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Giant squid beaks: Implications for systematics

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Abstract

The systematic position of the giant squid Architeuthis remains unresolved but comparison of beak morphometrics is an approach that has not been attempted before. Additional data for the relationship between mantle length (ML) and lower beak rostral length (LRL) suggest that Architeuthis sp. in the North Atlantic, South Africa and New Zealand are parts of the same asymptotic relationship. Comparison of beak dimensions of Architeuthis from the North Atlantic, South Africa and New Zealand with those of two distinct species of Todarodes, from the Mediterranean and southern Africa, indicate that there may be only one species of Architeuthis in these three regions. No consistent morphological evidence has yet been found to indicate more than one species of Architeuthis in the Atlantic or in the southern hemisphere.

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... Data of lower rostral length and mantle length of giant squids caught in the Southern Hemisphere were pooled in order to determine their relationship. The data set included 12 individuals from South Africa (Roeleveld, 2000), 10 from New Zealand (Förch, 1998) and the two indviduals described here together with that reported by Ré et al. (1998) from Argentina ( Figure 6). ...
... Ré et al. (1998) data (!), New Zealand data (") from Förch (1998) and South African data ( +) from Roeleveld (2000). Ré et al. (1998), datos de Nueva Zelanda (") tomados de Förch (1998) y datos de Sudáfrica ( +) tomados de Roeleveld (2000). ...
... High variability, even in hard structures, already reported by Förch (1998) and Roeleveld (2000), is confirmed not only among different animals but also between paired structures of the same animal. That is the case of the statoliths of specimen 2, which differed in their total length, relative size of the lateral dome and rostrum and number of lobes in the lateral dome. ...
... Dorsal mantle length (DML) and total length (TL) was reconstructed using the rostral length of lower beaks (Fig. 1A), using equations of Roeleveld (2000) and Paxton (2016), as shown in Table 1. Equations are shown below for Roeleveld model (Eq. 1) and Paxton models for DML (Eq. ...
... I = inmature; F = female. Reconstructed body measurements (*) from rostrum length of lower jaws using equations from Roeleveld (2000) and Paxton (2016). DML = dorsal mantle length; TL = total length; GR = estimate of growth rate (mm DML d −1 ). ...
... Statolith count of individual ID8 was 520 increments, and comparing with RSS reading 1 of the specimen (579 increments) indicates around 2 mo of difference, with around 10% fewer increments in the statolith. Relationships between the number of increments in RSS (an approximation of age in days) and beak measurements in both upper and lower jaws are shown in Figure 3. Reconstructed DML from the equation of Roeleveld (2000) had more similarity to those estimated during sampling of the specimen in the lab (when available). For this reason, this equation was used for reconstructed DML and this assessed its relationship with the number of increments in RSS. ...
Article
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The giant squid Architeuthis dux Steenstrup, 1857 is one of the largest and most enigmatic marine species. Its age estimation remains controversial with many estimates of maximum age ranging from 1 to 14 years. Successful results regarding the study of aging in cephalopod beaks for some octopod and oegopsid squids support using these structures for age estimation. We analyzed the beaks of 10 individuals, caught between 1995 and 2006, with reconstructed dorsal mantle lengths (DMLs) between 823 and 1418 mm. The beaks were measured and weighed and their microstructure was analyzed in three ways: in the rostrum area (rostrum sagittal sections-RSS) for both upper and lower jaws, and the inner lateral wall surfaces (LWS) and crest (CS) for upper jaws. A constant sequence of increments was observed along the RSS, indicating that the use of lower jaws is more feasible due to the higher erosion and tighter packing of increments of upper jaws. The statolith of one individual was analyzed, resulting in 520 increments (579 increments from RSS of its lower jaw). Assuming daily deposition, the age estimations in RSS between 411 and 674 days suggest rapid growth of A. dux, averaging 1.97±0.45 mm DML d ⁻¹ . When maximum ages were estimated by applying these results to the largest measured specimens in the literature (e.g., 2400 mm DML) an age of ~3 years was obtained. Analysis over a greater size range of individuals would allow more accurate age estimations of this emblematic squid.
... The lower rostral length was used as a predictor of the DML based on Roeleveld (2000) (1) and Paxton (2016) (2) equations: ...
... The dorsal mantle length of A. dux reported here (3060 mm, estimated from equation (1)) exceeds the DML of the other Mascarene Islands specimens (Staub, 1993;Cherel, 2003) (Table 1). Cherel (2003) also estimated DML from Roeleveld's (2000) equation (1); however, direct size comparisons are less reliable with the specimen from Staub (1993) due to the ambiguous information on how measurements were taken. Comparisons of the giant squid proportions with human personages, depicted next to the specimen in photographs, suggest that Staub (1993) probably measured standard length (i.e. the length from the posterior end of the mantle to the tip of the arms) which was referred to as a 'body measurement' ('son corps mesurait') in the original paper. ...
... In this study, the A. dux DML is 28% longer than the longest one reported by Cherel (2003) from the Kerguelen Archipelago (Table 1). On a global scale, our DML estimates based on Roeleveld's (2000) equation exceeds 'longest reliably measured' DML (2794 mm) (Kirk, 1880in Paxton, 2016 reported to date, and may represent the largest giant squid ever discovered. However, Paxton (2016) suggested that Roeleveld's (2000) equation overestimates DML, at least for large individuals. ...
Article
A freshly dead individual of the giant squid Architeuthis dux, presumably mutilated by a predator of bigger or comparable size, is reported from the south-western Indian Ocean in proximity to Reunion Island. The species was identified from body and beak morphology and validated genetically. The dorsal mantle length (DML) estimated from beak measurements (lower rostral length, LRL) varied between 2153 and 3060 mm depending on the allometric equation used. The Architeuthis dux individual described here is the biggest giant squid ever reported for the region.
... Their mouth is located in the middle of the circle formed by the arms and contains a pair of powerful chitinous mandibles called a "beak" due to their resemblance to a parrot's beak. Beaks are often cited in taxonomy, as a genus and sometimes even a species can be identified by its beak alone (Ogden et al., 1998;Roeleveld, 2000). Inside the mouth lies the radula, a rasping tongueshaped structure equipped with many rows of small chitinous teeth, giving it the capacity to pluck small portions of food. ...
... Architeuthis, the single genus of the family Architeuthidae, has about 20 species, many precariously described, usually based only on tentacle fragments (Figure 10), beaks ( Figure 11) or other body parts (Clarke, 1966(Clarke, , 1968Roper, Boss, 1982;Roeleveld, 2000). Until the 1940s, it was common practice to describe a new species whenever a new fragment was found, as Steenstrup, Verrill and others had done. ...
... Until the 1940s, it was common practice to describe a new species whenever a new fragment was found, as Steenstrup, Verrill and others had done. This is why the descriptions were never accompanied by clear diagnoses to distinguish among the many species (Clarke, 1966;Roper, Boss, 1982;Roeleveld, 2000). Thus, the family's taxonomy remains messy to this day, in large part due to the scarcity of well-preserved material and the logistical difficulty of conducting a comparative study with such huge animals. ...
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Séculos atrás, marinheiros se amedrontavam com histórias do Kraken, um terrível monstro marinho capaz de afundar embarcações e devorar suas tripulações. Atualmente, sabemos que a lenda desse monstro foi baseada em encontros com lulas-gigantes. Esse animal pertence ao gênero Architeuthis e foi alvo de muitos estudos científicos. Apesar de seu enorme tamanho (pode chegar a 18m), a lula-gigante é incrivelmente elusiva e muito de sua biologia permanece desconhecida. Assim, envolto em mistério, Architeuthis é quase um ser mitológico, ocupando um lugar tanto na ciência como no mito: a última das lendas a persistir nos dias de hoje.
... Our results are in accordance with observations of giant squid beaks. Roeleveld (2000) examined beaks of Architeuthis species from North Atlantic, South Africa and New Zealand and found no consistent morphological evidence to indicate more than one species of Architeuthis in those areas, results corroborated in more recent times by molecular data (Winkelmann et al. 2013). Parallel examination of Todarodes sagittatus and T. angolensis beaks by the same author resulted in a clear separation of the two species and between both species and Architeuthis (Roeleveld 2000). ...
... Roeleveld (2000) examined beaks of Architeuthis species from North Atlantic, South Africa and New Zealand and found no consistent morphological evidence to indicate more than one species of Architeuthis in those areas, results corroborated in more recent times by molecular data (Winkelmann et al. 2013). Parallel examination of Todarodes sagittatus and T. angolensis beaks by the same author resulted in a clear separation of the two species and between both species and Architeuthis (Roeleveld 2000). These results support the importance of beaks as a tool for identifying cephalopod species. ...
Article
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The genus Octopoteuthis includes squids inhabiting meso- and bathypelagic waters worldwide. Of the seven presently named species distributed in the world’s oceans, only Octopoteuthis sicula has been reported for certain in the Mediterranean Sea to date. However, mixed and confusing descriptions of the systematic characters useful for identifying the species occur in the literature. Similarly, molecular analysis results available for the genus are contradictory and inconsistent. The research herein was undertaken firstly to clarify the systematic status of the genus in the Mediterranean Sea and confirm the presence of a single species, namely O. sicula. Additional goals were the assessment of the validity of systematic characters to identify the species and the analysis of beak morphology to provide useful tools in prey–predator relationship studies. Octopoteuthis specimens from various areas of the Mediterranean Sea and the Atlantic and Pacific oceans were compared, and the analysis of traditional morphological characters was combined with molecular genetics and the study of beaks. Molecular genetics and beak morphology results support the existence of a single species in the Mediterranean Sea. Additional evidence would suggest that this species is also distributed in the north-eastern Atlantic. The morphological characters reported in the literature to identify O. sicula did not identify Mediterranean specimens, with the exception of the two tail photophores. All information collected supports the need for a reconsideration of morphological characters used to identify Octopoteuthis species.
... Thus, the aim of these analyses was to explore body length of Architeuthis using a variety of different data, as well as updating previous analyses (Roeleveld, 2000) of the relationships between ML and beak size with the aim of determining the maximum size of squid taken from a sperm whale and plausible estimates of standard and TLs from the largest ML known. ...
... Model selection was as above. Unlike Roeleveld (2000), I regressed ML on beak size rather than the other way around. 3 SL was regressed against ML (with additional variables of sex and mode of discovery albeit without the three-way interaction because of a paucity of combinations). ...
Article
Giant squid are among the largest invertebrates known, but a consensus on their maximum size is lacking. Statistical investigation of various measures of body length and beak size in Architeuthis suggests that squid of at least 2.69 m (99.9% prediction interval: 1.60–3.83 m) mantle length (ML) may be handled by large bull sperm whales but perhaps not females. Given the relationship of squid ML to standard (from tip of mantle to end of arms) and total (from tip of mantle to end of tentacles) length, the observed spread of individual lengths, along with a longest reliably measured ML of 2.79 m, purported squid of 10 m standard length and even 20 m total length are eminently plausible.
... ln M=-1.773+4.57ln LRL (n=11 for ML; n=9 for M) (Clarke 1986) For relationships between ML and LRL, ML=10 (logML=(LRL+19.3)/11.2) (n=43) might be better (Roeleveld 2000) with ML= mantle length (in mm), M= mass (in g) and LRL= lower rostral length (in mm). ...
Book
Full-text available
The research in Southern Ocean cephalopods is always an ongoing work. There were three main reasons to publish an updated book on beaks from Southern Ocean cephalopods: Firstly, our motivation is that the guide is used in the future without providing confusion on species taxonomy, Secondly, various mistakes on the original printed version of this book were identified and needed correction; and finally, there were considerable changes in the taxonomy of various species recently updated (see Cherel 2020). Therefore, this new guide revisits the names of many beaks of cephalopods from the Southern Ocean (see Table 3), whose backbone of the structure of the book is untouched. We encourage colleagues to keep inform us on their research in this field, on new allometric equations for specific species and any further that can contribute to a later version of this book in the future. José Xavier & Yves Cherel (March 2021)
... Lower rostral lengths (LRL) of squids and lower hood lengths of octopuses were measured with a vernier caliper, and the size of cephalopods was estimated from allometric equations between LRL and dorsal Values are means7SD with ranges in parentheses. mantle length (ML) and wet mass (M) (Clarke, 1962(Clarke, , 1980(Clarke, , 1986aAdams and Klages, 1987;Rodhouse and Yeatman, 1990;Lu and Williams, 1994;Jackson, 1995;Roeleveld, 2000;Piatkowski et al., 2001;authors' unpublished data). For the few species where no relationships were available, ML and M were estimated from equations for closely related species or for species with a similar morphology. ...
Article
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Only five species of sharks have been recorded in the Southern Ocean, where their biology is essentially unknown. We investigated the feeding habits of the three commonest species from stomach content analysis of specimens taken as bycatches of the fishery targeting the Patagonian toothfish (Dissostichus eleginoides) in upper slope waters of the Kerguelen Archipelago. The three species prey upon a diversity of fishes and cephalopods. They segregate by feeding on different species of squids of different sizes. The small lanternsharks (Etmopterus cf. granulosus; 0.3 m on average) feed on small-sized Mastigoteuthis psychrophila, while the large porbeagles (Lamna nasus; 1.9 m) feed on small-sized histioteuthids (Histioteuthis atlantica and H. eltaninae) and on medium-sized juvenile ommastrephids of the genus Todarodes. Finally, the huge sleeper sharks (Somniosus cf. microcephalus; 3.9 m) prey upon large-sized cephalopods (Kondakovia longimana and Taningia danae) and giant squids (Mesonychoteuthis hamiltoni and Architeuthis dux). Thus sleeper shark is a fish with sperm whale-like feeding habits and, hence, the second top predator known to science to rely significantly on giant squids. Prey species and biology indicate that porbeagles are pelagic predators in the entire water column, while sleeper sharks are mainly benthic top predators and scavengers. The present study also underlines the diversity and biomass of the poorly known cephalopod fauna, including giant squids, occurring in outer shelf and upper slope waters surrounding subantarctic islands.
... The monogeneric family Architeuthidae has a worldwide distribution (Nesis, Amelekhina et al., 1985). Although as many as 20 nominal species have been described, consensus amongst modern teuthologists exists that most of the proposed names are synonymous and recent studies on beak morphometrics do not reveal taxonomic differences between specimens from the Atlantic Ocean and New Zealand (Roeleveld, 2000). ...
Article
The reproductive system is described from 15 giant squid Architeuthis sp., collected between 1972 and 2002 in South African waters. Distinctive features of the male reproductive system are the long muscular terminal organ, with elaboration of the anterior end, and modification of the tips of the ventral arms, probably hectocotilization. The spermatophoric organ has a long finishing gland that extends from the base of the gill. The terminal organ is differentiated internally into three distinct parts, involved in the guidance, storage, protection, expulsion and possibly the coating of spermatophores. Length of spermatophores in the terminal organ varied considerably. Several stages of spermatophores were found, from tentative to false to fully formed spermatophores, within a single animal. Distinctive features of the female reproductive system are a mesentery surrounding the main blood vessels of the ovary and attaching the ovary to the dorsal gladius chamber, multiple branching (at least three times) of the genital aorta that supplies the developing oocytes, high potential fecundity (3.5–6.2 × 10 6 oocytes), small eggs and short oviducts that suggest intermittent (extended) spawning. Large concentrations and single spermatangia were found in various places in females, indicating non-specific deposition. The transfer of spermatophores is probably rapid, perhaps because of considerable sexual size dimorphism (at maturity, males are much smaller than females). Implants in males are probably self-induced since the majority were found within reach of the terminal organ opening (primarily on the ventral arms in males).
... If the low mitochondrial diversity is indicative of variation at the nuclear genome level in Architeuthis, then the data strongly suggest that globally only a single species of Architeuthis exists, namely Architeuthis dux (Steenstrup, 1857) consistent with the suggestion of a previous study on Architeuthis beak morphometrics [17]. The genetic data also demonstrate Architeuthis lack phylogeographic structure. ...
Article
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Despite its charismatic appeal to both scientists and the general public, remarkably little is known about the giant squid Architeuthis, one of the largest of the invertebrates. Although specimens of Architeuthis are becoming more readily available owing to the advancement of deep-sea fishing techniques, considerable controversy exists with regard to topics as varied as their taxonomy, biology and even behaviour. In this study, we have characterized the mitochondrial genome (mitogenome) diversity of 43 Architeuthis samples collected from across the range of the species, in order to use genetic information to provide new and otherwise difficult to obtain insights into the life of this animal. The results show no detectable phylogenetic structure at the mitochondrial level and, furthermore, that the level of nucleotide diversity is exceptionally low. These observations are consistent with the hypotheses that there is only one global species of giant squid, Architeuthis dux (Steenstrup, 1857), and that it is highly vagile, possibly dispersing through both a drifting paralarval stage and migration of larger individuals. Demographic history analyses of the genetic data suggest that there has been a recent population expansion or selective sweep, which may explain the low level of genetic diversity.
... If the low mitochondrial diversity is indicative of variation at the nuclear genome level in Architeuthis, then the data strongly suggest that globally only a single species of Architeuthis exists, namely Architeuthis dux (Steenstrup, 1857), consistent with the suggestion of a previous study on Architeuthis beak morphometrics [17]. The genetic data also demonstrate that Architeuthis lack phylogeographic structure. ...
Article
Despite its charismatic appeal to both scientists and the general public, remarkably little is known about the giant squid Architeuthis, one of the largest of the invertebrates. Although specimens of Architeuthis are becoming more readily available owing to the advancement of deep-sea fishing techniques, considerable controversy exists with regard to topics as varied as their taxonomy, biology and even behaviour. In this study, we have characterized the mitochondrial genome (mitogenome) diversity of 43 Architeuthis samples collected from across the range of the species, in order to use genetic information to provide new and otherwise difficult to obtain insights into the life of this animal. The results show no detectable phylogenetic structure at the mitochondrial level and, furthermore, that the level of nucleotide diversity is exceptionally low. These observations are consistent with the hypotheses that there is only one global species of giant squid, Architeuthis dux (Steenstrup, 1857), and that it is highly vagile, possibly dispersing through both a drifting paralarval stage and migration of larger individuals. Demographic history analyses of the genetic data suggest that there has been a recent population expansion or selective sweep, which may explain the low level of genetic diversity.
... LRL (n=11 for ML; n=9 for M) For relationships between ML and LRL, ML=10 ((LRL/11.2)+1.723214286) (n=43) might be better (Roeleveld 2000) with ML= mantle length (in mm), M= mass (in g) and LRL= lower rostral length (in mm). ...
Book
Full-text available
Please see the LATEST UPDATE OF THE BOOK AT: http://nora.nerc.ac.uk/id/eprint/13035/ Any queries, contact Prof. José Xavier at jccx@cantab.net
... In the past it has been suggested that there have been up to 21 species of giant squid (Clarke 1966), however many descriptions were based on poorly preserved specimens and collection locality data (Roper, 1998;Ellis, 1998). More recent works have suggested that there are either three (Nesis, 1982) or one (Roeleveld, 2000) globally distributed species. Using a single marker from mitochondrial-DNA, Winkelmann's study strongly suggests that the family Architeuthidae consists of one pan-global species of giant squid, Architeuthis dux. ...
Article
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In 2004 the Natural History Museum, London (NHM) acquired an 8.62m long specimen of the giant squid Architeuthis dux Steenstrup, 1857. Complete giant squid are rare in museum collections and the chance to obtain a live-caught specimen with the potential for molecular analysis was an amazing opportunity. Also it was, and still is, the largest fluid preserved specimen at the NHM and although the preservation and storage presented numerous challenges, the squid’s public appeal as well as its scientific value has exceeded all expectations. I aim to show here the importance of such a specimen for the Museum collection, the difficulties met and overcome in all stages of its curation, as well as the numerous ways in which the squid has been used. These include such areas as education, the arts, exhibition, fund raising and public outreach, and its importance for the cephalopod research community.
... -Dorsal mantle length up to 2.5 m, only the female, whole animal with the tentacles is thought to measure up to 13 m in total. Larger sizes have been estimated (Roeleveld, 2000). The arms have two rows of suckers. ...
... -Dorsal mantle length up to 2.5 m, only the female, whole animal with the tentacles is thought to measure up to 13 m in total. Larger sizes have been estimated (Roeleveld, 2000). The arms have two rows of suckers. ...
Article
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We review the cephalopods currently living in the North Sea. Earlier studies have been used and additional data from both literature and internet-based data banks have been taken into account. Species previously recorded as living or at least occurring in the North Sea that we could not find or get confirmed by convincing reports are not listed here. The occurrence of Sepiola rondeletii Leach could not be verified; all earlier records are probably erroneous or misidentified. On the other hand the well identifiable Octopus vulgaris Cuvier is included in the list, currently not verified but expected to return. The species from the deeper part of the northern North Sea are less well known. Common species from that area are listed here but we might have missed some of the more rarely reported taxa. In total 20 species of cephalopods are living and reproducing in the North Sea. Sepiola ligulata Naef formerly restricted to the Mediterranean is listed here for the first time in the North Sea. Sepia elegans de Blainville and S. orbignyana Férussac are often reported from floating shells and from beaks found in the stomach contents of cod species. Reports of live animals of these two species living in the North Sea have not been confirmed. Rare reports of floating shells are listed at the end of this paper as non-indigenous species. Over the past few decades divers have made a considerable contribution to the observations of coastal species and their behaviour.
Article
Three individuals of small, young giant squid Architeuthis dux were caught in or near Japanese coastal waters during April–June 2013. The first occurrence of a young individual of 140.8 mm dorsal mantle length with a total weight of 44.81 g was recorded on the coast off Uchinoura, Kagoshima, Kyushu Island, southern Japan. The remaining two young individuals, both measuring 332.0 mm in dorsal mantle length with total weights of 390.63 and 356.95 g respectively, were caught on the coast off Hamada, Shimane, south-western Sea of Japan. Most morphological traits of all the specimens were consistent with those of A. dux , which was supported by further genetic analysis. Here we present some morphological traits of young giant squids with morphometric data and photographs.
Article
Combining the use of predators as biological samplers together with measurements of the stable isotopic ratios (δ13CBulk and δ15NBulk) of their sclerotized beaks help investigate foraging ecology of poorly known oceanic cephalopods. However, high chitin content (an amino-sugar macromolecule) lowers beak δ15NBulk values, thus precluding direct isotopic comparison with other tissues and organisms. To overcome the chitin effect, compound-specific isotopic analysis of amino acids (CSIA-AA) was performed on squid beaks. The method was applied on beaks and muscle, and the resulting δ13CAA and δ15NAA values compared between tissues. The usefulness of CSIA was tested by defining the habitat and trophic position (TPCSIA) of squids using their δ13CAA and δ15NAA values. Beak δ13CAA values were reliably measured on 12 AA that included five essential and seven non-essential AA, and δ15NAA values were quantified on at least seven AA that included two source and four trophic AA. Importantly, δ13CAA and δ15NAA varied little between muscle and lower and upper beaks, and TPCSIA estimates were identical whatever the tissue considered. Tissue δ13CAA values of both essential and non-essential AA reflected the latitudinal baseline δ13C gradient that occurs in the Southern Indian Ocean, while beak δ15NAA from source and trophic AA allowed disentangling the baseline effect from the trophic effect and thus better calculations of squid TP estimates than from δ15NBulk values. Beak δ13CAA and δ15NAA defined isotopic niches of colossal and giant squids, the two largest living invertebrates. In subantarctic waters, they segregate by having species-specific foraging habitats (using δ13CGly or δ15NPhe) and TPCSIA (using δ15NGlx and δ15NPhe). TPCSIA is higher in colossal (4.7) than giant (4.3) squids, and both values compare well with those of myctophid-eaters, suggesting very large squids prey primarily upon small zooplanktivorous fishes. As expected, CSIA-AA overcomes the chitin effect on beaks and it is a powerful tool to investigate trophic interactions of cephalopods. The method has a great potential with arthropods, because chitin is a main component of their exoskeleton but the deleterious effect of chitin is overlooked in isotopic studies focusing on crustaceans and insects.
Article
The tentacles of Architeuthis are very variable in length, from 0.2 to eight times mantle length (ML), and they increase in length with growth in ML. The tentacular clubs also increase in length with growth but not as fast as the whole tentacle. The Architeuthis club is unique in having both a triangular carpus with irregularly arranged toothed suckers and a fixing apparatus consisting of a cluster of smooth-ringed suckers and knobs in approximately equal numbers. The smooth-ringed suckers and the knobs extend in pairs proximally along the tentacular stalk for some 12-70% of the tentacle length. The proximal 14-28% of the tentacular stalk is devoid of suckers and knobs. The total number of suckers on the Architeuthis tentacle is remarkably constant during growth for so large and variable an animal. The manus and dactylus suckers do not appear to increase in number with ML but the lengths of these two club regions do increase, indicating growth in sucker size. The toothed carpal suckers and the smooth-ringed suckers of the fixing apparatus increase in number with growth, while the number of smooth-ringed suckers on the tentacular stalk remains the same. The length of the sucker-bearing tentacular stalk increases markedly with total tentacle length and ML, indicating increasingly widely spaced pairs of suckers and knobs. The relatively constant number of tentacular club and stalk suckers suggests that these suckers are of more than usual importance for the squids throughout ontogeny, probably mainly in feeding. The extensive locking apparatus of the carpus, fixing apparatus and stalk suggests that the two tentacles are held together to catch targeted prey, as has been observed in other squids. Stomach contents recorded for Architeuthis thus far are both demersal and pelagic in origin and include fast-swimming fishes and squids. Preliminary comparison of tentacle data from North Atlantic and North and South Pacific specimens showed some differences in relative dimensions and number of suckers, though variation is wide in both oceans.
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The first occurrence of a giant squid Architeuthis sp. specimen in Portuguese waters is noted and another reference set of biological and biometrical data provided which may in future be used in conjunction with others to Further elucidate important aspects of the identity, biology and ecology of the species. The fact that the specimen is a male is relevant, since males have been much less frequent in the reports in the scientific literature than have females. Additionally, this is the most southerly report of a male known to have occurred in the Atlantic Ocean.
Article
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Only one specimen of Architeuthis dux was previously reported from the southern Indian Ocean. The present work adds ten new records of giant squid in the area. Two remains of fresh specimens have been collected from La Réunion Island (21°S) and Amsterdam Island (38°S) in tropical and subtropical waters, respectively. Eight other squid were identified from beaks found in stomach contents of sleeper sharks caught in Kerguelen waters (47 to 48°S) located in the southern Polar Frontal Zone. These new data together with published and unpublished information on the food of seabirds and marine mammals indicate that giant squid have a wide distribution throughout the southern Indian Ocean.
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Article
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A specimen of Architeuthis was caught on the Fladen Ground, c. 100 miles NE. of Aberdeen (Scotland) in 1982. The animal, a male with a mantle length of 900 mm and a minimum total mass of 18 kg, was probably mature. Some measurements are given and the occurrence of spermatangia (inverted spermatophores) implanted in the ventral arms of the animal is discussed.
Article
A detailed study of 16 Architeuthis specimens obtained from New Zealand over a period of 15 years has revealed very high inter-individual variability. Each previously used taxonomic character has been measured and compared with the historical literature. Characters commonly used in other families, as well as several new characters, have also been noted and measured. New information is presented on external morphology, internal organs, diet, and distribution. Skin colours and textures have been recorded, arms and suckers have been examined in detail, and several tentacle clubs were available for study. Some food remains were identified which suggest that Architeuthis feeds mainly on mid-size deepwater fishes and a variety of smaller squid. Some crustacean fragments were also present. Trawl-caught specimens showed a preference for depths between 300 and 600 m deep, corresponding to the edge of the continental slope around New Zealand. In the process of examining which of the four Architeuthis species previously described from New Zealand best fitted the present specimens, it became necessary to examine the rationale for the erection of Architeuthis species throughout the world. Progressive scrutiny of each taxonomic character used by previous authors, in the light of variation exhibited by the present set of specimens, has resulted in the proposal that the family Architeuthidae should reduce to a single genus and species. The only defensible species is that of the earliest adequate description, Architeuthis dux Steenstrup. A revised summary description is presented, diagnosing the characters of the family and genus.
Article
Beak shapes in nine species of Southern Ocean octopodids were measured using seven size-standardized ratios. The results were analysed using principal component analysis and discriminant function analysis and show that beak shape may be used as a taxonomic character to distinguish between genera, but not between species. Stepwise discriminant function analysis indicated that all seven ratios were required to maximize discrimination between beaks. A phenogram constructed from a matrix of Mahalanobis distances differed from a dendrogram produced from genetic data. This suggests that, although useful for discrimination, beak morphology is probably not suitable for constructing phylogenies.