Pacific octopus (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
Enteroctopus dofleini[40]
Log–log plot showing relationship between interocular distance and mass in Enteroctopus dofleini[40]

In 1885, reporting on the longest octopus specimen reliably recorded up to that point, renowned malacologist William Healey Dall wrote:

In 1874 I speared an octopus in the harbor of

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 [4.9 m], giving the creature a spread from tip to tip of the longest pair of arms, of not less than thirty-two feet [9.8 m]. The arms toward the tips were all exceedingly slender, but rather stout toward the body, which was somewhat over a foot [30 cm] long. The largest suckers were two and a half inches [6.4 cm] in diameter; the whole creature nearly filled a large washtub. Parts of this specimen are now in the U. S. national museum.[147]

In an article for the National Marine Fisheries Service summarising knowledge on the giant Pacific octopus, High (1976:17–18) wrote:

Several octopuses in excess of 100 pounds [45 kg] 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 [32 kg] with a stretched length of 15 feet [4.6 m] 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 [272 kg] and measuring 32 feet [9.8 m] from arm tip to top. MacLean's photographs, unfortunately, were of poor quality. Smaller animals, to 400 pounds [181 kg], were occasionally taken in his commercial octopus fishing endeavor.

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.[nb 12]

Jock MacLean is also reported to have captured a 198 kg (437 lb) animal with an arm span of 8.5 m (28 ft) near Port Hardy, British Columbia, in March 1956.[150] Another giant specimen was caught off Santa Barbara, California, in 1945. Its weight was recorded as 182.3 kg (402 lb) and the surviving photograph makes it possible to estimate its total length at more than 3 m (9.8 ft) and arm span at 6–6.7 m (20–22 ft).[81] 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 [sic] 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 272 kg (600 lb) and with radial spans of over nine metres (30 feet) 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

digestive glands of wild giant Pacific octopuses, likely originating from their preferred prey, the red rock crab (Cancer productus).[152] A preliminary study found that aquarium animals fed equal quantities of raw sea food and live C. productus (caught locally in Elliott Bay) matured at a smaller size, reached a lower maximum weight (27 kg [60 lb] mean), and had higher concentrations of most heavy metals, than those fed solely on raw sea food (36 kg [79 lb] mean, including the aforementioned 43 kg [95 lb] specimen).[153]

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

Teuthologist Clyde Roper lying alongside a large giant squid (Architeuthis dux) specimen of almost 2 m (6.6 ft) ML
Reaching a mantle length of 2 m (6.6 ft), Onykia robusta is one of the largest squid species (the specimen shown here is considerably smaller).
A 52 lb (24 kg) Humboldt squid (Dosidicus gigas) caught off the southern Californian coast displaying deep red chromatophoric colouring.
National Aquarium in Washington, D.C.
Sepia apama
, the largest species of cuttlefish, is native to the southern coast of Australia.
Sepia pharaonis, a large and commercially important cuttlefish species from the Indian Ocean
Bobtail squids, such as this Euprymna berryi from East Timor, are some of the smallest of all cephalopods and are not known to attain a mantle length in excess of 10 cm (3.9 in).

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 (Mesonychoteuthis hamiltoni) with an estimated maximum mantle length of 3 m (9.8 ft) (Roper & Jereb, 2010c:173). Even greater mantle lengths have historically been reported for the giant squid (Architeuthis dux), but these have been discredited (see O'Shea & Bolstad, 2008).

Oegopsida (oegopsid squids)
Species Maximum mantle length References Notes
Mesonychoteuthis hamiltoni

(colossal squid)
≈300 cm (estimate) Roper & Jereb (2010c:173) The largest complete specimen, a mature female recovered from the
LRL, its beak is considerably smaller than the largest recovered from a sperm whale stomach (49 mm LRL; O'Shea & Bolstad, 2008; [Anonymous], N.d.). Maximum mantle lengths as great as 4 m have been estimated and reported in the past (Young, 2003; O'Shea & Bolstad, 2008). There are published claims of a very large section of gladius that would suggest a colossal squid measuring 5 m or more in mantle length (Wood, 1982:191; Bright, 1989:146).[nb 13]
Galiteuthis phyllura ? 265–275 cm (estimate) Nesis (1985); Nesis (1987:274); Ellis (1998a:149); Glaubrecht & Salcedo-Vargas (2004:65); Hoving & Robison (2017:47) Estimate based on 40 cm long arm and 115 cm tentacle from the Sea of Okhotsk.[nb 14] Roper & Jereb (2010c:165) write: "this is considered a doubtful record that might refer to total length; probably the maximum mantle length is less than 400 to 500 mm".
Architeuthis dux

(giant squid)
240 cm (female) Landman et al. (2004:686); O'Shea (2006); Roper & Shea (2013:114) Dorsal mantle length of female captured off Tasmania, Australia, reported by Landman et al. (2004:686) and cited by Roper & Shea (2013:114). Questionable records of up to 500 cm ML can be found in older literature (Roper & Jereb, 2010a:121). O'Shea & Bolstad (2008) give a maximum mantle length of 225 cm based on the examination of more than 130 specimens, as well as beaks recovered from sperm whales (which do not exceed the size of those found in the largest complete specimens). Paxton (2016a) accepts a maximum recorded ML of 279 cm, based on the Lyall Bay specimen reported by Kirk (1880:312), but this record has been called into question as the gladius of this specimen—which should approximate the mantle in length—was said to be only 190 cm long (Greshko, 2016).[nb 8]
Onykia robusta
(robust clubhook squid)
200 cm Norman (2000:174); Bolstad (2008:107); Okutani (2015b) Kubodera et al. (1998) give a maximum of at least 161.5 cm ML. The largest specimen seen by Bolstad (2008:107) had a mantle length of 197 cm (USNM 816872; specimen of indeterminate sex from 51°46.9′N 177°39.7′E / 51.7817°N 177.6617°E / 51.7817; 177.6617 (Onykia robusta specimen (197 cm ML))). Verrill (1876:237) reported a specimen with a mantle length of 232 cm (91.5 in) and a total length of 4.3 m (14 ft) (excluding the ends of the tentacles, which had been destroyed). Nesis (1987:192) likewise gave a maximum mantle length of 230 cm, but Roper & Jereb (2010i:364) wrote that "this old record might be in error", with the species commonly growing to 160 cm ML. Previously known as Moroteuthis robusta (see Bolstad, 2008; Bolstad, 2010).
Megalocranchia maxima 185 cm (female) Kubodera & Horikawa (2005:210) Size of female caught off
Okinawa, Japan, identified as "Megalocranchia cf. maxima" (see Kubodera & Horikawa, 2005:223 for photograph). This species is listed under the name Megalocranchia fisheri in many older sources. Tsuchiya & Okutani (1993), Roper & Jereb (2010c:171) and Okutani (2015a) give maximum of 180 cm, and Norman (2000:158) gives the same for M. fisheri. This species may also be conspecific with Megalocranchia abyssicola (Glaubrecht & Salcedo-Vargas, 2004:65
).
Taningia danae
(Dana octopus squid)
170 cm Nesis (1982); Roper & Jereb (2010h:266) The largest well documented specimen is a 160 cm ML mature female from the North Atlantic (Roper & Vecchione, 1993:449).
Dosidicus gigas

(Humboldt squid)
150 cm Wormuth (1976:38); Norman (2000:165); Glaubrecht & Salcedo-Vargas (2004:54) According to Wormuth (1976:38), specimens reaching 150 cm ML are "not uncommon" off Peru. Roper et al. (2010b:301) give a maximum mantle length of 120 cm for specimens off Chile and around 100 cm for northern populations, with a more typical mantle length of up to 50–80 cm. The review article of Nigmatullin et al. (2001)—based on c. 230 published papers on the species, in addition to other catch data—also gives a maximum mantle length of 120 cm.
Kondakovia longimana

(giant warty squid)
≈150 cm (estimate; female) Bolstad (2008:171) Estimated size of damaged female (NMV F109447; specimen with 21 mm LRL from 63°04.72′S 62°56.02′E / 63.07867°S 62.93367°E / -63.07867; 62.93367 (Kondakovia longimana specimen (150 cm ML))). O'Shea (2003b) estimated maximum mantle length as probably exceeding 115 cm. Largest complete specimen measured 108 cm ML (Lynnes & Rodhouse, 2002:1087; Roper & Jereb, 2010i:366).
Mastigoteuthis cordiformis
100 cm or more Roper & Jereb (2010g:253) Based on unpublished reports; largest verified ML is 70 cm (Roper & Jereb, 2010g:253).
Lepidoteuthis grimaldii
(Grimaldi scaled squid)
100 cm Roper & Jereb (2010e:240)
Myopsida (myopsid squids)
Species Maximum mantle length References Notes
Loligo forbesi

(long finned squid)
93.7 cm Maximum mantle length is 93.7 cm in males and 46.2 cm in females.[154][155]
Octopoda
(octopuses)
Species Maximum mantle length References Notes
Haliphron atlanticus

(seven-arm octopus)
69 cm (female) O'Shea (2002:1); O'Shea (2004a:9); Finn (2014a:227) Mantle length of incomplete 2.90 m TL mature female, measured defrosted and wet, prior to fixing. Isolated beaks of comparable size to that of this specimen were recorded by Clarke (1986:247–248). The sexually dimorphic males reach a mantle length of over 10 cm (Finn, 2014a:227).
Enteroctopus dofleini

(giant Pacific octopus)
at least 60 cm Norman (2000:214); Norman et al. (2014:124)
Sepiida
(cuttlefish)
Species Maximum mantle length References Notes
Sepia apama

(Australian giant cuttlefish)
50 cm Reid et al. (2005:68)
Sepia latimanus
(broadclub cuttlefish)
50 cm Reid et al. (2005:92)
Sepia hierredda <50 cm Reid et al. (2005:88)
Sepia officinalis

(European common cuttlefish)
49 cm Reid et al. (2005:99)
Sepia pharaonis

(pharaoh cuttlefish)
42 cm Reid et al. (2005:107)
Sepia lycidas
(kisslip cuttlefish)
38 cm Reid et al. (2005:96)
Sepia ramani 37.5 cm Reid et al. (2005:114)
Vampyromorphida (vampire squid) – single extant species
Species Maximum mantle length References Notes
Vampyroteuthis infernalis

(vampire squid)
13 cm Nesis (1982); Norman & Finn (2014:269)
Sepiolida
(bobtail squids)
Species Maximum mantle length References Notes
Austrorossia antillensis 9 cm Reid & Jereb (2005:192)
Rossia pacifica 9 cm (female) Reid & Jereb (2005:185) Males grow to 4.5 cm in mantle length.
Rossia macrosoma 8.5 cm Reid & Jereb (2005:184) More typically the mantle length is 2.0–6.0 cm.
Neorossia caroli 8.3 cm (female) Reid & Jereb (2005:190) Males grow to 5.1 cm in mantle length.
Spirulida (spirula) – single extant species
Species Maximum mantle length References Notes
Spirula spirula

(ram's horn squid)
rarely exceeds 4.5 cm Reid (2005:211)

Total length

'Archie', a giant squid specimen at the Natural History Museum in London, measures 8.62 m (28.3 ft) in total length (see Ablett, 2012 for more on this specimen)
A bigfin squid (cf. Magnapinna), one of the longest known cephalopods. This specimen was filmed in October 2000 by DSV Alvin in the Gulf of Mexico, at 1,940 m (6,360 ft) depth.
Ommastrephes bartramii from northern Hawaiian
waters. This species grows to a total length of 2 m (6.6 ft).
Enteroctopus dofleini
can exceed 3 m (9.8 ft) in total length.

The longest scientifically documented specimens belong to the giant squid, with a maximum total length of 14–15 m (46–49 ft) (Roper & Shea, 2013:114). Despite its proportionally shorter tentacles, the colossal squid 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.

Teuthida
(squids)
Species Maximum total length References Notes
Architeuthis dux

(giant squid)
14–15 m (female) Roper & Shea (2013:114) Based on a 40-year data set of more than 50 specimens, Roper & Shea (2013:114) suggest an average total length at maturity of 11 m and a "rarely encountered maximum length" of 14–15 m. Of the nearly 100 specimens examined by Roper, the largest was "46 feet (14 m) long" (Cerullo & Roper, 2012:22). O'Shea & Bolstad (2008) give a maximum total length of 13 m 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). O'Shea estimated the maximum total length for males at 10 m (O'Shea, 2003a).

Older records of 18 m 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). Paxton (2016a) performed a statistical analysis using literature records of giant squid specimens and concluded that "squid with a conservative TL of 20 m would seem likely based on current data", but the study has been heavily criticised by experts in the field (Greshko, 2016).

Mesonychoteuthis hamiltoni

(colossal squid)
approaching 9–10 m (estimate) Roper & Jereb (2010c:173) The maximum confirmed total length for this species is 6 m (Rosa et al., 2017). Two specimens of M. hamiltoni recovered from the stomachs of sperm whales between 1956 and 1957 off the South Shetland Islands and South Orkney Islands—both initially identified as Architeuthis—reportedly measured around 10 and 12 m, respectively (Sweeney & Roper, 2001:56; see Korabelnikov, 1959:103 and Yukhov, 1974:62). Estimated maximum lengths as great as 12–14 m have appeared in the popular literature (see Anderton, 2007).
cf.
Magnapinna

(bigfin squid)
≈7 m (estimate) Vecchione et al. (2001a:2505); Vecchione et al. (2001b); Glaubrecht & Salcedo-Vargas (2004:67); Roper & Jereb (2010f:247) Estimate based on specimen observed by commercial ROV operated from the oil-drilling ship Millennium Explorer in January 2000, Mississippi Canyon, Gulf of Mexico (28°37′N 88°0′W / 28.617°N 88.000°W / 28.617; -88.000 (Bigfin squid observed from ROV, January 2000)), at a depth of 2195 m (Vecchione et al., 2001b). Bolstad (2003) gives an estimate of at least 8 m TL for the largest observed specimen.
Asperoteuthis acanthoderma 5.5 m (+) Tsuchiya & Okutani (1993) Total length of immature specimen measuring 0.45 m ML. Much larger specimens of up to 92 cm ML are known (see Kubodera & Horikawa, 2005:223 for photograph).
Onykia robusta
(robust clubhook squid)
4.3 m (14 ft) (+) Verrill (1876:237) Total length of specimen missing ends of tentacles, with a mantle length of 2.32 m (91.5 in) according to Verrill (1876:237). Glaubrecht & Salcedo-Vargas (2004:66) give maximum total length of 4–6 m. Previously known as Moroteuthis robusta (see Bolstad, 2008; Bolstad, 2010).
Galiteuthis phyllura ? over 4 m (estimate) Nesis (1985); Ellis (1998a:149); Glaubrecht & Salcedo-Vargas (2004:65) Estimate based on 0.40 m long arm and 1.15 m tentacle from the Sea of Okhotsk.[nb 14] Roper & Jereb (2010c:165) cast doubt on the validity of this record.
Dosidicus gigas

(Humboldt squid)
possibly up to 3.7 m (12 ft) Clarke (1966:117); Glaubrecht & Salcedo-Vargas (2004:59) Specimens from the
northern hemisphere are much smaller, with those off the Californian coast reaching total lengths of less than 1.7 m (Glaubrecht & Salcedo-Vargas, 2004:59). Roper et al. (2010b:301) give maximum total length of close to 2.5 m for specimens off Chile
.
Megalocranchia maxima 2.7 m (+) (female) Young & Mangold (2010) Total length of 1.65 m ML female taken off Hawaii (see Young & Mangold, 2010 for photograph). Larger specimens of up to 1.85 m ML have been recorded, and these clearly exceed 2.7 m TL (see Kubodera & Horikawa, 2005:223 for photograph).
Taningia danae
(Dana octopus squid)
2.3 m (female) Roper & Vecchione (1993:444) Total length of mature female measuring 160 cm in mantle length, taken from frozen specimen.
Kondakovia longimana

(giant warty squid)
2.25 m (+) Lynnes & Rodhouse (2002:1087) Size of largest complete specimen (1.08 m ML), found floating at surface off South Orkney Islands (see also Carrington, 2000). Much larger specimens up to an estimated 1.5 m ML are known (Bolstad, 2008:171).
Octopoda
(octopuses)
Species Maximum total length References Notes
Enteroctopus dofleini

(giant Pacific octopus)
>6.1 m Cosgrove (1987) Norman et al. (2014:124) give the maximum total length as "more than 3 m". Questionable length records of up to 9.8 m can be found in the literature (see High, 1976:18).
Cirrina gen. et sp. indet. over 4 m (estimate) Voss (1988); Vecchione et al. (2008) Estimate based on photographic record; finned octopods are known with certainty to reach at least 1.7 m in total length (Collins et al., 2001).
Haliphron atlanticus

(seven-arm octopus)
4 m (estimate; female) O'Shea (2004a:9); Finn (2014a:227) Estimate based on incomplete 2.90 m mature female, measured defrosted and wet, prior to fixing. Isolated beaks of comparable size to that of this specimen were recorded by Clarke (1986:247–248). Males are estimated to reach a total length of 21 cm (Finn, 2014a:227) and perhaps as much as 30 cm (Norman et al., 2002:733).
Vampyromorphida (vampire squid) – single extant species
Species Maximum total length References Notes
Vampyroteuthis infernalis

(vampire squid)
≈30 cm Norman & Finn (2014:269)

Mass

Museum of New Zealand Te Papa Tongarewa
. It is the most massive extant cephalopod on record.
The largest documented specimen of T. danae, preserved at the National Museum of Natural History. It originally weighed 161.4 kg (356 lb) and had a mantle length of 160 cm (5.2 ft).
A very large mature female of Onykia robsoni with a mantle length of 88.5 cm (2.90 ft) and total weight of 11.1 kg (24 lb)
Lepidoteuthis grimaldii female measuring 61.7 cm (2.02 ft) in mantle length and weighing 4.07 kg (9.0 lb), from the Chatham Rise off New Zealand (note the prominent dermal cushions, likely used for buoyancy)
The maximum weight of the giant Pacific octopus (Enteroctopus dofleini) has been much debated, with numerous reports of specimens exceeding 100 kg (220 lb)
S. apama
in both mantle length and mass.

The heaviest known cephalopod, and the largest living invertebrate, is the colossal squid. The largest recorded specimen of this species, caught in the Ross Sea in 2007, weighed 495 kg (1,091 lb). 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.

Teuthida
(squids)
Species Maximum mass References Notes
Mesonychoteuthis hamiltoni

(colossal squid)
495 kg (female) [Anonymous] (N.d.); Guerra & Segonzac (2014:65); Rosa et al. (2017) Weight of mature female specimen caught in February 2007, measured after thawing. This specimen was originally estimated to weigh 450 kg (Anderton, 2007). Several other specimens with weights in the hundreds of kilograms have been recorded. Beaks recovered from sperm whale stomachs indicate the existence of even larger specimens, perhaps weighing as much as 600–700 kg ([Anonymous], N.d.).
Architeuthis dux

(giant squid)
275 kg (female) O'Shea (2003a); Grist & Jackson (2007:386); Guerra & Segonzac (2014:65) Maximum size based on the examination of some 105 specimens by O'Shea (2003a), as well as beaks recovered from sperm whales (which do not exceed the size of those found in the largest complete specimens). Maximum weight for males has been estimated at 150 kg (O'Shea, 2003a; see also Grist & Jackson, 2007:386), though heavier specimens have occasionally been reported (see Deagle et al., 2005 for 190 kg specimen, Hofilena, 2014 for 163 kg specimen). Roper & Jereb (2010a:121) give a maximum weight of up to 500 kg, and "possibly greater". Discredited weights of as much as a tonne or more are not uncommon in older literature (O'Shea & Bolstad, 2008).
Taningia danae
(Dana octopus squid)
161.4 kg (female) Roper & Jereb (2010h:266) Weight of 160 cm ML mature female from North Atlantic. Specimen weighed prior to freezing (Roper & Vecchione, 1993:444). According to Roper & Jereb (2010h:266), the previously reported maximum weight of 61.4 kg (based on the same specimen) stems from a typographical error in the original paper of Roper & Vecchione (1993). This lower value was repeated by a number of subsequent authors, including Santos et al. (2001:355) and Kubodera et al. (2006:1029).
Onykia robusta
(robust clubhook squid)
50 kg Roper et al. (1984); Roper & Jereb (2010i:364); Guerra & Segonzac (2014:65); Okutani (2015b) Previously known as Moroteuthis robusta (see Bolstad, 2008; Bolstad, 2010).
Dosidicus gigas

(Humboldt squid)
50 kg Nigmatullin et al. (2001:10); Roper et al. (2010b:301); [Anonymous] (N.d.) Commonly reaches a maximum weight of around 20–30 kg (Roper et al., 2010b:301). In their introduction to the family Ommastrephidae, Roper et al. (2010b:269) give a maximum weight of 55–65 kg, but this is contradicted later in the same work by the 50 kg figure in the main species account. Guerra & Segonzac (2014:65) give a maximum weight of 90 kg.
Kondakovia longimana

(giant warty squid)
50 kg (estimate) Guerra & Segonzac (2014:65) Largest complete specimen, found floating at surface off South Orkney Islands, had a wet weight of 29 kg and a mantle length of 108 cm (Lynnes & Rodhouse, 2002:1087; see also Carrington, 2000), but a damaged female specimen with an estimated mantle length of around 150 cm is known (Bolstad, 2008:171).
Thysanoteuthis rhombus
(diamondback squid)
30 kg Miyahara et al. (2006); Roper & Jereb (2010k:385) Probably exceeds the recorded mass of 30 kg according to Roper & Jereb (2010k:385).
Ommastrephes bartramii

(neon flying squid)
20–25 kg (female) Roper et al. (2010b:296) Maximum size of specimens from North Atlantic and Southern Hemisphere (where males reach 2–2.2 kg). Females from the North Pacific are smaller (6 kg), but males may be larger (2–2.9 kg) (Roper et al., 2010b:296).
Megalocranchia maxima 23.9 kg (52.7 lb) (+) [Anonymous] (2015b); Mosendz (2015) Mass of specimen found floating dead off Hawaii, estimated to measure at least 2.1 m (7 ft) TL, tentatively identified as Megalocranchia fisheri. Larger specimens reaching and even exceeding 2.7 m TL have been recorded, though were apparently not weighed (see Kubodera & Horikawa, 2005:223; Young & Mangold, 2010).
Onykia robsoni
(rugose hooked squid)
11.1 kg (female) Vecchione et al. (2011) Weight of mature female (88.5 cm ML) caught in bottom trawl at 685–700 m depth over Chatham Rise (44°21′S 175°32′E / 44.350°S 175.533°E / -44.350; 175.533 (Onykia robsoni specimen (88.5 cm ML))). Previously known as Moroteuthis robsoni (see Bolstad, 2008; Bolstad, 2010).
Octopoda
(octopuses)
Species Maximum mass References Notes
Enteroctopus dofleini

(giant Pacific octopus)
? >180 kg Norman et al. (2014:124) Cosgrove (1987) and Cosgrove & McDaniel (2009:69) gave a maximum confirmed weight of 71 kg for a live specimen collected in the mid-1960s (McClain et al., 2015). There exists a dubious record of a 272 kg specimen which is sometimes cited as the largest known (see High, 1976:18; Hochberg & Fields, 1980:436; Lewy, 2002:65), although it was never actually collected and weighed (Newman, 1994:66; McClain et al., 2015). Norman et al. (2014:124) accept a maximum weight of at least 180 kg, which approximates the 182.3 kg reported for a specimen caught off Santa Barbara, California, 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 50 kg (Cosgrove & McDaniel, 2009:71). It is possible that the maximum size of the species has decreased over this period, perhaps due to bioaccumulation of toxicants (Anderson, 2003:3; Cosgrove & McDaniel, 2009:71).
Haliphron atlanticus

(seven-arm octopus)
75 kg (estimate; female) O'Shea (2004a:9) Estimate based on incomplete 61.0 kg mature female, measured defrosted and wet, prior to fixing. Isolated beaks of comparable size to that of the present specimen were recorded by Clarke (1986:247–248).
Sepiida
(cuttlefish)
Species Maximum mass References Notes
Sepia apama

(Australian giant cuttlefish)
>10.5 kg Reid et al. (2005:68)
Sepia latimanus
(broadclub cuttlefish)
10 kg Reid et al. (2005:92)
Sepia hierredda >7.5 kg Reid et al. (2005:88)
Sepia lycidas
(kisslip cuttlefish)
5 kg Reid et al. (2005:96)
Sepia pharaonis

(pharaoh cuttlefish)
5 kg Reid et al. (2005:107)
Sepia officinalis

(European common cuttlefish)
4 kg Reid et al. (2005:99)

Shell diameter

Eggcases of six extant Argonauta species (not to scale)
A giant specimen of Argonauta hians from Taiwan, which—at roughly 121.5 mm (4.78 in) in diameter—approximates the length of the official world record size shell.
Young A. argo female with eggcase
N. pompilius
Nautilus belauensis off Palau
Spirula spirula

Nautiluses 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 cuttlebones of cuttlefish, the gladii of squids and the vampire squid, the winged shells of cirrate octopods, and the spiral shells of Spirula. 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

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, 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 (0.0039 in), as is standard in conchology
.

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. (N.d.) is the current, continuously updated online database. The registry only covers the shells of nautiluses and Spirula and the eggcases of Argonauta.

Octopoda (octopuses) – all extant Argonauta
species listed
Species Maximum shell diameter References Notes
Argonauta argo
(greater argonaut)
300.0 mm Pisor (2008:22); Barbier et al. (N.d.) Pisor (2008:22) listed this size for a specimen from Australia (registered in 1991; in collection of SIO). Barbier et al. (N.d.) list exactly the same size for a specimen from the Philippines (year given as 1985; in private collection of Beals Marty). For a discussion of maximum shell size in this species, see Finn (2013:199). The largest literature record (and the only one to exceed the official world record size) appears to be the rough upper limit of 12 in (304.8 mm) given by Webb (1945:13) for the species as a whole (Finn, 2013:199).

Under

Argonauta pacificus (as A. pacifica) by Pisor (2005:12). Both A. cygnus and A. pacificus are considered synonyms of A. argo by Finn (2013) and Finn (2014b)
.

Argonauta nodosus

(knobbed argonaut)
292.0 mm Pisor (2008:22) Size of a specimen from South Australia (registered in 1977; in collection of AMNH). Barbier et al. (N.d.) list a record of 204.0 mm for a specimen from the "Tasmania area", Australia (year given as 2000; in private collection of B. Henke). For a discussion of maximum shell size in this species, see Finn (2013:167); a number of unconfirmed reports put the maximum size beyond 300 mm.
Argonauta hians
(muddy argonaut)
121.61 mm Barbier et al. (N.d.) Size of a specimen from the Gulf of Aqaba, Red Sea (year given as 1995; in private collection of Simon Weigmann). Pisor (2008:22) listed a record of 112.6 mm for a specimen from the Philippines (registered in 1988; in private collection of Victor Dan). For a discussion of maximum shell size in this species, see Finn (2013:186); none of the records discussed therein exceed the current world record specimen.
Argonauta boettgeri[nb 15]
108.03 mm Barbier et al. (N.d.) Size of a specimen taken from the
Zhejiang Province by a local fisherman (year given as 2005; in private collection of Simon Weigmann). Pisor (2008:22) listed a record of 102.2 mm for a specimen from the Philippines (collected in 2005; in collection of Havelet Marine). Pisor (2005:12) listed a record of 67.0 mm for a specimen from Mozambique, which is the locus classicus
of this species (registered in 2003; in private collection of Pete Stimpson).
Argonauta cornutus[nb 15]
98.7 mm Barbier et al. (N.d.) Size of a specimen from western Mexico (year given as 1985; in collection of W. D. Schroeder). Pisor (2008:22) listed possibly the same specimen, also from western Mexico, at 98.6 mm (collected in 1999; in private collection of W. D. Schroeder).
Argonauta nouryi 95.5 mm Pisor (2008:22); Barbier et al. (N.d.) Size of a specimen from
A. cornutus
, which Finn treats as a synonym of A. nouryi).
Nautilida (nautiluses) – all extant species listed
Species Maximum shell diameter References Notes
Nautilus pompilius pompilius

(emperor nautilus)
254.0 mm Pisor (2008:121); Barbier et al. (N.d.) Size of a specimen from Indonesia (registered in 2003; in private collection of Pete Stimpson), listed as N. p. pompilius. Hutsell et al. (1997:48) listed a 253.0 mm specimen, also from Indonesia (collected in 1983; in private collection of Cecelia Abbott). Harasewych & Moretzsohn (2010:632) give a maximum shell diameter of 268 mm for this species, but this is based on an erroneous record.[nb 16]

Under N. repertus (which is treated here in synonymy with N. p. pompilius; Jereb (2005:53) considered it a "questionable species"), Pisor (2005:93) listed a 230.0 mm record for a specimen from Indonesia (registered in 2000; in private collection of Pete Stimpson), Pisor (2008) did not include the taxon at all, while Barbier et al. (N.d.) list a record of 242.07 mm for a specimen from India (no year given; in private collection of Simon Weigmann).

The largest

Zamboanga in the Philippines
(year given as 2013; in collection of Havelet Marine).

Nautilus stenomphalus
(white-patch nautilus)
239.39 mm Barbier et al. (N.d.) Size of a specimen from
Timor Island, Indonesia (year given as 2009; in private collection of Simon Weigmann). Under N. pompilius f. stenomphalus, Pisor (2008:121) listed a maximum shell diameter of 221.0 mm for a specimen from the Philippines
(no year given; in collection of Havelet Marine).
Nautilus belauensis
(Palau nautilus)
239 mm Grulke (2016:76) Grulke (2016:76) gives an adult shell size range of 180–239 mm, and a mean adult shell diameter of 200 mm. Jereb (2005:54) gives 226 mm as the maximum size for the species, with no reference to a particular specimen. Pisor (2008:121) and Barbier et al. (N.d.) list a record of 221.0 mm for a specimen from Babeldaob, Palau (year given as 1980; in collection of Havelet Marine).
Nautilus pompilius suluensis
220.0 mm Barbier et al. (N.d.) Size of a specimen from the Philippines (year given as 2000; in private collection of Pete Stimpson). Pisor (2008:121) listed a maximum shell diameter of 148.0 mm for a specimen from the Philippines (registered in 2000; in private collection of Pete Stimpson). N. p. suluensis is a dwarf form from the Sulu Sea that has the smallest mean shell diameter of all known extant nautilus populations, at 115.6 mm (Dunstan et al., 2011).
Allonautilus scrobiculatus
(crusty nautilus)
215.0 mm Pisor (2005:93) Size of a specimen from the Philippines (registered in 2000; in private collection of Pete Stimpson), listed as Nautilus scrobiculatus. Pisor (2008) did not include this species at all. Barbier et al. (N.d.) list a record of 214.0 mm for a specimen from Indonesia (year given as 2013; in private collection of Pete Stimpson).
Nautilus macromphalus
(bellybutton nautilus)
180.62 mm Barbier et al. (N.d.) Size of a specimen from New Caledonia (year given as 2008; in private collection of Simon Weigmann). Pisor (2008:121) listed a maximum shell diameter of 180.0 mm for a specimen from New Caledonia (collected in 1995; in private collection of Kent Trego).
Allonautilus perforatus around 180 mm Jereb (2005:55); Grulke (2016:83) Given as the maximum size for the species, with no reference to a particular specimen. Jereb (2005:55) considered A. perforatus a "[v]ery rare form of questionable validity".
Spirulida (spirula) – single extant species
Species Maximum shell diameter References Notes
Spirula spirula

(ram's horn squid)
28.8 mm [Anonymous] (2003c) Size of a specimen from
Phuket Island, Thailand (collected c. 2000; in collection of Havelet Marine; see [Anonymous], 2006
for online record).

Extinct taxa

Westfälisches Museum für Naturkunde in Münster
, but many casts exist.
The earliest discovered fossil of P. seppenradensis, as it appeared at the Westphalian Museum of Natural History in 1895. A human skeleton provided scale, while an oil painted background reconstructed the living chamber and animal itself, together with assorted Cretaceous sealife.
National Museum of Natural History in Sofia
.
heteromorph ammonite
Fossilised guards of the Jurassic belemnites Megateuthis gigantea (top two) and Megateuthis aalensis
Acroteuthis subquadrata
Endoceras orthocones
Middle Ordovician
Ammonoidea (ammonoids)
Species Maximum shell diameter (length for heteromorphs) References Notes
Parapuzosia seppenradensis 2–3.5 m (estimate) Landois (1895:100); Landois (1898:27); Teichert & Kummel (1960:6); Summesberger (1979:128); Holland (1987:6); Kennedy & Kaplan (1995:21); Lewy (2002:66); frim et al. (2021) Widely recognised as the largest ammonite specimen ever found (
living chamber, assuming living chamber took up one-fourth of the outer whorl. Teichert & Kummel (1960:6) suggested an even larger shell diameter of around 3.5 m for this specimen, assuming the body chamber extended for three-fourths to one full whorl. Landois (1898:27) estimated the total live weight at 1456 kg, of which the shell would constitute 705 kg. The fossil itself weighs around 3.5 tonnes (Beer, 2015). A smaller specimen of 1.36 m was found in the same quarry some years earlier (Beer, 2015). In 1971 a portion of an ammonite possibly surpassing the Seppenrade specimen was reportedly found in a brickyard in Bottrop, western Germany (Beer, 2015). In 2021, diameter of 2 m is estimated for the largest specimen.[156]
Parapuzosia bradyi >1.8 m (estimate) Larson et al. (1997:44); Lewy (2002:66) Largest known North American ammonite. Estimate based on incomplete specimen measuring 1.37 m in diameter (missing at least half a
body chamber
).
Peltoceratinae gen. et sp. indet. 1.78 m (estimate) Poulton (1989) Estimate based on small portion of
"Titanites" occidentalis
(about 35%), and assumes a constant rate of expansion. More crude calculations give a circular diameter of 2–2.4 m (best fit of the specimen's outline to a curve yields 2.16 m estimate).
Eopachydiscus sp. 1.67 m Grulke (2014:125) This specimen, from the Albian Duck Creek Formation of Texas, has been exhibited at the Tucson Fossil Show and in a New York auction.
Pachydesmoceras cf. pachydiscoide 1.65 m (estimate) Kin & Niedźwiedzki (2012:19) Estimate based on 0.98 m diameter specimen representing an apparently complete
body chamber is also known (Kin & Niedźwiedzki, 2012:17
).
Lytoceras taharoaense 1.5 m Stevens (1978a:3); Stevens (1978b:2); Stevens (1979a:33); Stevens (1979b:6); Stevens (1979c:166); Stevens (1985:153); Grulke (2014:126) Size based on essentially complete shell with only some damage to the aperture.
Mesopuzosia mobergi <1.5 m Kin & Niedźwiedzki (2012:19)
Parapuzosia austeni <1.5 m Kin & Niedźwiedzki (2012:19) Puzosia mayoriana is a synonym.
Moutoniceras sp. 1.47 m [heteromorph] Grulke (2014:126) In private collection of Wolfgang Grulke, according to whom it is likely the largest
sympatric Gassendiceras heteromorphs. Its unrolled shell length would have exceeded 3 m (Grulke, 2014:126). A specimen claimed to be very slightly larger at 1.48 m was auctioned in September 2015 ([Anonymous], 2015a
).
Parapuzosia bosei 1.45 m Scott & Moore (1928:276); Lewy (2002:66) From the Austin Chalk of the Rio Grande region, Texas. The largest known specimen was reported by Scott & Moore (1928:273) to be 4 ft 9 in (1.45 m) in diameter and "impossible to extract from its matrix". The authors found "[m]any others only slightly smaller", of which three were collected in 1928 and deposited at Texas Christian University (Scott & Moore, 1928:273–274).
Parapuzosia americana 1.37 m (estimate) Scott & Moore (1928:276) From the Austin Chalk of the Rio Grande region, Texas.
"Titanites" occidentalis 1.37 m Frebold (1957:66); Westermann (1966) Size based on specimen consisting of an imprint and part of the last whorl preserved as an internal mould.
Diplomoceras maximum >1 m [heteromorph] Olivero & Zinsmeister (1989)
Tropaeum imperator almost 1 m Grulke (2014:126) Largest ammonite known from Australia. Grulke (2014:126) writes: "No exact size is available but it could be almost 1 m across".
Belemnoidea (belemnoids)
Species Maximum rostrum measurements References Notes
Megateuthis
sp.
0.7 m TL (Dvms: 30 mm; Dvma: 50 mm) Schlegelmilch (1998:1); Weis & Mariotti (2007:166); Iba et al. (2015:23–24) Megateuthis elliptica is "the longest belemnite species known", with rostra from the Humphriesianum Zone in Rumelange and Luxembourg reaching 60–70 cm (Weis & Mariotti, 2007:166). The whole animal is estimated to have been 3–5 m long (Eyden, 2003a). Fuchs and Stinnesbeck (2021) estimated total mantle length of 2.22 m.[157]
Belemnitina gen. et sp. indet. ? TL (Dvms: 30 mm; Dvma: ?) Iba et al. (2015:23) Known from a single incomplete rostrum (TCSM-J1-0001) from the Pliensbachian Teradani Formation in Teradani, Toyama Prefecture, Japan. The specimen is missing the apical and alveolar regions and comprises only the middle (stem) region of the rostrum. It measures 45 mm in total length by 30 mm and 25 mm across at the anterior and posterior ends, respectively. Iba et al. (2015:23) wrote: "In the Belemnitina, the diameter of the alveolar region is generally larger than those of the apical and stem regions. Thus maximum rostrum diameter of the Teradani specimen is estimated to reach much more than 30 mm."
Acroteuthis sp. ? TL (Dvms: 39 mm; Dvma: 42 mm) Iba et al. (2015:23) One of "the largest belemnites ever observed", with a rostrum comparable to that of the indeterminate belemnitinid from Teradani.
Pachyteuthis sp. ? TL (Dvms: 39 mm; Dvma: 40 mm) Iba et al. (2015:23) One of "the largest belemnites ever observed", with a rostrum comparable to that of the indeterminate belemnitinid from Teradani.
Belemnitina gen. et sp. indet. ? TL (Dvms: ?; Dvma: >33 mm) Iba et al. (2015:23) From the Hettangian Niranohama Formation of northeastern Japan. One of "the largest belemnites ever observed", with a rostrum comparable to but likely slightly smaller than that of the indeterminate belemnitinid from Teradani.
Nautiloidea
(nautiloids)
Species Maximum shell length References Notes
Endoceras giganteum 5.733 m (estimate) Klug et al. (2015:270) Estimate based on incomplete 3-metre-long shell deposited at the
body chamber-to-phragmocone ratio of 1:2 and wrote that this was likely "the largest fragment of an endoceroid cephalopod on display anywhere in the world". However, Klug et al. (2015:270) estimated the total length of the complete shell at 5.733 m, with a volume of 158.6 litres. From the Katian of New York (Klug et al., 2015:270). The published literature includes unconfirmed reports of even larger endocerids. Frey (1995) mentioned length of 6 m as maximum size for genus Cameroceras
, although this author support theory that some large specimens of Endoceras belong to Cameroceras instead.
Endoceras proteiforme 3.0–4.6 m (10–15 ft) Clarke (1897:778); Teichert & Kummel (1960:1) Size based on "entire shells" (Clarke, 1897:778).
Rayonnoceras solidiforme 2.8 m (estimate) Klug et al. (2015:270) From the
Visean of Arkansas
. Shell volume estimated at 62.5 litres.
Deiroceras hollardi 2.6 m (estimate) Klug et al. (2015:270) From the early Emsian of "Jebel Mdouar". Shell volume estimated at 68.3 litres.
Cameroceras turrisoides c. 2 m (estimate) Kröger & Ebbestad (2014) From the Katian of Sweden. Estimated after maximum diameter (165 mm).[158][159]
Actinocerida gen. et sp. indet. 1.911 m (estimate) Klug et al. (2015:270) From the
Llandovery of Gotland
. Shell volume estimated at 8.9 litres.
Orthocerida gen. et sp. indet. 1.783 m (estimate) Klug et al. (2015:270) From the
Ludlow of Gotland
. Shell volume estimated at 4.1 litres.
Ormoceras TUG 1308-1 1.72 m (estimate) Klug et al. (2015:270) From the Sandbian of Estonia. Shell volume estimated at 2.7 litres.
Ormoceras giganteum MB.C.11940 1.71 m (estimate) Klug et al. (2015:270) From the Darriwilian. Shell volume estimated at 2.7 litres.
Lambeoceras lambii 1.405 m (estimate) Leith (1942:130); Teichert & Kummel (1960:4) Estimate based on incomplete 1.155 m long shell.
Orthoceras regarium 1.39 m (estimate) Klug et al. (2015:270) From the
Wenlock of Joachimsthal.[nb 17]
Shell volume estimated at 5.1 litres.
Temperoceras aequinudum 1.333 m (estimate) Klug et al. (2015:270) From the Lochkovian of "Ouidane Chebbi". Shell volume estimated at 9.2 litres.
Zeravshanoceras priscum 1.299 m (estimate) Klug et al. (2015:270) From the Eifelian. Shell volume estimated at 1.6 litres.
Ordogeisonoceras amplicameratum >1.25 m Frey (1995:40) Shell diameter up to 10.5 cm. Originally described as Orthoceras amplicameratum. Orthoceras ludlowense is considered a synonym.
Cameroceras hennepini <1.2 m (4 ft) (estimate) Clarke (1897:779) Size estimate based on "the most complete of the fragments which represent it".
Actinoceras vaughanianum 1.198 m (estimate) Klug et al. (2015:270) From the Serpukhovian of Oklahoma. Shell volume estimated at 8.7 litres.
Polygrammoceras? cf. P. sp. A 1.13 m (estimate) Frey (1995:69) Estimate based on a "single, very large fragment of a phragmocone". Shell diameter to 9.0 cm.
Plagiostomoceras sp. 1.1 m (estimate) Klug et al. (2015:270) From the Givetian of Onondaga, New York. Shell volume estimated at 0.0052 litres.
Endoceras decorahense 1.06 m (estimate; phragmocone only) Miller & Kummel (1944); Teichert & Kummel (1960:2) Size estimate based on two portions of an internal mould of the phragmocone, measuring 62.5 cm and 32 cm, with an estimated missing middle section of 11.5 cm.
Proterovaginoceras incognitum 1 m (estimate) Klug et al. (2015:270) From the Dapingian of Jämtland, Sweden. Shell volume estimated at 0.8 litres.
Teuthida
(squids)
Species Maximum mantle length References Notes
Yezoteuthis giganteus ≈1.7 m (estimate) Tanabe et al. (2006:142) Size estimate based on preserved upper jaw measuring 97.0 mm in maximum length, similar to that of the largest giant squid (Architeuthis dux). Tanabe et al. (2006:143) wrote that this species "appears to be the largest fossil coleoid ever described".
Octopodiformes
Species Maximum mantle length References Notes
Enchoteuthis melanae up to 2 m (estimate) Eyden (2003b); Fuchs et al. (2020) Total length estimated to be up to 3 m. Tusoteuthis longa is likely to be invalid, and largest specimen should belongs to E. melanae.[160]
Leptotheuthis 1.3 m (gladius length) Fuchs and Stinnesbeck (2021) Reference spells "Leptotheuthis".[157]
Eromangateuthis soniae 1.2 m (gladius length) Fuchs (2019) Size based on gladius from Queensland, Australia.[161] A second gladius measuring more than a metre and showing possible evidence of predation by Kronosaurus is also known (Eyden, 2003b).
Trachyteuthis 0.8 m (gladius length) Fuchs and Stinnesbeck (2021) Size given for Early Cretaceous species.[157]
Nanaimoteuthis hikidai ≈0.7 m (estimate) Tanabe et al. (2015) Estimated from hood length of lower jaw with proportion of vampire squid.[96] Authors also estimated mantle length from fossil vampyromorphs unofficially, resulting ≈1.6 m mantle length.[162]
Nanaimoteuthis yokotai ≈0.54 m (estimate) Tanabe et al. (2010) Estimated from hood length of lower jaw with proportion of vampire squid.[163]
Sister group of decapodiformes
Species Maximum mantle length References Notes
Longibelus matsumotoi (?) 91.1-98.9 cm (estimate) Tanabe and Misaki (2023) Estimated from rostral length of lower jaw, with proportion of Spirula, giant squid and colossal squid.[97]

Anatomical superlatives

Eyes

Preserved giant squid eye
Kermadec Arc off New Zealand. Gonatids such as this have proportionately slightly larger eyes than do giant squid.[164]

The

ichthyosaurs are known to have approached these dimensions,[167] with some species having eyes up to 35 cm (14 in) in diameter.[168]

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.[169] 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.[164] Gonatids and the loliginids Loligo and Lolliguncula also have proportionately somewhat larger eyes than Architeuthis.[164] Some sources state that the vampire squid (Vampyroteuthis infernalis) has the largest eyes of any animal relative to its size, with a 15 cm (5.9 in) specimen having eyes around 2.5 cm (0.98 in) in diameter.[170]

Iridoteuthis iris is an extreme example of a sepiolid with disproportionately large eyes

There is some debate in the scientific community as to the evolutionary reason behind the extremely large eyes of giant and colossal squids.

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 axons can exceed 1 mm (0.039 in) in diameter: 100 to 1000 times the thickness of mammalian axons. The axons of the Humboldt squid (Dosidicus gigas) are exceptional in that they can reach a diameter of as much as 1.5 mm (0.059 in), and those of Loligo forbesii can also exceed 1 mm.[172] Such was the importance of Humboldt squid to electrophysiology research that when the animals migrated out of reach of Chilean fishermen in the 1970s "it led to the demise of a world-class electrophysiology laboratory" based there.[173] Squid giant axon diameters do not necessarily correlate with overall body size; those of the giant squid (Architeuthis dux) are only 0.137–0.21 mm (0.0054–0.0083 in) thick.[172]

Diagram showing the three major elements (red, green, and yellow) of the squid giant neuronal system. The arrows indicate the direction of transmission from the head ganglion towards the mantle. The funnel (light blue) is the site of rapid water expulsion following mantle contraction.

The squid giant synapse 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.[174] Many essential elements of how all chemical synapses function were first discovered by studying the squid giant synapse.[175]

Photophores

Taningia danae, a very large octopoteuthid squid, possesses "lemon-sized" yellow photophores at the tips of two of its arms, which are the largest known light-emitting organs in the animal kingdom.[176] 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.[177] 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 in 2015 can clearly be seen opening the lids to reveal its photophores.[178] 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.[179]


Reproductive organs

A dissected male specimen of Onykia ingens, showing an erect 67 cm (2.20 ft) penis approximating the combined length of the mantle, head, and arms

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.[180] 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.[181]

See also

Notes

  1. ^ The heaviest scientifically validated cephalopod specimen was a colossal squid (Mesonychoteuthis hamiltoni) weighing 495 kg (1,091 lb),[1] while hatchlings of Illex illecebrosus—some of the smallest known—have a mass of around 0.00015 g (5.3×10−6 oz).[2] The mass ratio between the two is .
    Comparing only adult females, the difference between the colossal squid and the pygmy squid Idiosepius thailandicus—which weighs 0.20 g (0.0071 oz) at maturity[3]—would be .
  2. ^ Wood & O'Dor (2000:93) elaborated on this mass estimate as follows:

    There are [...] no published weights of hatchling

    Waikiki Aquarium
    . The hatchling N. pompilius weighing 4.33 g [0.153 oz], with a maximum shell diameter of 26.25 mm [1.033 in], fit a highly significant correlation [...] between cubed shell diameter and weight, which indicates that a hatchling N. belauensis with a 30 mm [1.2 in] shell diameter [...] would weigh approximately 5.9 g [0.21 oz].

  3. ^ Norman et al. (2002:733) wrote: "The most extreme examples of sexual size dimorphism come from marine or parasitic taxa where females are difficult to locate (Ghiselin 1974)."
  4. ^ In particular, Scott Cassell mentioned a giant Humboldt squid he named 'Scar' (after the scars on its mantle), whose size he described thus:

    Scar is over seven feet [2.1 m] in length, larger than anyone has ever proven. His body was 3 feet [0.9 m] thick (He's too big to put my arms around him) and I estimated he weight [sic] between 230 and 250 pounds [100–110 kg].[75]

  5. armoured mammal Glyptodon
    and its relatives.
  6. footnote in Ellis, 1994a:145 he correctly stated the total length was "8 inches" [20 cm]). This mistake was repeated by Glaubrecht & Salcedo-Vargas (2004:67)
    , giving rise to the claim of an implausibly large psychroteuthid "with about three meter total length".
  7. ^
    type specimen in lateral aspect, from Kirk (1888). Note the extreme length of the feeding tentacles relative to the mantle and arms.Thomas William Kirk gave the following account of this specimen in his formal description
    of Architeuthis longimanus:

    [...] Early last month Mr. Smith, a local fisherman, brought to the

    [Colonial] Museum the beak and buccal-mass of a cuttle which had that morning been found lying on the "Big Beach" (Lyall Bay
    ), and he assured us that the creature measured sixty-two feet [18.9 m] in total length. I that afternoon proceeded to the spot and made a careful examination, took notes, measurements, and also obtained a sketch, which, although the terribly heavy rain and driving southerly wind rendered it impossible to do justice to the subject, will, I trust, convey to you some idea of the general outline of this most recently-arrived Devil-fish.

    Measurements showed that, although Mr. Smith was over the mark in giving the total length as 62 feet [18.9 m] (probably, not having a measure with him, he only stepped the distance), those figures were not so very far out; for, although the body was in all ways smaller than any of the hitherto-described New Zealand species, the enormous development of the very slight tentacular arms brought the total length up to 55 feet 2 inches [16.81 m], or more than half as long again as the largest species yet recorded from these seas.
    The length of the tentacular arms is not a very important character, as they are known to be capable of extension or retraction at the will of the animal, at least to a considerable extent.

    [...] This specimen was a female, and to this fact may be due some of the points in which it differs from previous occurrences; but yet they are so considerable that I have no doubt a new subgenus at least will have to be created for its reception. In the meantime I place it under Architeuthis, with the full knowledge, however, that it cannot possibly remain there permanently, the shape of the arms and the fins alone being sufficient to put it out of association with that genus. As soon as opportunity offers, I hope to make a further study and fully determine its affinities.[112]

    Kirk (1888:38) provides a table with a detailed breakdown of the specimen's various measurements. There is, however, a discrepancy between the total length of 684 in (17.37 m, or exactly 57 ft) given in the table—which agrees with the individual values of 71 in (1.80 m) for the mantle, 22 in (0.56 m) for the head, and 591 in (15.01 m) for the tentacles—and the total length of 55 ft 2 in (16.81 m) given by Kirk in the body of the article.

    Wood (1982:191) suggested that, due to the tentacles' highly retractile nature, the total length of 62 feet (18.9 m) originally reported by the fisherman "may have been correct at the time he found the squid", and that "[t]his probably also explains the discrepancy in Kirk's figures". Owing to its small mantle size, Wood (1982:191) estimated that "this specimen probably weighed less than 300 lb [140 kg]".

    O'Shea & Bolstad (2008) opined that the reported total length of 55 ft 2 in (16.81 m) "simply cannot be correct" and attributed it to either "imagination" or artificial lengthening of the tentacles. They added that a female giant squid with a mantle length of 71 in (180 cm) "measured post mortem and relaxed (by modern standards) today would have a total length of ≈32 feet [9.8 m]".

  8. ^ a b Kirk (1880:312) wrote of this specimen:

    On 23rd of May last, the Ven. Archdeacon Stock very kindly sent me word that three boys, named Edward R. Stock, and Frank and Walter Morrah, had that morning discovered, at Lyall Bay, what they took to be a very large cuttlefish, with arms several feet long. I lost no time in proceeding to the spot, determined, if possible, to carry home the entire specimen; but judge my surprise when, on reaching the bay, I saw an animal of the size represented in the drawing now before you.* Victor Hugo's account of his "pieuvre" was brought vividly to my mind, and I could not help thinking that a man would stand but a poor chance if he once got within the grasp of such a monster.

    My first step after spreading out the arms, was to make a rough sketch and very careful measurements. I then proceeded to extract the so-called skeleton, but found that some person or persons, who had visited the spot earlier than myself, had not been able to resist the temptation to try the temper of their knives upon its back, and had in consequence severed the cuttle-bone in various places. However, I was able, not only to procure all the pieces, but also the beak, tongue, and some of the suckers, only a few of which remained, the greater portion of them having been torn off, either in some fierce encounter, or during the rough weather which had prevailed for some days previously.
    The length of body from tip of

    tail
    to anterior margin of the mantle was 9 feet 2 inches [2.79 m] and 7 feet 3 inches [2.21 m] in circumference; the head from anterior margin of mantle to roots of arms 1-foot 11 inches [58 cm], making the total length of the body 11 feet 1 inch [3.38 m]. The head measured 4 feet [1.2 m] in circumference. The sessile arms measured 4 feet 3 inches [1.30 m] in length, and 11 inches [28 cm] in circumference; each of these arms bore thirty-six suckers, arranged in two equal rows (as shown by the scars), and measuring from to of an inch [20.6–6.4 mm] in diameter; every sucker was strengthened by a bony ring armed with from forty to sixty sharp incurved teeth. The tentacular arms had been torn off at the length of 6 feet 2 inches [1.88 m], which was probably less than half their original length.
    The fins were posterior, and were mere lateral expansions of the mantle, they did not extend over the back as in the case with Onychoteuthis, etc.; each measured 24 inches [61 cm] in length and 13 inches [33 cm] in width.

    The cuttle bone, when first extracted, measured 6 feet 3 inches [1.91 m] in length, and 11 inches [28 cm] in width, but has since shrunk considerably; it was broadly lanceolate, with a hollow conical apex 1 inch [28.6 mm] deep.

  9. ^ a b The Thimble Tickle specimen, which Addison Emery Verrill referred to as his specimen No. 18,[113] is often cited as the largest recorded giant squid, and has long been treated as such by Guinness.[114] The Thimble Tickle squid was found aground offshore, alive, on 2 November 1878, near Little Bay Copper Mine,
    Boston Traveller dated 30 January 1879, which was reproduced by Verrill (1880a:191–192)
    :

    On the 2d day of November last, Stephen Sherring, a fisherman residing in Thimble Tickle, not far from the locality where the other devil-fish [Verrill specimen No. 19; see Verrill, 1880a:192], was cast ashore, was out in a boat with two other men; not far from the shore they observed some bulky object, and, supposing it might be part of a wreck, they rowed toward it, and, to their horror, found themselves close to a huge fish, having large glassy eyes, which was making desperate efforts to escape, and churning the water into foam by the motion of its immense arms and tail. It was aground and the tide was ebbing. From the funnel at the back of its head it was ejecting large volumes of water, this being its method of moving backward, the force of the stream, by the reaction of the surrounding medium, driving it in the required direction. At times the water from the siphon was black as ink.

    Finding the monster partially disabled, the fishermen plucked up courage and ventured near enough to throw the grapnel of their boat, the sharp flukes of which, having barbed points, sunk into the soft body. To the grapnel they had attached a stout rope which they had carried ashore and tied to a tree, so as to prevent the fish from going out with the tide. It was a happy thought, for the devil fish found himself effectually moored to the shore. His struggles were terrific as he flung his ten arms about in dying agony. The fishermen took care to keep a respectful distance from the long tentacles, which ever and anon darted out like great tongues from the central mass. At length it became exhausted, and as the water receded it expired.

    The fishermen, alas! knowing no better, proceeded to convert it into dog's meat. It was a splendid specimen—the largest yet taken—the body measuring 20 feet [6.1 m] from the beak to the extremity of the tail. It was thus exactly double the size of the New York specimen [Verrill specimen No. 14; see Verrill, 1880a:189], and five feet [1.5 m] longer than the one taken by [fisherman William] Budgell [No. 19]. The circumference of the body is not stated, but one of the arms measured 35 feet [10.7 m]. This must have been a tentacle.

    Such is the fame of the Thimble Tickle specimen that a Giant Squid Interpretation Centre and a "life-sized", 55-foot (17 m) sculpture have been built near the site of its capture.[115] The sculpture appeared on a Canadian postage stamp issued in 2011.[116]

  10. lower rostral length
    (LRL) of the beak, and total length (TL) from DML:


    (all values in mm)[123]
    (all values in m)[124]
    (all values in m)[124]
    (all values in m)[125]
  11. ^ Aldrich restated this belief in "Monsters of the Deep", the second episode of the 1980 television series Arthur C. Clarke's Mysterious World: "I believe the giant squid reach an approximate maximum size of something like one hundred and fifty feet [46 m]".[135] Richard Ellis, apparently unaware of Aldrich's similar statements in print, commented: "It is difficult to imagine why Aldrich would have made such an irresponsible statement, unless it had to do with being on camera".[136] Arthur C. Clarke himself once remarked: "it would be strange indeed if the world's biggest squid had been among the very few cast ashore to be examined and measured by naturalists. There may well be specimens more than a hundred feet [30 m] in length."[137]
  12. ^ An example from the May 2000 issue of Diver magazine reads: "The generally accepted record was of awesome proportions, weighing 272kg and with an arm span of 9.6m."[149]
  13. Mesonychoteuthis which, judging by its width, must have come from a cranchid [sic] measuring at least 5 m [16 ft] in mantle length." The same information is summarised by Bright (1989:146)
    .
  14. ^
    Bulletin of the United States Fish Commission (1881), showing the proportionately short length of the arms and tentaclesEllis (1998a:148–149)
    wrote of this specimen:

    The Russian vessel Novoulianovsk, working in the

    Mesonychoteuthis hamiltoni
    (of the same family)." Only an arm and a tentacle were collected, but they were so large (the arm was 40 cm long [15.6 inches] and the tentacle 115 cm [45.5 in]) that Nesis was able to estimate the mantle length at 265 to 275 cm (8.69 to 9.02 ft), and the total length at over 4 meters (more than 13 feet). "Because of its narrow body," wrote Nesis, "we conclude that its mass is consistently lower than that of the other large squids."

    Roper & Jereb (2010c:165) questioned the validity of this record, writing: "this is considered a doubtful record that might refer to total length; probably the maximum mantle length is less than 400 to 500 mm". But Steve O'Shea commented:

    The late, great Kir Nesis was not one to exaggerate, and must have had very good reason to cite a possible mantle length of 2.7m [8.9 ft] for Galiteuthis phyllura. Not only would such a monstrous mantle render this the 'largest species of Galiteuthis', but it would give the species a mantle that was considerably longer than that of Architeuthis, and marginally longer (0.2m [0.66 ft]) than the submature Colossal Squid (Mesonychoteuthis) we reported last year [in 2003].
    What amazes me is that the adult has never made the press (that I am aware of). Even if Galiteuthis lacks hooks on the arms it would still be a most frightening squid to bump into in the abyss. (O'Shea, 2004b)

  15. ^
    A. cornutus
    ).
  16. ^ This record is based on a shell collected in 2001 from the Timor Sea off Indonesia, which was sold in 2003 as a specimen of N. repertus with a diameter of 268 mm (10.6 in). It was subsequently found to measure only around 243 mm (9.6 in) and the discrepancy was put down to an encoding mistake ([Anonymous], 2003a). Another specimen from the same locality, sold around the same time, was claimed to measure 255 mm (10.0 in) ([Anonymous], 2003b).
  17. ^ There are two places which bear or have borne the name Joachimsthal: Jáchymov, Czech Republic and Joachimsthal, Brandenburg, Germany. The citation quotes an unpublished report, and it is unclear which one it is referring to. If the report is later than 1945, when the official name of the Czech town was changed, it is most likely the place in Germany.

References

Short citations

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  5. ^ a b c Nilsson et al., 2012:683
  6. ^ Smith et al., 2016
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  8. ^ a b c Vermeij, 2016
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  11. ^ Salvador & Tomotani, 2014
  12. ^ Ley, 1941
  13. ^ Lee, 1883; Ellis, 1994b
  14. ^ see Garcin & Raynal, 2011; Barrère, 2017
  15. ^ Guerra et al., 2011
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  17. ^ Landman & Ellis, 1998; Ablett, 2012
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  20. ^ Roper & Voss, 1983:55
  21. ^ see Arkhipkin et al., 2015
  22. ^ a b c O'Shea & Bolstad, 2008
  23. ^ Roper & Young, 1972:205
  24. ^ Clarke, 1996:1105; O'Shea & Bolstad, 2008
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  26. ^ Clarke, 1986:11
  27. ^ Zeidberg, 2004:4195; Phillips, 2004:ii
  28. ^ Nabhitabhata, 1998:32
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  31. ^ Grulke, 2014:105
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  46. ^ Lovis, 2011
  47. ^ [Anonymous], N.d.
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  78. ^ Guerra & Segonzac, 2014:65
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  87. ^ Carnall, 2017
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  90. ^ Beer, 2015
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  93. ^ Flower, 1955:329
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  95. ^ Grulke, 2014:124
  96. ^
    ISSN 0567-7920
    .
  97. ^ .
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  100. ^ Robson, 1933:681; see for example Mitsukuri & Ikeda, 1895; Meek & Goddard, 1926; Clarke & Robson, 1929; Phillips, 1933; Croker, 1934; Rees, 1950; Smith, 1963; Nesis, 1970
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  102. ^ Poppe & Goto, 1993
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  104. ^ [Anonymous], 2007; Kubodera, 2010:38
  105. ^ [Anonymous], 2013; [NHK], 2013c
  106. ^ Baird, 2002
  107. ^ [Anonymous], 2002a; O'Shea, 2003d
  108. ^ e.g. Guerra et al., 2018
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  110. ^ O'Shea & Bolstad, 2008; Dery, 2013; Yong, 2015
  111. ^ see Hansford, 2009
  112. ^ Kirk, 1888:35–36
  113. ^ a b Verrill, 1880a:191; Verrill, 1880b:285
  114. ^ see Wood, 1982:189; Carwardine, 1995:240; Glenday, 2014:62
  115. ^ Hickey, 2009
  116. ^ Hickey, 2010; [Anonymous], N.d.
  117. ^ Paxton, 2016a:86
  118. ^ Murray, 1874:121
  119. ^ a b c d Romanov et al., 2017
  120. ^ Paxton, 2016a:83
  121. ^ see Murray, 1874; Verrill, 1875a; Verrill, 1875b
  122. ^ see Roeleveld, 2000; Cherel, 2003; Romanov et al., 2017
  123. ^ Roeleveld, 2000:185
  124. ^ a b Paxton, 2016a:85
  125. ^ McClain et al., 2015:Table 2
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  128. ^ Wood, 1982:193
  129. ^ Roper & Boss, 1982:99; Wood, 1982:192; Haszprunar & Wanninger, 2012:R510
  130. ^ Ellis, 1998a:143
  131. ^ see Ellis, 1998a:142
  132. ^ Matthews, 1938
  133. ^ Ley, 1959:210
  134. ^ a b Aldrich, 1980:59
  135. ^ Ellis, 1998a:6–7
  136. ^ Ellis, 1998a:7
  137. ^ Ellis, 1998a:6
  138. ^ Ellis, 1998a:142
  139. ^ see Feldman, 1999 for more on this specimen
  140. ^ O'Shea, 2003a; Roper & Jereb, 2010a:121
  141. ^ Alexander, 1998:1233
  142. ^ a b Ellis, 1998a:106
  143. ^ MacGinitie & MacGinitie, 1949
  144. ^ MacGinitie & MacGinitie, 1968; Wood, 1982:190
  145. ^ Heuvelmans, 1958
  146. ^ Ellis, 1998a:107
  147. ^ Dall, 1885:432
  148. ^ Newman, 1994:66
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  154. ^ The Azorean Loligo forbesi (Cephalopoda: Loliginidae) in captivity: transport, handling, maintenance, tagging and survival
  155. ^ Body size and fin length as determinants in the geographic distribution of Loliginid squids
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  157. ^ .
  158. .
  159. .
  160. .
  161. .
  162. ^ Kitakyushu Museum of Natural History & Human History (2015-03-05). "史上最大級のイカ類とタコ類の化石発見".
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  165. ^ Farquhar, 2014; [Te Papa], 2014
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  167. ^ Motani et al., 1999; Humphries & Ruxton, 2002
  168. ^ Nilsson et al., 2012:687
  169. ^ Schmitz et al., 2013a:45
  170. ^ Ellis, 1996:177; [Anonymous], 2005a; though see Young et al., 2015
  171. ^ Partridge, 2012
  172. ^ a b Adelman & Gilbert, 1990:102
  173. ^ Scully, 2008
  174. ^ Arata, 1954; Murata, 1988; Maciá et al., 2004; Muramatsu et al., 2013; O'Dor et al., 2013
  175. ^ see Llinás, 1999
  176. ^ Ellis, 1998a:149; Barrat, 2015
  177. ^ see Kubodera et al., 2006
  178. ^ see Barrat, 2015
  179. ^ Kubodera et al., 2006:1033
  180. ^ Arkhipkin & Laptikhovsky, 2010:299; Walker, 2010
  181. ^ Arkhipkin & Laptikhovsky, 2010:300

Full citations

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