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Print version ISSN 1984-4670
Zoologia (Curitiba, Impr.) vol.26 no.4 Curitiba Dec. 2009 Epub Dec 04, 2009
Rodrigo Silvestre MartinsI, 1; José Angel Alvarez PerezII
IZoology Department and Marine Research Institute, University of Cape Town. Private Bag X3, Rondebosch 7701, Cape Town, South Africa
IICentro de Ciências Tecnológicas da Terra e do Mar, Universidade do Vale do Itajaí. Caixa Postal 360, 88302-202 Itajaí Santa Catarina, Brasil
A carcass of a giant squid Architeuthis sp. was found afloat off Southern Brazil (28°05'S, 45°35'W) on 29 August 1999. The specimen was a mature female of 116 cm mantle length and had arms incomplete and tentacles missing. The specimen was morphologically similar to those previously described for the Southwest Atlantic, but a few peculiarities were found on the shape of the fins, head and the cross-section and length of ventral arms. Spermatophores were found embedded within the skin of the left ventral arm, at around 60 cm from the mouth, and could be traced to the core of the arm, radiating nearly four centimeters from the point of entry. This was the third record of Architeuthis in Brazilian waters and the eighth in Southwest Atlantic when the specimen was found.
Key words: Occurrence; morphology; reproduction; Southwest Atlantic.
Nearly 500 records of the giant squid Architeuthis Steenstrup, 1875 have been reported worldwide since 1547 (ELLIS 1998, SWEENEY 2001). Included in Architeuthidae Pfeffer, 1900, giant squid can reach up to 20 m and over 450 kg (NORMAN 2000). These are, along with the colossal squid, Mesonychoteuthis hamiltoni Robson, 1925, Cranchiidae, the largest known mollusks (ROPER et al. 1984, NESIS 1987). The species is thought to inhabit the oceanic environment, over continental slopes and seamounts, from surface waters up to 1,000 m or deeper (FÖRCH 1998, LORDAN et al. 1998, NORMAN 2000, HOVING et al. 2004). Most of the information available on the group historically derives from stranded specimens, dead or dying individuals found floating at sea surface and sperm whales (Physeter macrocephalus Linnaeus, 1758, Physeteridae) and sharks and oceanic predatory bony fish stomach contents (ROPER & YOUNG 1972, CLARKE 1980, 1996, ROPER & BOSS 1982, ALDRICH 1991, RÉ et al. 1998, SANTOS & HAIMOVICI 2002, CHEREL 2003, CHEREL & DUHAMEL 2004). However, individuals caught by fishing operations have been also reported (PÉREZ-GÁNDARAS & GUERRA 1978, 1989, ROELEVELD & LIPINSKI 1991, NORMAN & LU 1997, BRUNETTI et al. 1998, 2002, LORDAN et al. 1998, GUERRA et al. 2004, HOVING et al. 2004). Nonetheless, the first-ever observation of a live specimen in the natural environment was recently reported off Japan (KUBODERA & MORI 2005).
Most records of the genus come from the North Atlantic (LORDAN et al. 1998, GUERRA et al. 2004) where a single species, A. dux Steenstrup, 1857, is believed to occur (NESIS 1987, ALDRICH 1991, ROELEVELD & LIPINSKI 1991). In the Southwest Atlantic, Architeuthis was first recorded in 1989 off Southern Brazilian waters (27°24'S, 45°37'W) (ARFELLI et al. 1991). The specimen was a female found moribund floating over 3,400 m deep waters. Two other unreported specimens were found in Brazilian waters, the first one off Sergipe (Northeast), (A.S. Martins, Universidade Federal do Espírito Santo, pers. comm.) and the second one off Santa Catarina (Southern) (A.R.G. Tomás, Instituto de Pesca de São Paulo, pers. comm.), in 1997 and 2002, respectively. More recently, a fourth giant squid was reported off Rio de Janeiro in October 2007 (O ESTADO DE SÃO PAULO DIGITAL 2007), but unfortunately the fate of this specimen is currently unknown. South of Brazilian coast, another five specimens were reported along the coast of Argentina (BRUNETTI et al. 1998, 2002, RÉ et al. 1998).
On 29 August 1999, the crew of the Brazilian long-liner Macedo V spotted the body of a lifeless Architeuthis floating at the sea surface nearly 175 miles from Southern Brazilian coast. Carried aboard the vessel, the specimen was brought to the Itajaí harbor (Southern Brazil) constituting, at that occasion, the third record of the species in Brazilian waters and the eighth in the Southwest Atlantic. This paper describes the morphology of this specimen in comparison with the others recorded in South Atlantic and gives the first record of the Architeuthis skin sperm storage system in Southwest Atlantic.
MATERIAL AND METHODS
The examined specimen was found dead on 29 August 1999, by the crew of the Brazilian long-liner Macedo V floating over 2,400 m deep waters off the coast of Santa Catarina, Brazil (28°05'S, 45°35'W) (Fig. 1). Because of the heavy weight of the body, head and mantle were carried aboard separately, kept in crushed ice, and brought four days later to the Itajaí harbor, Santa Catarina, Southern Brazil.
Transported to the laboratory abroad, the specimen was identified as Architeuthis sp. on the basis of the straight simple mantle funnel-locking apparatus, absence of photophores, dorsal, dorsal, ventral and dorsal attachments of the buccal membrane to arms I, II, III and IV respectively (ROPER et al. 1984, NESIS et al. 1985) and its large size (Fig. 2). The external morphology was examined in detail. Head, arms and body were initially weighted and photographed. The dorsal mantle length (ML) was measured and further measurements and counts of several parts of the body were taken according to ROPER & VOSS (1983) (Tab. I). Morphological data were registered in a standardized form, as proposed by ROELEVELD & LIPINSKI (1991).
Body structure measurements, proportion and counts utilized for comparisons with available published data of other giant squid were (ROPER & VOSS 1983): (ALI IIV) arm length index IIV; (FLI) fin length index; (FWI)= fin width index; (FuLI) funnel length index; (FuWI) funnel width index; (GTF) number of gill filaments per outer demibranch; (HLI) head length index; (HWI) head width index; (LRL) lower beak rostral length; (ML) dorsal mantle length; (VMLI) ventral mantle length index; (MWI) mantle width index; (NGLI) nidamental gland index; (SDI IIV) sucker diameter index IIV; (TTLI) tentacle length index; (TCLI) tentacle club length index; (CL SDI) club sucker diameter index; (TL) total length; (TM) total mass (Tab. II). Except for GTF, ML, LRL, TL and TM, all the remaining indices were expressed as the proportion of the measured structure in relation to the ML.
Internal organs were described after the dissection of the mantle conducted by cutting along the midline of the ventral side. The body, the head and the internal organs were initially stored in formalin and then transferred to 70% ethanol.
Beaks and radula were extracted from the buccal mass and sucker rings were removed from sucker cups. All these structures were stored in a 3:1 solution of 70% ethanol and glycerol, in order to prevent dehydration of the material. Fragments of the gladius were dissected off the shell sac at the dorsal midline of the mantle and stored in formalin.
Beaks were measured using calipers to the nearest 0.1 mm, following CLARKE (1986) and WOLFF (1984). Beak measurements and proportions were RL(= a) = upper beak rostral length, LRL (= i) = lower beak rostral length, RC = rostral tip to inner posterior corner of lateral wall, lower beak, RW = rostral tip toinner margin of wing, either beak, WL (= b) = wing length, JW (= j) = jaw angle width, either beak, HdL (= g) = hood length in the midline, either beak, WCL = wing to crest length, upper beak, CL (= f) = crest length, either beak, WW = wing width, upper beak, c = rostral tip to baseline, lower beak, d = length of the baseline in profile, lower beak, e = distance the rostral tip lies behind the wing tip, lower beak, h = rostral base length, lower beak.
Statoliths were removed with forceps from the statocists by desiccating the nucal cartilage and measurements were taken under a binocular microscope at 20x magnifications. Because the left statolith was polished for age estimation (which unfortunately turned out to be unreadable), measurements were only taken on the anterior side of the right statolith, and the total length, lateral dome length and maximum lateral dome width were recorded according to LIPINSKI (1997).
Implanted spermatophores were found and the term "spermatangium" (NESIS et al. 1998) is used in the text as a synonym for the ejaculated spermatophore. The spermatangia were photographed, extracted and stored in 70% ethanol.
Funnel large and wide (FuLI and FuWI 38.8 and 32.7, respectively), muscular and well developed, with a broad, U-shaped, funnel valve. Funnel-locking apparatus of mantle simple, well developed, with a straight ridge on the mantle and a groove in the funnel. No funnel organ was found.
All arms but ventral ones (arm IV) were mutilated about the halfway, the latter reaching as much as 68.982.7% of ML (Tab. II). Ventral arms with a rectangular cross-section, more robust than dorsal ones. Dorsal arms triangular in cross-section. Swimming membranes observed only in the ventral arms. Arms suckers cup-shaped, pedunculate, with chitinous rings, ranging between 13 and 18 mm in diameter (SDI 1.11.6) (Tab. I).
Sucker rows biserial, running throughout the length of the oral surface of the arms. The tentacles were missing. Buccal membrane well developed, lacking suckers, attached dorsally to arms I and II and IV and ventrally to arm III (buccal formula: DDVD).
The inner wall of the mantle was covered with a dark reddish-brown skin (similar to Ommastrephes skin in color/texture) on its anterior edge, but it was missing from the middle-point length towards the posterior end of the mantle cavity. No visceral sac was found. The gladius was badly damaged and fragmented, and thus neither measurements nor further descriptions were attempted.
Gills well developed. Only the left demibranch was measured, and was 280 mm long, with 55 lamellae. The axes of both demibranchs were dark reddish-brown (like the skin of the inner wall of the mantle) and the lamellae creamy white. No distinct branchial hearts were found at the bases of the gills.
The reproductive system was disintegrated, remaining only few tiny (~ 2 mm in diameter), translucent yellowish, oval eggs scattered within the body cavity along with copious amounts of slime, which allowed the identification of the sex and also putatively regard the specimen as a mature, perhaps spent, female squid.
The digestive system was nearly intact. The stomach was sacular in shape, creamy white, reaching as much as the first 1/3 of the mantle cavity and, since it was lacerated laterally near its left terminal part, neither stomach contents nor the chitinous internal lining, the latter commonly cited by other authors, were found. The coiled caecum was rounded, pale pinkish, with distinctive septae visible through its walls, smaller than the stomach (± 1/3 of the stomach length) and was connected to the left anterior portion of the stomach. The systemic heart lied mid-ventrally, was roughly pear-shaped and grayish in color. Rectum long, tubular but flatted in shape, creamy white, ending in two well developed anal papillae. The renal appendages were brownish-gray in color, positioned just below the base of the gills, under the systemic heart, forming a flocculent mass, apparently not connected to any other particular structure. The oesophagus, intestine, digestive gland and ink sac were not distinguishable.
Beaks, statoliths and radula
The upper and lower beaks are depicted in figures 6-8. Beak measurements and indices are given in tables III and IV. Both beaks were dark pigmented having a whitish pigmentation along the borders of the wings and the posterior part (i.e. back to the hood) (Figs 6 and 7).The upper beak presented a sharp rostrum, curled downwards at tip, and broad (a/j = 1.54). Hood highly above the crest (f/g = 1.55). Crest slightly curved to straight. Wing base insertion just above the base. Lower beak short (c/d = 0.92), not squarish (d/f = 1.21) and obtrude (d/e = 1.91). Very short jaw edge in relation to wing length (b/i = 3.2), wide rostrum (i/j = 1.25) with no definite hook, no wing fold present, prominent shoulder tooth seen in profile, thickened crest with and large smooth lateral walls with an infold to the side of the crest.
Statoliths were elongated with long laterally bended rostrum, lateral dome with three distinctive lobes (Fig. 8). Only the right statolith was measured, and had 2.37 mm in total length, 1.71 mm lateral dome length and 1.05 mm maximum lateral dome width.
A frontal view of the radula is show in figures 9-10. Each row consists of seven teeth and two marginal plates, with a central tooth (rachidian) tricuspid, central cusp varying from equal to 1.5 times as long as outer cusp, bicuspid first lateral teeth with the tips pointing towards the rachidian tooth, second and third lateral teeth with large, triangular, single cusp, also with the tips pointing towards the rachidian tooth, and marginal plates reduced to a flattish plates. The sharpness of radular teeth tips varied according with the position of the row on the radula, being the central ones rounded and distal ones sharp (Figs 10 and 11).
Implanted spermatangia were found laterally in the left ventral arm. Three sperm cords were clearly noticed partially embedded in the skin (Fig. 12), protruding from a small hole at around 60 cm from the mouth. The spermatangia were creamy white. The dissection of this arm revealed that the spermatophores radiated nearly four centimeters from the point of entry, and presented different levels of intrusion (Figs 13 and 14). Interestingly, one spermatangium end was found near to the central nerve cord (Fig. 14).
The present record of Architeuthis constitutes, to date, the smallest female specimen of this squid species from the South Atlantic Ocean sector (Tab. II) and one of the smallest female recorded in the literature worldwide (see SWEENEY 2001 for a review). The fact that we putatively classified the female as a spent individual was based on the following factors: (1) the reproductive system was virtually missing, which may be due the degeneration of this structure after the spawn as in other oceanic squid species (NESIS 1995, NESIS et al. 1998), and (2) the size of the few eggs found approximated the dimensions of ripe Architeuthis eggs in mature giant squid (i.e., ~ 2.0 mm longest axis; BRUNETTI et al. 1998, ROELEVELD & LIPINSKI 1991, HOVING et al. 2004). However, this conclusion must be taken with reserves because, regardless of the stage of maturity, the reproductive system could simply decayed earlier than the rest of the internal organs and washed away during the post-mortem drifting of the animal.
The occurrence of giant squid in the reported geographical locations off Southern Brazil is not unexpected, since it roughly lies near the slope zone, where live adult giant squid have been often found (NORMAN & LU 1997, FÖRCH 1998, GONZÁLEZ et al. 2002, KUBODERA & MORI 2005). Additionally, such area is one of the canyons that characterize the continental margin morphology of Southern Brazil and is known as the "Canal de Itajaí" (CHAVES 1979). These geological features have been associated to deepwater fishing zones (PEREZ et al. 2002) and also to areas of frequent sighting records of sperm whales and other oceanic odontocetes (PINEDO et al. 2002), the actual and potential predators of Architeuthis (CLARKE 1980, 1996). The presence of Architeuthis prey and predators suggests that the local deep-water environment may perhaps sustain a resident population, or at least temporary concentrations, of giant squids, as in Northern Spanish waters (GONZÁLEZ et al. 2002). This is further supported by the geographically close previous occurrence of another Architeuthis specimen found afloat in the region (ARFELLI et al. 1991; see Fig. 1).
In general, the morphology of our specimen resembles the ones of giant squids found in South Atlantic and elsewhere. However, some differences were noteworthy and might not be overlooked. It seems that, from the present data and the results reported by RÉ et al. (1998) and BRUNETTI et al. (1998), the heads of southwest Atlantic giant squid are somewhat shorter and narrower than those reported for the North Atlantic (e.g., ALDRICH 1991, LORDAN et al. 1998). However, head indexes vary widely and are considered of little systematic value (ROELEVELD & LIPINSKI 1991). Additionally, the ventral head embellishment (fin-like structures) cited by RÉ et al. (1998) was not found in the present case.
Cross-section of giant squid arms can vary broadly depending on the point was it is taken (BRUNETTI et al. 1998). Nonetheless, it was observed that the cross-section of the arm IV was rectangular, more similar to the observations for North Atlantic and Southern African Architeuthis (ALDRICH 1991, ROELEVELD & LIPINSKI 1991) than to Argentinean records (BRUNETTI et al. 1998, RÉ et al. 1998). A further particularity was noticed in relation to the ventral arms. It is well established that Architeuthis squid has extremely long arms in relation with other squid species. However, in the present case, the length of arm IV reached only as much as 68.9 and 82.7% of ML (right and left respectively). In contrast, published data have often showed that the lengths of the arms, when intact, are longer or equal to the mantle length, i.e., ALI > ML (e.g., ROELEVELD & LIPINSKI 1991). On the other hand, the possibility that the tips of those arms were simply regenerated, given a mistakenly impression of a shorter arm length, could not be ruled out.
Regarding to the fin shape, the heart-shaped (cordiform) fin has been reported for some specimens from North Atlantic, Southern African coast, and off Argentina. This particular shape derives from free anterior lobes (ROELEVELD & LIPINSKI 1991, BRUNETTI et al. 1998, LORDAN et al. 1998, RÉ et al. 1998). However, this may be an artefact due to the decay of the material causing the fins to partially torn free from the mantle, and thus making any systematic value dubious.
The morphology of the beaks was quite similar to the others reported for Southwest Atlantic waters, although the pigmentation was not. The beaks of RÉ et al. (1998) specimen were somewhat darker when compared with ours. Additionally, the coma-like features cited by these authors were not found in our beaks. On the other hand, the coloration was fairly similar to ARFELLI et al. (1991) report, with conspicuously whitish borders, although these authors provided drawings, not actual pictures. This suggests that the animal was relatively young, as squid beaks color typically darkens as the animal grows mature (CLARKE 1986). Virtually all the lower beak ratios were quite similar to the ratios reported for the Bustamante Bay (Argentina) Architeuthis (RÉ et al. 1998) (Tab. IV) which were, in turn, quite similar to the ratios provided for two South African giant squids (RÉ et al. 1998).
Despite the differences in radular teeth sharpness at different places along the radula, which could be attributed to the natural worn and breakage of individual radular tooth along the rows, the general morphology was quite similar to the reported by RÉ et al. (1998) and ROELEVELD & LIPINSKI (1991), being typically architeuthid, with tricuspid rachidian, bicuspid first lateral, unicuspid second and third lateral teeth and marginal plate.
This is the first instance that implanted spermatangia in giant squid are recorded for the Southwest Atlantic, despite this phenomenon has been documented elsewhere: Northeast Atlantic: KJENNERUD (1958), Southwest Pacific: NORMAN & LU (1997), Southeast Atlantic: HOVING et al. (2004). Although implants have been found in several parts of Architeuthis external anatomy of both sexes (HOVING et al. 2004), spermatangia are often present embedded into the arms in female squid (NORMAN & LU 1997, HOVING et al. 2004).
It is unknown if (1) female giant squid lay the eggs embedded within gelatinous, neutrally-buoyant, egg balloons as in Ommastrephid and Thysanoteuthid squid (BOLETZKY 1998), (2) brood the egg masses within the arm crow as Gonatus onyx Young, 1972, Gonatidae (SEIBEL et al. 2000, 2005), or (3) cast the eggs individually as in some smaller oceanic squid families (e.g. Enoploteuthidae and Brachioteuthidae; YOUNG et al. 1985, NESIS 1995). However, the well-developed nidamental glands seem to suggest the first method (ROPER & BOSS 1982). Therefore, considering that such probable egg balloons would be expelled trough the funnel and manipulated with the arms as in other large oceanic squid families, the spermatangia in the present case were placed in a theoretically suitable place for egg fertilization (i.e., the inner side of the left ventral arm, relatively close to the opening of the funnel). However, how the female giant squid utilizes the skin-stored sperm is unknown (NORMAN & LU 1997, HOVING et al. 2004).
On the other hand, HOVING et al. (2004) suggested, based on a spermatangium found running from the surface of one of the arms into the central nerve cord (which we also observed in the present case, see figure 14), that the sperm cords would migrate inside the female's tissues (as in Galiteuthis glacialis (Chun, 1906), Cranchiidae; NESIS et al. 1998)), dissolving their way by a putative enzymatic mechanism. The skin sperm-storage system is also know to occur in a number of other smaller oceanic squid species, and is thought to be related with infrequent female-male mating encounters in such open waters (NESIS 1995).
The authors whish to thank the skipper and crew of the Brazilian long-liner Macedo V for providing us the specimen. We also extend our acknowledgments to H.J.T. Hoving (University of Groningen, The Netherlands) and three anonymous referees for the critical reading, suggestions and comments on the manuscript. M. Goodman (MCM) kindly improved the English of the early draft. J.A.T. Santos (UNIVALI) assisted during sampling activities, R. Sousa (UNIVALI) took some of the photos utilized in this report and R.C. Santos (UNIVALI) provided the geo-referenced map used in figure 1.
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Submitted: 01.XI.2008; Accepted: 22.XI.2009.