Fig. 1.Basic squid morphology|
Authored by Dr. Steve O'Shea and Dr. Kat Bolstad
Steve and Kat are members of the TONMO staff. You can communicate with them both in our Cephalopod Science forums.
INTRODUCTION TO FACT SHEETSTo ensure accurate reporting of these squid species, the following brief notes have been prepared. First, a simplified account of squid morphology (Fig. 1), where we detail the differences between squid and octopus; second, an introduction to size and how it has been measured (and misreported); and third, an introduction to the two species that you will be hearing a lot about: Colossal Squid (Mesonychoteuthis hamiltoni) and Giant Squid (Architeuthis dux).
We already have online an introduction to octopus and squid anatomy in our article, Deep-Sea Cephalopods: An Introduction and Overview, so will not unnecessarily duplicate that information. For the sake of this article we will focus on the absolute basics of cephalopod anatomy, and some frequently cited measures, particularly Mantle Length (ML), Standard Length (SL), and Total length (TL).
1. Introduction to squid anatomy: Basic squid and octopus facts
A basic squid has:
A basic octopus has:
Some squid naturally lose the tentacles in post-larval stages, so that the adult possesses 8 arms only; some squid can have more than 2 fins. Some octopuses (9 species in New Zealand waters) possess two well-developed fins; these 9 species also have a well-developed pen (like a cuttlebone) in their mantle, and are considered rather primitive, commonly referred to as 'Dumbo Octopuses'.
The only universal distinction between a squid and an octopus is that the suckers of squid are armed with hooks or sucker rings (or a combination of the two), while octopus have simple suckers without secondary armature (Fig. 5). It is the squids' hooks and rings that have enthralled the public most. You will find additional information on squid and octopus in our Guide to Frequently Used Characters, Character States and Measures.
With this basic introduction to octopus and squid anatomy aside, we can move on to the real purpose of this fact sheet. The Giant and Colossal Squid Fact Sheet.
Fig. 2: tentacle club of Architeuthis,|
showing circular-saw-like sucker rings.
Fig. 3: tentacle club of Mesonychoteuthis,
with swiveling hooks.
Fig. 4: Profile of Mesonychoteuthis tentacle club, showing hooks.
Fig. 5: Suckers of Haliphron atlanticus,|
the giant gelatinous octopus (the world's
largest species of octopus), lacking
What we know about Giant Squid (Architeuthis dux) (Figs 6–9):
Fig. 8: size comparison of Architeuthis |
and Mesonychoteuthis, based
on accounts of maximum mantle length.
Fig. 9: size comparison of mature|
Architeuthis (right) beaks recovered
from sperm whale stomachs.
There is also a tremendous body of scientific literature available for this species.
The juvenile was caught and filmed live by Dr Steve O'Shea in 2001; unfortunately all died before they could be grown in captivity. The adult was photographed live off Japan in a series of stills by Dr Tsunemi Kubodera in September 2004; the adult was subsequently filmed live at the surface off Japan in December 2006, also by Dr Tsunemi Kubodera.
Architeuthis is frequently misreported to attain a total length of 20 metres (~65 feet). However, the largest specimen known washed ashore on a New Zealand beach, Lyall Bay (Wellington) in the winter of 1887. It was a female and "in all ways smaller than any of the hitherto-described New Zealand species", according to Kirk (1887), the gentleman who described this very specimen. Apparently it measured 55 feet 2 inches in total length (16.8m), but this simply cannot be correct, and this length almost certainly is a product of imagination or lengthening (stretching like rubber bands) of the very slight tentacular arms, as it mantle was only 71 inches long (1.8m). We know that it was not measured with a conventional tape, but was paced, as Kirk says so in his publication. A comparable-sized female (ML 1.8m) measured post mortem and relaxed (by modern standards) today would have a total length of ~32 feet (9.8m).
Mantle length (as opposed to total length) is the standard measure in cephalopods. Of more than 130 Architeuthis specimens that the authors have examined, none has attained a mantle exceeding 2.25m (7.4 feet), or total length of 13m (42 feet).
Standard Length (SL) is the length of a squid excluding the tentacles; in Architeuthis this measure very rarely exceeds 5m. The rest of the animal's length, to a total length of 13m, is made up of the two long tentacles. Of more than 130 specimens that we have examined, none has exceeded these figures (Fig. 7).
Architeuthis beaks recovered from the stomachs of sperm whales are smaller than or of comparable size to Architeuthis beaks recovered from specimens trawled in New Zealand waters. Therefore, since we believe sperm whales capable of catching even the largest giant squid, no evidence exists for recognising larger specimens than those that are currently known. Moreover, it is most likely that a single species, Architeuthis dux, exists worldwide, so 'larger species' of Architeuthis do not occur. Accordingly, to perpetuate myths of Architeuthis to 20 metre lengths (60 feet) and weights of up to 1000kg (a ton, or 2205lbs) is a disservice to science.
Mesonychoteuthis hamiltoni Robson, 1925 (Figs 1, 3, 4, 8, 9) Vernacular: Colossal Squid; Giant Cranch Squid
On April 1, 2003 the popular press was first alerted to the Colossal Squid, a.k.a. Mesonychoteuthis hamiltoni, although this species has been known to the scientific community since 1925, after it was described from two arm (brachial) crowns recovered from sperm whale stomachs (Robson 1925). We have located 11 further reports in which adult and subadult specimens have been described, and are aware of at least 7 further, similarly sized specimens that have yet to be reported. Juveniles of this species are not uncommon from surface waters to ~1000m depth.
Otherwise this species doesn't really differ from any other cranchiid squid (Family Cranchiidae) in any remarkable manner, with the exception of its size.
The 'colossal' cranchiid squid Mesonychoteuthis hamiltoni is thought to be the largest of all Recent cephalopods. However, due to lack of material, and the fragmentary, partially digested or juvenile nature of almost every previously reported specimen, the biology and morphology of this species have remained poorly known.
Mesonychoteuthis hamiltoni is actually a quite-well studied species, with 11 specimens above juvenile size (arbitrarily taken as 90mm ML), including the two Syntypes, having been reported since 1925. McSweeny (1970) provides a complete description of the juvenile of this species. Klumov & Yukhov (1975, in Russian) describe several (possibly 5) specimens of ML 390–1550mm, and offer a detailed account of hook, radular, beak, gladius, photophore, arm, tentacular club, and spermatophore morphology. Voss (1980) describes a subadult female of ML 1.25m and refers to ‘several large partial specimens' (brachial crowns) in collections of the United States National Museum, Smithsonian Institution. Rodhouse & Clarke (1985) report a further specimen, ML 1.05m, trawled at a depth of 2000-2200m. Finally, Lu & Williams (1994) briefly report two specimens (one male, 107mm ML, and one female, 118mm ML), from a midwater trawl in Prydz Bay, Antarctica. Several additional authors have touched on various aspects of the species' anatomy in other papers: Clarke (1962, 1980) describes and illustrates the beaks; Engeser & Clarke (1988) illustrate both arm and tentacular hooks; Young (1984) illustrates the statocyst; Herring et al. (2002) further describe the ocular photophores on the specimen reported by Rodhouse & Clarke (1985); and Xavier et al. (2003) report a single tentacle from M. hamiltoni recovered from a longline hook off South Georgia. Clarke (1966) refers to 'several complete specimens... collected from sperm whale stomachs in the Antarctic,' the largest of which had a ML of 2–2.25m, but it is not certain whether either of these specimens has been reported on or described further; the location of these specimens also is unknown.
Further information has been gleaned from gut-content analysis of its predators, primarily sperm whales, wandering albatross, Patagonian and Antarctic Toothfish, and sleeper sharks. Even the first two described specimens of this species were recovered from the stomach of a sperm whale, although they are undetermined sex and are in poor condition.
Based on all sources, M. hamiltoni appears to be abundant in the Antarctic, and important in the diets of apex predators such as the sperm whale (76–77% of male whale diet (Clarke 1980, Rodhouse & Clarke 1985) and sleeper shark (52% by weight (Cherel & Duhamel 2004).
This species attains the greatest weight, but not necessarily greatest length of all squid species, and is known to attain a mantle length of at least 2.5m. Should accounts relayed to us be correct, the largest specimen that we will be defrosting at the end of April 2008 has a ML of 4m.
In the absence of numerous specimens taken from a variety of localities (with the exception of paralarvae (relatively tiny juveniles), known to have circumpolar Antarctic distribution (Voss 1980, Nesis 2003)), the life history and zoogeography of M. hamiltoni must be inferred from more indirect sources. Although predators are useful in providing some information on large squid species (perhaps our best source at present), deriving information on the geographic distribution of prey species solely from gut content specimens is risky (O'Shea 2007). Certain predators of M. hamiltoni are known to undertake extensive migrations; wandering albatross range in excess of 1200 km from their nest sites on average in search of prey (Jouventin & Weimerskirch 1990) and sperm whales are also known to migrate thousands of kilometres.
Popular press has focussed on the size of this squid, and there has been considerable debate at an academic level as to whether the Colossal Squid is actually the largest squid, because the Giant Squid, Architeuthis dux, attains a greater total length.
There are several ways in which squid are measured (and in which their size or length may be exaggerated): Total Length relaxed (post mortem); Total Length when the animal is live (and outstretched); Standard Length, the length of the animal minus its two long tentacles; estimated length (the one that got away); weight; and, most inappropriately, length relative to a London double-decker bus.
As this Colossal Squid is likely to make international press, information often is misquoted. For your ease we've provided a few conversions below:
1 foot = 0.3048 metres (alternatively, 1 metre = 3.2808 feet)
1 kilogram = 2.2 pounds (alternatively, 1 pound = 0.5kg)
Therefore, a 2.5m ML Colossal Squid of 300kg is equivalent to an 8.202 foot ML Colossal Squid weighing 660 lbs; the 495kg Colossal Squid to be defrosted at the end of April 2008 weighs in at a colossal 1089 lbs.
The specimen reported on April 1, 2003 was a submature female of ML 2.5 m; despite it being extensively damaged it weighed ~300kg, and had a Total Length of 5.4m. At the time it was both the heaviest squid known to science, and squid with the longest mantle (reliable measures). The lower beak of this particular specimen had a rostral length (LRL) of 38mm. Lower beaks of Mesonychoteuthis are known to 49mm LRL, so we know that this species grows considerably larger. In late April we actually will be examining at least four Mesonychoteuthis: the 495kg specimen; a second, evidently extensively damaged specimen weighing ~150kg; and several considerably smaller specimens more recently taken in Antarctic waters.
Just how big does Mesonychoteuthis get? Well, we don't know; the largest LRL currently known measures 49mm. The first thing that we will do when this specimen is completely defrosted is measure LRL, and should this be less than 49mm we will know that Mesonychoteuthis gets even larger and heavier than the specimen we have.
Next we will determine the sex of the specimens (as a rule female squid attain a larger size than males), and their state of reproductive maturity will be appraised. Both sex and an indication of maturity provide insights into the realistic maximum size of a species.
New Zealand reports based on analysis of stomach contents of long-distance foraging marine predators
Beaks attributed to this species have previously been encountered in stomachs of sperm whales caught in or proximal to northernmost eastern and western New Zealand waters (Clarke & MacLeod 1982), from one stranded specimen on Paekakariki Beach (Clarke & Roper 1998), and otherwise from numerous stranded specimens from beaches around New Zealand (Gomez-Villota 2007). They are also reported from wandering albatross chick regurgitations from Antipodes Islands (Imber 1992) and immediately south of New Zealand (Australian waters), Macquarie Island (Imber 1978, 1992). However, despite these five citations from local waters, and a sixth, as yet unpublished Macquarie Island record (an actual specimen trawled from 1143m), none of them confirms that the species occurs here, as wandering albatross, Diomedia exulans, average in excess of 1200 km from the nest site in search of prey (Jouventin & Weimerskirch 1990), and sperm whales, especially large males, undertake extensive migrations (O'Shea 1997). Mesonychoteuthis beaks have been reported from sperm whale stomachs captured off California (Fiscus et al. 1989), so the whales obviously retain some beaks in the stomach for considerable periods of time.
The occurrence of Mesonychoteuthis beaks in stomachs of female and small male sperm whales is intriguing, as these predators normally occur north of 40°S, while the squid are primarily reported from south of 40°S. Therefore Mesonychoteuthis, presently known from Antarctic waters, could extend as far north as 40°S, with the Subtropical Convergence delimiting the species' northern distribution (Clarke 1980). If true this would place this species in New Zealand waters, extending from a latitude equivalent to Christchurch through to the Chatham Islands.
In the southern hemisphere, female and young male sperm whales (to ~39 feet in length) are not normally found in latitudes higher than 40°S, while large males occur in Antarctic waters; large bulls must migrate from the lower-latitude breeding areas into colder Antarctic waters (the smallest male reported from the Antarctic was 35 feet in length (Clarke 1972). The male stranded on Mahia Peninsula 28/11/2002 was 13 metres (42 feet) in length, and its stomach contained 7 lower Mesonychoteuthis beaks. It had probably only recently migrated back from the Antarctic, and had likely made few migrations to the region in its life.
Closest record (unreported): between Macquarie Island and Stewart Island, ~140 n. miles south of New Zealand waters, an immature female, ML (when fresh) 0.9m (coordinates 53°49.30'S, 159°04.44'E), from 1143m.
Reproduction: Unknown; mature male unknown.
Cherel, Y.; Duhamel, G. 2004. Antarctic jaws: cephalopod prey of sharks in the Kerguelen waters. Deep-Sea Research I 51: 17–31.
Clarke, M.R. 1962. The identification of cephalopod "beaks" and the relationship between beak size and total body weight. Bulletin of the British Museum (Natural History), Zoology 8(10): 419-480.
Clarke, M. 1966. A review of the systematics and ecology of oceanic squids. Advances in Marine Biology 4: 91–300.
Clarke, M.R. 1980. Cephalopoda in the diet of sperm whales of the southern hemisphere and their bearing on sperm whale biology. Discovery Reports 37: 324 pp.
Clarke, M.R.; MacLeod, N. 1982. Cephalopod remains from the stomachs of sperm whales caught in the Tasman Sea. Memoirs of the National Museum Victoria 43: 25-42.
Clarke, M.R.; Roper, C.F.E. 1998. Cephalopods represented by beaks in the stomach of a sperm whale stranded at Paekakariki, North Island, New Zealand. South African Journal of Marine Science 20: 129-133.
Engeser, T.S.; Clarke, M.R. 1988. Cephalopod hooks, both recent and fossil. The Mollusca 12: 133–150.
Fiscus, C.H.; Rice, D.W.; Wolman, A.A. 1989. Cephalopods from the stomachs of sperm whales taken off California. NOAA Technical Report NMFS 83: 1-12.
Gomez-Villota F 2007. Sperm whale diet in New Zealand. Unpublished MAppSc thesis. Division of Applied Sciences, Auckland University of Technology, Auckland, New Zealand. 221 p.
Herring, P.J.; Dilly, P.N.; Cope, C. 2002. The photophores of the squid family Cranchiidae (Cephalopoda: Oegopsida). Journal of Zoology 258: 73-90.
Imber, M.J. 1978. The squid families Cranchiidae and Gonatidae (Cephalopoda: Teuthoidea) in the New Zealand region. New Zealand Journal of Zoology 5: 445-484.
Imber, M.J. 1992. Cephalopods eaten by wandering albatrosses (Diomedia exulans L.) breeding at six circumpolar localities. Journal of the Royal Society of New Zealand 22(4): 243-263.
Kirk, T.W. 1887. Brief description of a new species of large decapod (Architeuthis longimanus) . Transactions and Proceedings of the New Zealand Institute 20: 34–39 + 3 Pls.
Klumov, S.K.; Yukhov, V.L. 1975. Mesonychoteuthis hamiltoni Robson, 1925 and its importance in the feeding of sperm whales in the Antarctic. Antarctica 14: 159–189. [Russian]
Lu, C.C.; Williams, R. 1994. Contribution to the biology of squid in the Prydz Bay region, Antarctica. Antarctic Science 6(2): 223–229.
McSweeny, E. 1970. Description of the juvenile form of the Antarctic squid Mesonychoteuthis hamiltoni Robson. Malacologia 10(2): 323–332.
Nesis, K.N. 2003. Distribution of Recent Cephalopoda and implications for Plio-Pleistocene events. Berliner Paläobiologische Abhandlungen 3: 199-224.
O'Shea, S. 1997. Status of three Octopoda recorded from New Zealand, based on beaks recovered from long-distance foraging marine predators. New Zealand Journal of Zoology 24: 265–266.
Robson, G.C. 1925. On Mesonychoteuthis, a new genus of oegopsid Cephalopoda. Annals and Magazine of Natural History (series 9) 16: 272 –277, 2 figures.
Rodhouse, P.G.; Clarke, M.R. 1985. Growth and distribution of young Mesonychoteuthis hamiltoni Robson (Mollusca: Cephalopoda): an Antarctic squid. Vie Milieu 35(3/4): 223-230.
Voss, N.A. 1980. A generic revision of the Cranchiidae (Cephalopoda: Oegopsida). Bulletin of Marine Science 30(2): 365-412.
Xavier, J.C.; Croxall, J.P.; Trathan, P.N.; Rodhouse, P.G. 2003. Inter-annual variation in the cephalopod component of the diet of the wandering albatross, Diomedea exulans, breeding at Bird Island, South Georgia. Marine Biology 142: 611–622.
Young, J.Z. 1984. The statocysts of cranchiid squids (Cephalopoda). Journal of Zoology 203: 1–21.
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-- Last updated: April 6, 2008