page_title: Cephalopod size
section_title: Giant squid (Architeuthis dux)
hierarchical_section_title: Cephalopod size / Maximum size / Scientifically validated records / Giant squid (Architeuthis dux)
caption_attribution_description: Giant squid from Logy Bay, Newfoundland in bathtub, November/December, 1873.
context_page_description: Cephalopods vary enormously in size. The smallest are only about 1 centimetre long and weigh less than 1 gram at maturity, while the largest—the giant and colossal squids—can exceed 10 metres in length and weigh close to half a tonne, making them the largest living invertebrates. Living species range in mass more than three-billion-fold, or across nine orders of magnitude, from the lightest hatchlings to the heaviest adults. Certain cephalopod species are also noted for having individual body parts of exceptional size. The giant and colossal squids, for example, have the largest known eyes among living animals.
  Cephalopods were at one time the largest of all organisms on Earth, and numerous species of comparable size to the largest present day squids are known from the fossil record, including enormous examples of ammonoids, belemnoids, nautiloids, orthoceratoids, teuthids, and vampyromorphids. In terms of mass, the largest of all known cephalopods were likely the giant shelled ammonoids and endocerid nautiloids, though perhaps still second to the largest living cephalopods when considering tissue mass alone.
  Giant cephalopods have fascinated humankind since time immemorial.
context_section_description: The maximum size of the giant squid (Architeuthis dux) has long been a subject of both popular debate and academic inquiry (Ellis, 1998b; Paxton, 2016a; Bittel, 2016; Romanov et al., 2017). 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 (Paxton, 2016a). This number has since increased substantially, with 57 specimens recorded from Japanese waters during an exceptional 15-month period between 2014 and 2015 (Kubodera et al., 2016).
  Based on a 40-year data set of more than 50 giant squid specimens, Roper & Shea (2013:114) suggest an average total length at maturity of 11 m (36 ft) and a "rarely encountered maximum length" of 14–15 m (46–49 ft). Of the nearly 100 specimens examined by Clyde 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 (43 ft) for females based on the examination of more than 130 specimens, measured post mortem and relaxed, as well as beaks recovered from sperm whales (which do not exceed the size of those found in the largest complete specimens). Steve O'Shea estimated the maximum total length for males at 10 m (33 ft) (O'Shea, 2003a). Older records of 18 m (59 ft) 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). Charles G. M. Paxton performed a statistical analysis using literature records of giant squid specimens and concluded that "squid with a conservative TL of 20 m [66 ft] would seem likely based on current data" (Paxton, 2016a, b), but the study has been heavily criticised by experts in the field (Greshko, 2016). O'Shea has stated that, given the available evidence, the highest 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" (Bittel, 2016). O'Shea contends that Paxton's estimates are skewed because his data set included unreliable (and exaggerated) records from the nineteenth century. Paxton has responded that even when these questionable records are excluded the analysis gives "a maximum length of just over 20 metres with a 99.9% prediction interval" (Bittel, 2016).
  O'Shea & Bolstad (2008) give a maximum mantle length of 225 cm (7.38 ft) 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), though there are recent scientific records of specimens that slightly exceed this size (such as the 240 cm [7.9 ft] ML 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 (16 ft) ML can be found in older literature (Roper & Jereb, 2010a:121). Paxton (2016a) accepts a maximum recorded ML of 279 cm (9.15 ft), 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 (6.2 ft) long (Greshko, 2016).
  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 (Greshko, 2016).
  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 recov
caption: A giant squid from Newfoundland, draped over Reverend Moses Harvey's sponge bath, 1873. The extremely long feeding tentacles of the giant squid make it the longest known cephalopod, past or present.
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