Overview

Brief Summary

Introduction

Taningia danae reaches a maximum of 170 cm ML (Nesis, 1981/87). In T. danae tentacles are reduced to minute appendages in young subadults and are absent in adults. The second arms carry large, lidded photophores at the arm tips.

Figure. Dorsolateral view of T. danae, 60 mm ML, Hawaiian waters. Photograph by R.Young.

Brief diagnosis:

An octopoteuthid ...

  • with large photophores at the tips of arms II; other arms without arm-tip photophores.
  • without "tail" photophores.

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Comprehensive Description

Predators

T. danae is a known, and probably important, component of the diet of the sperm whale (eg, (Clarke, 1967; Okutani & Satake, 1978). T. danae can be swallowed whole to at least 32 cm ML (T. K., personal observations) but larger ones, judging from the following account, must be torn up before swallowing.

Underwater observations and photographs of sperm whales feeding on squid are rare. According to a report written by the observers Wade and Robyn Hughes, Wayne and Pam Osborn, and Tania Windsor Blunden (personal communication): A young male sperm whale, about six to seven meters in length, surfaced off Faial in the Azores with a large squid in its jaws. Initially the whale "appeared to have ... taken [the squid] head on, with [the squid's] swimming fins hanging symmetrically down each side of the whale’s jaws." "After swimming on or near the surface for about ten minutes with the squid held in its jaws, the whale sank slowly on its side, and then on its back convulsively chewing and snatching at the squid’s carcass." In the picture below, on the right, fragments of the squid float near the whale indicating the "sloppy feeding" seen by the observers. They estimated the squid's width from fin tip to fin tip as 1.5 to 2 m; this width would approximate the squid's mantle length.


Figure. Sperm whale eating a squid, probably Taningia danae, photographed off the islalnd of Faial in the Azores. Left - Recently surfaced sperm whale and squid. Right - Later photograph in which the whale has a diffenent grasp of the squid and fragments of the squid are floating nearby. Photographs taken by Wade and Robyn Hughes while free diving (i.e., without scuba gear).

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Nomenclature

O. persica Naef, 1923 is a paralarva of Taningia (Young, 1972), presumably, T. danae.

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Characteristics

  1. Tentacles
    1. Tentacles reduced to minute appendages in young subadults; absent in later stages.

  2. Head
    1. Beaks: Descriptions can be found here: Lower beak; upper beak.

  3. Photophores
    1. Tips of Arms II modified into broad photophores with muscular lids.
    2. Figure. The large arm II photophore of T. danae. Left - Oral view of the brachial crown showing the large, dark photophores at the tips of arms II. Right - Two pictures showing aboral views of an arm tip photophore. The first shows the photophore lids closed. The second is a double photographic exposure that shows, with one exposure, the lids withdrawn (open) revealing the white surface of the photophore, and the lids closed with the other exposure. Photographs by R. Young and C. Roper.

    3. Pair of photophores present on viscera.

Comments

The visceral photophores are very hard to locate in preserved specimens.

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Distribution

semi-cosmopolitan
  • UNESCO-IOC Register of Marine Organisms
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Source: World Register of Marine Species

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Range Description

This species has a global distribution in tropical, subtropical and temperate waters, as well as the boreal waters of the North Atlantic (Vecchione et al. 2008).
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The type locality is off the Cape Verde Islands. The distribution includes the tropical and temperate regions of all oceans and boreal waters of the North Atlantic (Roper and Vecchione, 1993).

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Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
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mesopelagic
  • UNESCO-IOC Register of Marine Organisms
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Habitat and Ecology

Habitat and Ecology
Little is known about the biology and ecology of this very large mesopelagic species. However, limited catch data suggest this species may undergo a downward ontogenetic migration with planktonic paralarvae and small juveniles (~6-7 mm in mantle length) occurring in the upper 100 m in depth, larger juveniles (~15 mm in mantle length) to 300 m in depth, and subadults and adults are greater depths (Stephen and Jefferts 1992, Quetglas et al. 2006). Off Japan it has been photographed between 614 and 940 m in depth during the day, between 500 and 600 m at sunset, and between 240 and 650 m at night suggesting it may undergo diel vertical migration (Vecchione et al. 2008). This species may spawn on or near the bottom in deep-water (Roper et al. 1984, Santos et al. 2001), and unvalidated statolith growth increment analysis suggests this species may live for up to 3 years (Quetglas et al. 2006). Its diet includes crustaceans and finfish such as blue whiting, Micromesistius poutassou (Santos et al. 2001). It is preyed upon by sperm whales (Roper et al. 1984). This species has demonstrated bioluminescence on its ventral surface which may have a countershading function as well as temporary bright flashing illumination from the arms that may be used to distract potential predators or prey (Vecchione et al. 2008). It is characterised by the absence of tentacles in adults and a pair of large fins on its mantle which it uses to propell itself (Vecchione et al. 2008).

Systems
  • Marine
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Depth range based on 30 specimens in 1 taxon.
Water temperature and chemistry ranges based on 25 samples.

Environmental ranges
  Depth range (m): 55 - 2333.5
  Temperature range (°C): 1.913 - 21.554
  Nitrate (umol/L): 0.156 - 36.323
  Salinity (PPS): 34.430 - 36.605
  Oxygen (ml/l): 1.558 - 5.457
  Phosphate (umol/l): 0.030 - 2.466
  Silicate (umol/l): 0.798 - 109.387

Graphical representation

Depth range (m): 55 - 2333.5

Temperature range (°C): 1.913 - 21.554

Nitrate (umol/L): 0.156 - 36.323

Salinity (PPS): 34.430 - 36.605

Oxygen (ml/l): 1.558 - 5.457

Phosphate (umol/l): 0.030 - 2.466

Silicate (umol/l): 0.798 - 109.387
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Life History and Behavior

Behavior

Roper and Vecchione (1993) reported observations on bioluminescence in a 60 mm ML squid from Hawaiian waters. When disturbed, Taningia would attack and repeatedly flash the arm-tip photophores. The flash duration was generally only a fraction of a second; however on some occasions the arm tip glowed for periods of about 1-7 seconds. The aggressive flashing behavior is presumably used to startle predators via a mock attack. In addition, the visceral photophores were observed to glow for periods in excess of 15 min. and produced a general ventral glow. This latter behavior is suggestive of a counterillumination function (Roper and Vecchione, 1993). The photograph below left shows the squid on which these observations were made. The chromatophores are contracted on the midventral mantle skin which leaves a "window" for bioluminescent light from the viscera to emerge. The reflective photophores can be seen as a white streak. The photograph, below right, is from a different specimen that has the mantle cut open showing the visceral photophores.

Figure. Left - Ventral view of T. danae, 60 mm ML squid, Hawaiian waters. Photograph by R. Young and C. Roper. Right - Ventral view of visceral photophores of a young T. danae seen through a cut in the ventral mantle. Photograph by M. Vecchione.

T. danae has been observed with a baited underwater camera in its natural habitat off the Ogasawara Islands in the western North Pacific (Kubodera, et al., 2006). The squid was photographed at depth of 240-940 m overall and at 614 and 940m depth at 0800 -0900 hrs, at 900 m at 1600 hrs, mainly at 500-600 m around sunset (1700-1900 hrs) and at 240-650 m at night (2000-2300 hrs). The squid swam using the large fins. Large amplitude waves in the fins passing from head to tail propelled the squid forward and reverse waves propelled it backwards.


Figure. Series of video frames of T. danae as it approached the bait showing the movement of the large fins. © Tsunemi Kubodera

On several occasions a squid of over 1 m total length was seen to actively attack the bait, attaining swimming speeds of 2-2.5 m/sec during the approach.


Figure. Video frames of T. danae attacking the bait. Left - Approaching the bait with arms spread. Middle - Swimming around the bait and catching it with arms IV. Right - Grabbing the bait with all arms just before swimming off. © Tsunemi Kubodera

Insitu bioluminescence was also photographed by Kubodera, et al. (2006). The arm II photophores were seen to flash (< 2 seconds duration) as the squid attacked the bait with spread arms. The photophores were also seen to produce long-term glows (ca. 4-9 sec.) without attacking the bait, although swimming near the bait then extinguishing the light as the squid swam away. The function of the latter luminescence is uncertain. This behaviour was seen only when the two halogen lights adjacent to the camera were covered with red filters. Without the distracting large halogen lights visible, perhaps the squid interpreted the two dim lights hung above the bait as bioluminescence from another Taningia and its own glow was an attempt to communicate (e. g., "This is my prey") but without an appropriate response, the squid moved on (Kubodera, et al., 2006).


Figure. Video frame of T. danae producing a glow from its large arm II photophores (upper left arrow). The right bottom arrow points to the squid bait. The middle arrow points to two small lights attached near the bait which superficially appear similar in size and shape to the two squid photophores. The light and bait dangle on a line from a pole attached to the camera and large halogen lights that have been covered with a red filter during this sequence. © Tsunemi Kubodera

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Life Cycle

Life History

The paralarva is distinctive in having enlarged suckers on the thick tentacles and the tips of arms II swollen by the developing photophores.

Figure. Ventral view of the head of a paralarval T. danae, Hawaiian waters, mantle was missing. Drawing by R. Young.

Figure. Dorsal and oral views of a paralarva of T. danae, Gulf of Aden, 4.7 mm ML. Drawings from Chun, 1910. This is the paralarva that Naef (1923) named Octopodoteuthopsis persica.

The juvenile T. danae (photographs below) can be quite translucent although the armtip photophores are heavily pigmented. The eyes are large, and the central brain and optic lobes (yellow) occupy a posterior position in the head, leaving a long anterior esophagus passing to the buccal mass.

Figure. Ventral (left) and dorsal-oblique views of a juvenile T. danae, ca. 10-20 mm ML, Hawaiian waters. Photograph by R. Young.

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2014

Assessor/s
Barratt, I. & Allcock, L.

Reviewer/s
Young, R., Vecchione, M. & Böhm, M.

Contributor/s
Duncan, C.

Justification
Taningia danae is an oceanic species which has been assessed as Least Concern, as it has a wide geographic distribution, making it less susceptible to human impact. However, it is targeted by fisheries in some regions of its range, and further research is recommended in order to determine the precise distribution, population dynamics, life history and ecology, and how these threat processes affect this species.
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Population

Population
There is no population information available for this species.

Population Trend
Unknown
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Threats

Major Threats
This species is of some interest to fisheries (Roper et al. 2010), though the level of impact on the species is unknown. Other threats to this species are also unknown.
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Management

Conservation Actions

Conservation Actions
There are no species-specific conservation measures in place for this species. Further research is recommended in order to determine the precise distribution, population dynamics, life history and ecology, and potential threat processes affecting this species.
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Wikipedia

Taningia danae

Taningia danae, the Dana octopus squid, is a species of squid in the family Octopoteuthidae. It is one of the largest known squid species, reaching a mantle length of 1.7 m (5.6 ft)[1] and total length of 2.3 m (7.5 ft).[2] The largest known specimen, a mature female, weighed 161.4 kilograms (356 lb).[3][nb a]

Taningia danae is named after Danish fisheries biologist Åge Vedel Tåning (1890–1958), who often traveled on the research vessel Dana.

Hunting behaviour and bioluminescence[edit]

In 2005, a Japanese research team headed by Tsunemi Kubodera managed to film T. danae in its natural habitat for the first time. The video footage, shot in deep water off Chichi-jima in the northern Pacific Ocean, shows T. danae emitting blinding flashes of light from photophores on its arms as it attacks its prey. It is believed that this highly maneuverable squid uses the bright flashes to disorientate potential prey. These flashes may also serve to illuminate the prey to make for easier capture as well as a courtship and territorial display.[2]

As well as a predatorial characteristic, Dana bioluminescence has also been suggested to be a defense mechanism. Juveniles of this species have been observed moving rapidly in the direction of potential predators, as if hunting, to disorientate and startle the threat with a mock attack.[4]

In 2012, Taningia danae was filmed twice more during a search for the giant squid for the Discovery Channel Special, Monster Squid: The Giant Is Real.[5]

Still image from the first video footage of a live Taningia danae in its natural habitat.
Arms and buccal mass of T. danae

Remains of Dana octopus squid have, on occasion, been found washed ashore on beaches. In 2008, a mantle of T. danae was discovered by students in Bermuda's Grape Bay, while tentacle remnants were found further along the shore.[6] In early 2013, a 54 kg (119 lb) specimen with a length (excluding arms) of 103 cm (3.38 ft) was trawled at a depth of 240 m (790 ft) off the coast of Estaca de Bares, Galicia, Spain. It was loaned to the Spanish Institute of Oceanography.[7]

In popular culture[edit]

James Rollins' SIGMA Force Book 4: The Judas Strain (2007) provides detailed descriptions of sightings of schools of giant predatory squid in the waters off the island of Pusat[8] and graphic descriptions of collaboratortive squid attacks of several characters.[8][9] In the book's "Author's Note: Truth or Fiction: Fauna", Rollins shares: "As to our predatory squids, I based them on the species Taningia danae, which grow to six feet in length, hunt in packs, have brilliant light displays, and bear claws on their suckers. Definitely tough calamari."[10]

Notes[edit]

a.^ This is the weight of a specimen from the North Atlantic measuring 1.6 m (5.2 ft) in mantle length.[3] The previously reported maximum weight of 61.4 kg (135 lb) for T. danae (based on this same specimen) stems from a typographical error in the original paper[11] of Roper & Vecchione (1993).[3]

References[edit]

  1. ^ Nesis, K.N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. Light and Food Industry Publishing House, Moscow. 385+ii pp. (Russian) [Translated into English by B. S. Levitov, ed. by L. A. Burgess 1987. Cephalopods of the world. T.F.H. Publications, Neptune City, NJ. 351pp.]
  2. ^ a b Kubodera, T., Y. Koyama & K. Mori 2006. Observations of wild hunting behaviour and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae. PDF (295 KB) Proceedings of the Royal Society B: Biological Sciences 274(1613): 1029–1034. doi:10.1098/rspb.2006.0236
  3. ^ a b c Roper, C.F.E. & P. Jereb 2010. Family Octopoteuthidae. In: P. Jereb & C.F.E. Roper (eds.) Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 2. Myopsid and Oegopsid Squids. FAO Species Catalogue for Fishery Purposes No. 4, Vol. 2. FAO, Rome. pp. 262–268.
  4. ^ Young, R.E. & M. Vecchione 1999. Taningia danae Joubin, 1931. Version 1 January 1999. Tree of Life web project.
  5. ^ Monster Squid: The Giant Is Real. Discovery Channel.
  6. ^ Dale, A. 2008. "Monster from the Deep". Bermuda Royal Gazette, July 8, 2008.
  7. ^ Aparece en Galicia un calamar gigante de 54 kilos y más de un metro de largo. Europa Press, 11 February 2013. (Spanish)
  8. ^ a b Rollins, James (2007). SIGMA Force Book 4: The Judas Strain. p. 66. 
  9. ^ Rollins, James (2007). SIGMA Force Book 4: The Judas Strain. p. 46. 
  10. ^ Rollins, James (2007). The Judas Strain. p. Author's Note, p. 2. 
  11. ^ Roper, C.F.E. & M. Vecchione 1993. A geographic and taxonomic review of Taningia danae Joubin, 1931 (Cephalopoda: Octopoteuthidae), with new records and observations on bioluminescence. PDF In: T. Okutani, R.K. O'Dor & T. Kubodera (eds.) Recent Advances in Cephalopod Fisheries Biology. Tokai University Press, Tokyo. pp. 441–456.
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