Central Annals of Marine Biology and Research Bringing Excellence in Open Access
Research Article *Corresponding author Tsunemi Kubodera, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba-shi, Ibaraki 305-005, How the Giant Squid, Japan; Tel: 81-29-853-8344 Fax: 81-29-853-8998; Email: [email protected] Architeuthis Dux, Maneuver Submitted: 07 January 2021 Accepted: 09 March 2021 Published: 31 March 2021 Long Tentacles for Hunting Copyright © 2021 Kubodera T, et al. Tsunemi Kubodera1*, Yasuhiro Koyama2 and Wen-Sung Chung3 1Curator Emeritus, National Museum of Nature and Science, Japan ISSN: 2573-105X 2Executive Producer, NHK ENTERPRISES (NEP), Department of Nature & Science OPEN ACCESS Program, Japan 3Queensland Brain Institute, The University of Queensland, Australia Keywords • Mesopelagic habitat Abstract • Twilight zone • Giant squid Having a large body, long tentacles, sharp beak and sucker ring teeth to battle against • Hunting behaviour a sperm whale in deep water makes the giant squid, Architeuthis dux, capture imaginations • Tentacles and constantly fire debate and interest. The hunting strategy of the giant squid in the twilight realm, particularly how to manipulate the soft and long tentacles (e.g.>5m length of a sub- adult), to catch prey, remains largely unknown. Here we present the first in situ behavioural observation of the tentacular strike of the giant squid which attempted to capture the artificial bioluminescent lure in its natural habitat (800 m depth), off Australian waters. Firstly, this footage confirmed that two long tentacles can be firmly held together by extensive paired locking apparatus (smooth-ringed suckers and knobs), along the tentacular stalks. The elastic locked tentacles bearing nimble tentacular clubs allow a ballistic strike onto a small light lure in distance. Also, the remarkably rapid changes of arrangement of tentacular clubs from the noose shape to the claw-like structure to grasp objects indicate that the giant squid likely relies on good vision (enormous eyes), chemotactile (suckers), or both for prey hunting.
INTRODUCTION
The tremendous size of the giant squid, Architeuthis dux, with capturestill camera initial with attack the bystrobe-light tentacles butsystem showed developed a large byball Professor of rolled its football-sized eyeballs and the imprints of suckers on the skin Naito, Japan Polar Research Institute. The first still image did not of sperm whales makes it capture the imaginations, resulting the retraction of these tentacles once a prey has been captured up long tentacles at the base of spread arms. It appeared that A. duxdebate is a and single interest species in public and widely and scientific distributes sectors in temperate [1-6]. To date, and (Supplemental Figure 1). scientific records of the giant squid, dead or alive, show that Furthermore, using a combination of approaches which insubarctic the mesopelagic regions of twilight all oceans zone [3,6-18]. (200 - 900 Fishery m depth) survey where and seaincluded camera two system, manned a follow-up submersibles project with successfully the ultra-sensitive captured theHD thefilming downwelling activities daylight revealed is that continuously the giant diminished squids often and dwell the cameras, a whale-borne camera and the unmanned Medusa deep-
attemptsfirst footage are of deployment the live giant in squid the right in its areas natural of habitat the ocean around and spectral range is tuned to constant blue spectra over increasing Ogasawara waters in 2012 [21,22]. Two keys to success in these depths [6,19-24]. With occasional encounters of the live giant squid during scientific or fishery activities [6,20-22], the hunting minimisation of disturbance during observation. In particular, behaviour of the giant squid remains largely unknown due to the unmanned and silent camera system, Medusa, equipped difficulties to observe this mysterious creature in the depths. with the animal invisible far-red illumination (8 dives down to 770m depth and 1 dive to 1100m, total 246 hours of observation) Rapid development of advanced underwater and camera provided the firsthand evidence that the giant squid still relied on technology (e.g., baited camera systems, manned submersible) visual contact for searching potential food in distance where the have led the recent success in filming the living giant squid and bait contained only artificial blue bioluminescence in the twilight revealing fundamental insights of the life of this mysterious realmThese [21-23,25]. images showed that these giant squids approached Ogasawaradeep-sea creature water where [6,20-22]. hundreds In 2005,of time-lapse Kubodera images and of Morithis [20], reported that the first live giant squid at 900 m depth in toward the baited-camera (ca. 600-750 m depth) using arms to individual (1 frame per 30 second), were recorded by a digital touch the food-bait or the light lure (electronic jellyfish equipped Cite this article: Kubodera T, Koyama Y, Chung WS (2021) How the Giant Squid, Architeuthis Dux, Maneuver Long Tentacles for Hunting. Ann Mar Biol Res 7(1): 1031. Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access inferences of the mysterious life of the giant squid, rendering two
renowned documentaries in 2013 [21,22]. Given occasional encounters of the living giant squid bait capture behaviours, knowledge of its hunting strategies (e.g., arm versus tentacular attacks, vision versus other senses in foraging) remains largely unknown [5,20]. A long-standing question of the ofgiant a sub-adult) squid hunting for a rapidis how and to useaccurate its extra-long strike is atentacles particularly to catch bio- prey. Casting the extraordinary long tentacles (e.g., over 5 m long
mechanic challenge, even just keeping both in a straight trajectory ringedtoward suckers one targeted and knobs) object. along Since with Roeleveld the tentacular [27] proposed stalks of that the giantthe extensive squid could locking hold apparatus tentacles (a together cluster of to the catch paired the targetedsmooth-
prey, no direct behavioural observation of the tentacular strike using the locked tentacles has been recorded before this study. During the latest NHK nature documentary project on extra- large marine animals off Bremer Bay, south-west Australia in howearly 2020, the giant an unexpected squid stretched large giant the squid locked was tentacular filmed at depth stalks of 800 m. Here we present the firsthand evidence to demonstrate
combined with the nimble activities of tentacular clubs to catch the light lure. This observation also showed how the giant squid coordinatedMATERIALS its tentacles AND METHODS and arms to handle objects.
The video filming operation for large deep-sea animals was conducted by NHK nature documentary TV program team led by Producer Y. Koyama, and Captain P. Cross and crew members of a whale watching vessel, Dhu Force (17.3m length). A unique predatory behaviour of the giant squid was recorded using a custom-made 4K Deepsea Camera thand LED illumination system from approximately 800m depth (34.46S, 119.35E) in the Bremer Bay,4K Deepsea south-western Camera Australia and onillumination 19 March 2020 system (Figure 1).
Vision of pelagic and deep-sea cephalopods tends to possess blue-shifted sensitivities toward the spectral peak (λmax) Figure 1 480nm (blue), thus these creatures are unlikely to detect dark- or infra-red illumination (>750nm) [25]. Using animal invisible Deployment location of the camera system. illumination therefore minimises behavioural disturbance during filming in their natural habitats, leading to a new custom- with a circular blue LED array (λmax 485nm), also known as made deep-sea camera platform which was developed by the e-jelly) [20-23,26]. Given the information of the living depth of the cooperation of NHK ENTERPRISE.INC (NEP), and Institute of giant squid (600 and 900 m) obtained from these two successful Industrial Science, the University of Tokyo, (weighed 10kg in projects [20-22], this guided the follow-up dives using the two air and operated at a maximum depth of 1500m). This camera manned submersibles, Triton (3 passengers) and Deep Rover (2 platform consisted of a camera blimp (a cylinder housing (15cm passengers), to explore within this narrow water column (600- diameter), equipped with the 4K SONY Action Cam, FDR-X3000, 800 m). Finally, the Triton equipped with an ultra-high sensitive frame rate: 30fps), mounted at the centre of the aluminium bar HD video camera (developed by NHK technical department, (1 m). Two light blimps (a cylinder housing (10cm diameter) Tokyo) managed to film extraordinary footage of the giant squid equipped with 5 infra-red LEDs), were mounted on both ends which it captured a large baited squid (1 m long) tethered on the of the bar to provide a broad coverage of illumination at the Triton at the depth of 630 m. The filming activities were lasted main camera scene (Figure 2). Apart from the main 4K camera, another compact 4K video camera (Gopro HERO6, frame rate: for over in situ 23 minutes to observe this individual in a close range (<5 m), until descending to the depth of 900 m. All these first 60fps) placed in the underwater housing with a build-in white ever video images (e.g. body form, skin colour, close-up of LED (Seatool product; 1000m depth pressure resistance) was large eyes and activities of arms) revolutionised some previous attached on polyethylene rope approximately 1m above the main Ann Mar Biol Res 7(1): 1031 (2021) 2/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access
Figure 2
Custom-made deep-sea camera system (a) Illustration of the Deepsea Camera system (b) The system during the deployment viewed by the upper surveillance camera. the locked-tentacular stalks which were tightly “held” together camera system to provide an overview of videographic scene. (Figure 3b-c). The first attempt to catch the e-jelly using the A newly developed electronic light lure, a flat e-jelly, was locked tentacles, the tentacular clubs rapidly formed into another noose was unsuccessful. Consecutively, while withdrawing the equipped with 2 circular arrays of blue LEDs (diameter of the LED ring: 10cm) to emit artificial bioluminescent illumination. The This is designed to imitate the bioluminescent alarm signal of the shape, the claw-like structure, where the proximal end of two lure displays in circularAtolla flashing waves running counterclockwise. Thisclubs “claw-like” (carpus and structure fixing apparatus) thus allowed remained the nimble attached tentacular with loose dactylus (the distal end of tentacular club) (Figures 3c-e). mesopelagic jellyfish [28]. A combination of attractant, e-jelly and food-bait (mackerel) was tethered on monofilament clubs to grab the e-jelly (Figures 3c-e). This sequence of the nylon rope 50cm away from the main camera. This 4K Deepsea tentacular bait catching behaviour was 3.6 seconds. Tentacular Camera system was tethered by a polyethylene rope (9mm clubs then rubbed the e-jelly using the dactylus for approximately diameter) on a large surface buoy and deployed down to 800m 10 seconds before it disappeared from the video scene. After six depth where the averaged seafloor depth was approximately seconds, several arm tips entered the camera scene and pulled 1100m. The camera system was then drifted by the current until down the attractants. Consecutively, the squid flared several long retrieval, resulting 5.66 hours footage (dive time from 10:30 to The main camera thus recorded the close-up images of arm arms to grab the e-jelly, the food-bait bag and the camera system. 17:00Footage local analysis time). movements, the arm protective membrane, arrangement of the arm suckers and the sucker ring (12 small blunt teeth counted All video images from both cameras were reviewed carefully fromEstimation a half sucker of the ring) body (Figures size 4a-e). by authors. The behavioural sequence of the bait catching was tentacularthen extracted club fromwas estimated the original by comparison footage and with then the examined known closely under the high-definition monitor. The size of the The body size of this individual was estimated using the published regression equation (mantle length (ML) versus sizeRESULTS of the e-jelly and the camera bar. tentacular club length (TCL) based on 7 individuals of the giant squid (ML: 1200-2200 mm, r = 0.942)) by Kubodera and Mori local time after the white light from the upper camera worn out [20] as follow: A large giant squid was filmed around 800 m depth at 14:13 Y = 2.393X - 107.956 (3h43m after camera deployment). Artificial bioluminescent where Y is the mantle length (mm); X is the tentacular club length flashes of the e-jelly triggered an initial interest of the giant squid (mm). to attack the light lure, rendering total 54.7 seconds footage obtained from both cameras (Figures 3, 4). The sequence of the thicknessGiven theof the known united size shaft of the of tentacles e-jelly (10 on cm the diameter), camera scene and bait-catching behaviour of this individual using tentacles and the length of the bar (1 m), of the camera system (Figure 2), the arms was recorded. Initially, two elongated tentacular clubs formed a finger-rhombus noose (Figure 3a, long edge: ca. 80cm, was close to the size of the e-jelly (Figure 3c). Furthermore, the short edge: ca. 30cm) came into the camera scene followed by tentacular club length (TCL), was estimated approximately 1.0 – Ann Mar Biol Res 7(1): 1031 (2021) 3/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access
Figure 3 long tentacular Time-synchronised stalks stretched image forward sequence and passed of the electricby the electric jelly capturing jelly, c: twistedbehaviour tentacular of the giant clubs squid when with withdrawing, long tentacles d: the from claw-like the main tentacular camera (left images) and the upper surveillance camera (right images). a: finger rhombus noose formed with right and left tentacular clubs, b: the locked structure, e: dactylus, distal end of tentacular clubs, rubbing electric jelly. Ann Mar Biol Res 7(1): 1031 (2021) 4/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access
Figure 4 the camera Time-synchronised system, c: a large image muscular sequence arm sucker of the adheredmain camera to the holding shield behaviourglass of the of housing the giant of squid the main with camera,long arms d: fromdetached the main the main camera camera (left images) and the upper surveillance camera (right images). a: several waiving arms to hold the main camera, b: the arm crown explored and retained system, e: releasing the electric jelly and the bait bag. Ann Mar Biol Res 7(1): 1031 (2021) 5/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access
Figure 5 Tentacles and locking apparatus of Architeuthis dux
(modified from Lu and Chung [18]) (photo courtesy of Kwen-Shen Lee). a: a pair of intact tentacles of a mature male giant squid (ML: 89cm; this specimen was kept in the National Museum of Natural Science, Taichung, Taiwan). The elongated tentacular club divides into distinct dactylus, manus and carpal. b: a close-up of a cluster of paired locking apparatus at the carpal region. c: a close-up of the well-matched locking apparatus along the tentacular stalks. Circles indicate the smooth-ringed suckers; dash circles show the knobs. Scale bar: 5cm.
1.2 m (Figure 3a-b), suggesting that the ML of this giant squid is in dim mesopelagic areas is difficult, thus visually-guided prey between 2.3 and 2.8 m. The estimate of the body size of this large capture or predator avoidance behaviours of the giant squid is individual could be one of the exceptionally large giant squid often speculated based on morphology and optic modelling [4]. hithertoDISCUSSION scientifically reported. For instance, with football-sized eyeballs which boost photon bothcatch, bioluminescent the corresponding light sensitive source and eyesight the silhouette of the giant of prey squid or predatoris proposed against to expand downwelling the visual sunlight range extensively and bioluminescence in detecting the Belowknowledge 500m gap depthof functional in the biology ocean, of deep-sea high pressure, cephalopods cold temperature and sparse food reduce the density of life. Filling up the giant squid stomach content showed that a large proportion (e.g. detection of a sperm whale ca.100m away). Examinations of about functional biology and sensory ecology of deep-sea of food content consists of bioluminescent creatures such as onychoteuthid and histioteuthid squid, suggesting food cephalopodalso remains challenging are mostly for based all these on reasons. anatomical To date, structure inferences and in situ
preference to bioluminescent items [27]. Also, recent comparisons with those well studied coastal species [4,27,29-31]. observations confirmed that the artificial bioluminescent flashes Along with rapid development of underwater filming technology, (e-jelly), can attract the giant squid [21,22,24], suggesting that a growing number of direct observations on giant squid from dynamic bioluminescent flashes, biological and artificial ones, are previous and current studies has revealed fundamental insights able to trigger visually-guided foraging behaviours of the giant of the visually-guided hunting behaviours (arm crown and squid. tentacular attacks) of this huge squid [6,20-22]. These rapid food paired smooth-ringed suckers and knobs) along the giant squid capture behaviours of the giant squid further confirmed that they tentacularPossessing stalk consistent in different well-matched life stages was locking proposed apparatus as a critical(ca. 26 are fast visual predators rather than the presumed gelatinous sluggish midwater drifters. adaptation in order to hold two extra-long tentacles together for Determining the factors critical in predatory competitions Ann Mar Biol Res 7(1): 1031 (2021) 6/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access danae a straight trajectory toward one targeted object (See Figure 5 ), was reported amongst several deep-sea camera platforms in this study and the Figure 11 and Table 3 in Roeleveld [27]). over the past decade [21-24]. Further observations using animal Here the footage provided the first direct evidence to confirm invisible illumination would be an efficient and friendly way to this proposed function and uncovered some unexpected nimble explore the vast deep ocean and could significantly improve our tentacular club clubs activities where the (Figure attached 3). Firstly, carpals the were current held footage by the understandingACKNOWLEDGEMENTS of visual ecology in the twilight realm. lockingrevealed apparatus a unique (smooth-ringed finger-rhombus suckers noose and formed knobs) by combined a pair of an open space at the manus region where numerous large suckers We thank Capitan Paul Cross and crew members Mathew with the touching dactylus (Figure 3a). This noose then formed Tidey and Jamie Anderson of the whale watching vessel, Dhu Force, for their support during the NHK nature documentary with sharp sucker ring teeth (diameter: 3-5cm) could effectively filming operation. Our thanks also go to cameraman Arata grasp an object prior to handling it with the extended arm crown. Gonatus onyx, Kashiwagi, and engineers Genki Okamura and Yuhei Sato for A similar tentacular noose structure has been briefly descripted promoting the present project by their professional abilities. in another active and muscular deep-sea squid, rhombus noose combined with the elastic locked tentacular We deeply appreciate Dave Riggs, local marine scientist and during ROV observation [32]. Thus, function of the finger- cameraman who gave us invaluable comments and suggestions. Special thanks go to Yoichi Minowa, coordinator and interpreter, ofstalks catching might the be light used lure like witha lasso the to tentacular capture a noose,small and the less-activetentacular forCONFLICT his great contribution OF INTEREST to promoting the project. clubsobject in rapidly distance changed with visual into guidance. the claw-shaped In addition, structure after failure and allowed to grab the attractants with the manus and the dactylus REFERENCESNone. All copy right of Figures 3, 4 belongs to NHK. bearingwhile retracting a pair of thetentacular locked clubstentacles forms (Figures a claw-like 3c-d). arrangement This image sequence further confirmed the feature that the locked tentacles 1. Roper CFE, Boss KJ. The giant squid. Scientific American. 1982; 246: 96-105. for prey capture originally suggested by Kubodera and Mori [20]. 2. Ellis R. The search for the giant squid: the biology and mythology of The final phase of the object captures of the giant squid in the world’s most elusive sea creature. New York, Penguin Group Inc. this sequence involved the extended arm crown to grasp and 1998. Architeuthis retain an entire camera system. Arms took 8.7 seconds to explore 3. Guerra A, Gonzalez AF, Pascual S, Dawe EG. The giant squid the camera system prior to pushing it away. In contrast, our : An emblematic invertebrate that can represent concern previous observation showed that the giant squid grasped a for the conservation of marine biodiversity. Biol Conserv. 2011; 144: natural baited squid for dozens of minutes in [21,22], situ indicating 1989-1997. that the giant squid can recognise the holding item (food versus support the hypothesis that the multiple function of the squid 4. Nilsson DE, Warrant EJ, Johnsen S, Hanlon R, Shashar N. A unique non-food) using arms and suckers. These observations advantage for giant eyes in giant squid. Current biology. 2012; 22: 683-688. arm suckers could involve in handling prey and mediating Architeuthis ( 5. coleoidRoper CFE,cephalopods Shea EK. Unanswered questions about the giant squid chemotactile recognition suggested by Hanlon and Messenger Architeuthidae) illustrate our incomplete knowledge of [31]. Furthermore, existence of well-developed optic lobes and . Am Malacol Bull. 2013; 31: 109-122. frontal lobe complex (inferior frontal and superior frontal lobes) giant squid, Architeuthis dux, encountered in Japanese coastal waters 6. Kubodera T, Wada T, Higuchi M, Yatabe A. Extraordinary numbers of were reported in the central nervous system (CNS), of the giant squid by Nixon and Young [29], suggesting that organisation of the Sea of Japan from January 2014 to March 2015. Mar Biodiv. lobes))of brain could lobes share and a the high known degree underlying of similarity function across (e.g.cephalopod vision- 2018; 48: 1391-1400. , related activities (optic lobes) and chemotactile sense (frontal 7. Aldrich FA. The distribution of giant squids (Cephalopoda Architeuthidae) in the North Atlantic and particularly about the groups, both large and small [29,33,34]. shores of Newfoundland. Sarsia. 1968; 34: 393-398. lightIn attenuationthe mesopelagic results environment in strong (200-1000m selection pressuresdepth), where for 8. Clarke MR. Cephalopoda in the diet of sperm whales of the southern food and mates are not abundant, decreasing visibility through hermisphere and their bearing on sperm whale biology. Discovery Reports. 1980; 37: 1-324. Architeuthis stranded near adaptations and potential signal summation mechanisms in remarkable visual adaption [4, 19,23,25,30,35,36]. These optical 9. Boyle PR. Report on a specimen of Aberdeen, Scotland. J Mollus Stud. 1986; 52: 81-82. cellular levels could significantly enhance the visual sensitivity of 10. Nesis KN. Cephalopods of the world: squids, cuttlefishes, octopuses deep-sea squids. Thus, it is critical to consider that the presence of and allies. Neptune City, New Jersey, Tropical Fish Hobbyist bright artificial illumination might temporarily blind squids and Publications, Inc. 1987. other vision-dependent creatures, and result in uncharacteristic Architeuthis based on a study of specimens from Newfoundland 11. Aldrich FA. Some aspects of the systematics and biology of squid of the behaviours [23,37-39]. In contrast, using the dark-red or growing number of in-situ Genus infra-red illumination which is invisibleA. dux , toDosidicus cephalopods gigas , [25],and T.a waters. B Mar Sci. 1991; 49: 457-481. Architeuthis in southern behavioural observations of the large 12. Roeleveld MAC, Lipinski MR. The giant squid and rarely-seen cephalopods (e.g. African waters. J Zool. 1991; 224: 431-477. Ann Mar Biol Res 7(1): 1031 (2021) 7/8 Kubodera T, et al. (2021)
Central Bringing Excellence in Open Access
: Oegopsida:
13. Förch EC. The marine fauna of New Zealand: Cephalopoda 31. Hanlon RT, Messenger JB. Cephalopod Behaviour. 2 ed. Cambridge, Architeuthidae (giant squid). NIWA Biodivers ArchiteuthisMem. 1998; 110: dux 1-113. in the Cambridge University Press. 2018. Gonatus onyx
14. Cherel Y. New records of the giant squid 32. Hunt JC, Seibel BA. Life history of (Cephalopoda : southern Indian Ocean. J Mar Biol Assoc Uk. 2003; 83: 1295-1296. Teuthoidea): ontogenetic changes in habitat, behavior and physiology. Mar Biol. 2000; 136: 543-552. 15. giantWinkelmann squid Architeuthis I, Campos PF,: genetics Strugnell sheds J, Cherel new lightY, Smith on one PJ, Kubodera of the most T, Sepia officinalis et al. Mitochondrial genome diversity and population structure of the 33. Boycott BB. The functional organization of the brain of the cuttlefish . Proceedings Biological sciences / The Royal Society. enigmatic marine species. Proceedings Biological sciences / The Royal 1961; 153: 503-534. Society. 2013; 280: 20130273. Architeuthis dux 34. Chung WS, Kurniawan ND, Marshall NJ. Toward an MRI-based 16. Roper CFE, Judkins H, Voss NA, Shea EK, Dawe EG, Ingrao D, et al. mesoscale connectome of the squid brain. iScience. 2020; 23: 100816. A compilation of recent records of the giant squid, 35. Robison BH. Deep pelagic biology. J Exp Mar Biol Ecol. 2004; 300: 253- (Steenstrup, 1857) (Cephalopoda) from the western north Atlantic 272. Ocean, Newfoundland to the Gulf of Mexico. Am Malacol Bull. 2015; 33: 78-88. 36. PartridgeRhynchohyalus JC, Douglas natalensis RH, Marshall NJ, Chung WS, Jordan TM, Wagner sized young giant squid Architeuthis dux HJ. Reflecting optics in the diverticular eye of a deep-sea barreleye 17. Wada T, Kubodera T, Yamada M, Terakado H. First records of small- fish ( ). Proceedings Biological sciences / The from the coasts of Kyushu Royal Society. 2014; 281: 20133223. Brachioteuthis beanie Island and the south-western Sea of Japan. Mar Biodivers Rec. 2015; 8: e153. 37. Roper CF, Vecchione M. In situ observations on (Verrill): paired behavior, probably mating (Cephalopoda, Oegopsida). 18. Lu CC, Chung WS. Guide of the Cephalopods of Taiwan. Taichung, Am Malacol Bull. 1996; 13: 55-60. National Museum of Natural Science. 2017 functional morphology in Mastigoteuthis 38. Roper CFE, Vecchione M. In situ observations test hypotheses of 19. Denton EJ. Light and vision at depths greater than 200 meters. In (Cephalopoda, Oegopsida). Light and life in the sea (eds. Herring P.J., Campbell A.K., Whitfield M., Vie Milieu. 1997; 47: 87-93. Maddock L.). Cambridge, Cambridge University Press. 1990; 127-148. Histioteuthis 39. Thomas KN, Robison BH, Johnsen S. Two eyes for two purposes: in situ 20. Kubodera T, Mori K. First-ever observations of a live giant squid in the heteropsis and Stigmatoteuthis evidence for asymmetric vision in the cockeyed squids wild. Proceedings Biological sciences / The Royal Society. 2005; 272: dofleini. Philos Trans R Soc Lond B Biol 2583-2586. Sci. 2017; 372: 20160069. 21. Koyama Y, Iwasaki H, Hamazaki T. Legends of the deep: the giant squid. (Japan Broadcasting Corporation (NHK), Japan. 2013. 22. Schwerin L. 2013 Monster squid: the giant is real. 2013. 23. Chung WS. Comparisons of visual capabilities in modern cephalopods from shallow water to deep sea. St Lucia, Australia, The University of Queensland. 2014. 24. Valentine K. NOAA-funded expedition captures rare footage of giant squid in the Gulf of Mexico. (NOAA reserach news). 2019.
25. Chung WS, Marshall NJ. Comparative visual ecology of cephalopods from different habitats. Proceedings Biological sciences / The Royal Society. 2016; 283: 20161346.
26. Raymond EH, Widder EA. Behavioral responses of two deep-sea fish species to red, far-red, and white light. Mar Ecol-Prog Ser. 2007; 350: 291-298. Architeuthis 27. Roeleveld MAC. Tentacle morphology of the giant squid from the North Atlantic and Pacific oceans. B Mar Sci. 2002; 71: 725- 737.
28. Widder EA, Robison BH, Reisenbichler KR, Haddock SHD. Using red light for in situ observations of deep-sea fishes. Deep-Sea Res Pt. 2005; 52: 2077-2085.
29. Nixon M, Young JZ. The brains and lives of cephalopods. Oxford, Supplemental figure 1 Oxford University Press. 2003. The first digital image of the live giant squid 30. Chung WS, Marshall NJ. Complex visual adaptations in squid for filmed by special deep-sea camera system off Ogasawara Islands in specific tasks in different environments. Front Physiol. 2017; 8:105. the western North Pacific in 2004 [20: Figure 3. (a)].
Cite this article Kubodera T, Koyama Y, Chung WS (2021) How the Giant Squid, Architeuthis Dux, Maneuver Long Tentacles for Hunting. Ann Mar Biol Res 7(1): 1031.
Ann Mar Biol Res 7(1): 1031 (2021) 8/8