Marine Biodiversity

, Volume 44, Issue 1, pp 151–155

The cephalopod Taningia danae Joubin, 1931 observed near bottom at over 2,000 m depth on Seine seamount

Short Notes

DOI: 10.1007/s12526-013-0197-9

Cite this article as:
Gomes-Pereira, J.N. & Tojeira, I. Mar Biodiv (2014) 44: 151. doi:10.1007/s12526-013-0197-9

Abstract

We report the first in situ observations of a large Taningia danae Joubin, 1931, close to the seafloor at bathyal depths of 2,157 m. The observation was made in the subtropical northeast Atlantic Seine seamount during daytime on 29 September 2012, over a silt-covered seafloor (33º40.1142′N, 14º22.7301′W). Seawater temperature was 4.2 ºC, salinity 35.40 ppt, oxygen saturation 50.87 Ox%, and pressure 2,178.29 dbar. Mantle length was estimated from imagery to be 65.3 cm (STD = 6.3). A repeated behaviour was observed every time the ROV approached: (1) swimming away from the ROV by flapping the fins twice (moving forward or backward), (2) gliding slightly inclined downward, until colliding against the seafloor, and (3) ascending obliquely or vertically in relation to the seafloor, finally evading the area moving upward using jet propulsion. These observations greatly extend the species depth range and document behaviour patterns. T. danae is able to explore beyond the mesopelagic zone where it has previously been reported.

Keywords

Octopoteuthis Seine seamount Bathyal Benthos ROV Behaviour 

Introduction

Taningia danae Joubin 1931 is one of the largest deep-water teuthiids, distributed worldwide in tropical to temperate oceans (Max ML = 170 cm; Clarke 1966; Nesis 1987; Roper and Vecchione 1993). Like the majority of oceanic teuthiids, the species is difficult to capture, and knowledge on morphology and biology has accumulated from scattered records and material collected from the stomachs of P. macrocephalus (Clarke 1967; Okutani and Satake 1978; Hoving et al. 2010).

In the early revisions by Clarke and Merrett (1972) and Clarke (1977), adult Taningia danae were expected to live beyond 1,000 m, based on the foraging depths of their predators. They were thought to become associated with, but not restricted to, the bottom (Clarke and Merrett 1972; Roper and Vecchione 1993). Small and juvenile individuals were collected by mid-water nets (Clarke and Lu 1974; Okutani 1974; Lu and Clarke 1975a, b), and Roper and Vecchione (1993) reported ontogenetic descents of juveniles from the surface to depths of 200–300 m (6–15 mm ML). Since then, direct evidence of adult distributions has been based on a small number of accidental bottom trawl catches (Roper and Vecchione 1993; Santos et al. 2001; Gonzáles et al. 2003), always less than 1,000 m depth. Only recently, Kubodera et al. (2007) attracted and recorded the behaviour of T. danae in the mesopelagic, revealing a powerful active predator, undertaking short distance diel vertical migrations, with a trend towards deeper mesopelagic layers during the day (around 600–900 m), ascending to shallower depths at night (around 240–500 m).

Video observations from a remote operated vehicle (ROV) at 2,157 meters has allowed us to extend the vertical distribution of T. danae by 1,000 m. Environmental parameters are given and the observations are described and interpreted in light of current knowledge.

Materials and methods

The species was video-recorded during an exploratory dive by the Task Group for the Extension of Continental Shelf (EMEPC; dive L12D16), with the working class ROV Luso model Bathysaurus XL, operated from R/V Almirante Gago Coutinho. Observations occurred on the Northeast Atlantic Seine seamount (33º40.1142′N, 14º22.7301′W), on 29 September 2012 at 15:10:25 hours.

Sighting location

Seine seamount rises steeply from more than 4,000 m to a summit plateau at 160–180 m. The species was observed on the southeastern slope at 2,157 m (Fig. 1), over an unconsolidated silt bottom. The surrounding seafloor was soft bottom, covered by silt and sand with scattered rocky outcrops. According to Bett et al. (2004), between 1,000 and 2,500 m the substrate is dominated by soft sediment with boulders (or bedrock) protruding through sediment overlay.
Fig. 1

Sighting location of Taningia danae observed near the bottom at Seine seamount on 29 September 2012, indicated by a x (3D image with 2 levels of exaggeration); inset location of Seine seamount in the central Northeast Atlantic (projections in ArcScene and ArcMap by R.Medeiros, IMAR-DOP/UAz)

Survey method

ROV Luso was developing geological and biological transects, sampling and transiting. The two halogen lights with 150 watts each and four HID lights with 7,500 watts each were on. The ROV travelled at an average speed of circa 0.5 m/s, at 0.5–1 m from the seafloor, providing a field of view between 3 and 5 m wide. Digital HD video was recorded and used to describe the species size and behaviour (observation time 00:01:15 hours). Measurements were made using two parallel scaling lasers distanced 60 cm apart projected on the seafloor, and the image analysis software ImageJ (1.46r). Water parameters were recorded in situ using a CTD, namely temperature, oxygen saturation, fluorescence, turbidity, pressure, and salinity (obtained from conductivity, temperature, and pressure; UNESCO 1981).

Results

A large Taningia danae was observed and recorded on video close to the bottom at Seine seamount by ROV Luso at 2,157 meters depth. In situ seawater temperature was at 4.23 ºC, salinity 35.40 ppt, oxygen saturation 50.87 Ox%, fluorescence 0.01 (μg/l), turbidity 0.08 (FTU) and pressure 21,78.29 dbar. Supplementary electronic video material is available online.

Species identification

The species was recognized by the triangular fins running along most of the dorsal mantle, the absence of tentacles, a large oval-shaped photophore on the tip of arm II and the absence of photophores in the tail (Nesis 1987). The photophore on arm II was similar to an eyelid, opening laterally, and glowing a bright white coloration as described by Roper and Vecchione (1993). Mantle length (ML) was estimated at 65.3 cm (STD = 6.3). No other measurements could be obtained from the imagery available. From the lack of tentacles and the ML, it was considered to be an adult (Nesis 1987; Roper and Vecchione 1993).

The ventral mantle was covered with silt by one third (Fig. 2b; less evident in 2c). The skin showed white spots equally spread on distal end of the dorsal surface of fins (Fig. 2c). Several non-pigmented areas were observed on the mantle, and on the ventral portion of the arms near the buccal crown.
Fig. 2

Taningia danae near the bottom at 2,157 m on Seine seamount (Northeast Atlantic); a (00:05 hours) rising obliquely moving backward and lifting dorsal arms after colliding against the seafloor; b flapping fins to move forward, and inset of closed fins, gliding; c side view of T. danae, with fins opening posteriorly to travel backwards and inset with detail of photophore glow; d collision against the seafloor and rising vertically; e jet propulsion and fusiform posture, evading the ROV and moving upwards

Notes on behaviour

Taningia danae was first observed just after colliding with the bottom (15:10:25 hours; Fig. 2a; see supplementary video). It follows a repeated behaviour of evasion of the ROV and collision against the seafloor, detailed in Table 1. Finally, it orientates vertically, ascending rapidly. From the duration and distance travelled gliding, without further flapping of fins, ca. 5 m, we estimated a minimum velocity of 0.39 m/s. For such a speed, the use of jet propulsion should have been used, even though no contraction of the mantle is evident from the imagery available.
Table 1

Behaviour of Taningia danae observed by ROV Luso at 2,076 m in Seine seamount

Hour

Time

Interaction

Behaviour

Fig.

Notes

15:10:25

0:00:00

Collision I

Observed rising from the seafloor, swimming backward (fin tip forefront) flapping fins twice

2a

Rising from seafloor partly covered in sediment

15:10:32

0:00:07

 

Glides (slightly obliquely upward)

-

 

15:10:46

0:00:14

Evasion I

Becomes close to the ROV, and flaps the fins twice propelling forward

2b

First fin flap to stop the backward motion, the second time gaining speed

15:10:47

0:00:23

 

Glides forward and slightly downward (2b insert)

2b

 

15:10:49

0:00:25

Collision II

Collides with seafloor, rises obliquely swimming backward

-

 

15:10:56

0:00:32

 

Glides backward

-

 

15:10:59

0:00:35

Evasion II

Close to the ROV flaps the fins twice, continuing backward movement

2c

Flashes photophore on third right arm

15:11:06

0:00:42

 

Glides backward

-

 

15:11:12

0:00:48

Collision III

Collides with seafloor, a and flap fins against seafloor

2d

 

15:11:17

0:00:53

Evasion III

Orientates vertically, raising dorsal arms and flapping its fins twice

-

Starts to ascend continuously with its fins closed

15:11:26

0:01:02

 

Glides vertically

2e

 

15:11:39

0:01:15

 

Leaves field of view

-

 

Discussion

Taningia danae is an elusive species for which knowledge has grown from isolated reports worldwide (Clarke 1967; Roper and Vecchione 1993; Sweeney 2001).

Occurrence in the North Atlantic

There are no previous records of T. danae from the Seine seamount. Small specimens have been captured throughout the Atlantic, particularly in the northeastern Atlantic (NEA), from where it was first described during 1921 Dana expedition near Cape Verde Archipelago (ML = 40 mm; Joubin 1931). NEA records extend from 11º to 57ºN, and numerous small-sized T. danae (<50 mm ML) have been caught by mid-water nets (e.g. Clarke and Lu 1974; Lu and Clarke 1975a, b). It is also an important sperm whale prey in the region, with an average of five beaks per sperm whale stomach sampled (Clarke 2006). In the vicinity of Seine seamount, small-sized species have been caught around Madeira Island (circa 32º30′–34º50′N, 16º–18ºW; Roper and Vecchione 1993; Clarke and Pascoe 1998; Clarke 2006; see references for details), as well as large specimens recorded from sperm whale stomachs sampled in Madeira (Clarke 1962).

Behaviour

The behaviour observed during this rare event revealed an active cephalopod in good condition. As a large oceanic predator, we assume such observations were only possible because the specimen was attracted to the ROV, as observed on other occasions. The swimming behaviour, in particular the movement of fins, was as described by Kubodera et al. (2007). Our observations show, however, an energetically more conservative swimming pattern, using fins twice followed by gliding. This was not noted on the hunting behaviour observed by Kubodera et al. (2007), where fins were used actively several times while moving towards prey.

The repeated collisions against the seafloor are intriguing, as they contrast with the high swimming abilities reported for adults in the mesopelagic under dark lights (Kubodera et al. 2007). T. danae has been observed approaching ascending/descending ROVs in the open mesopelagic, maintaining good manoeuvrability under lighting systems. However, there are several records of theuthiids crashing against the seafloor due to the ROV lights. Pelagic cephalopods are also known to have a more limited locomotor efficiency with increasing depth (Seibel et al. 1997).

Acknowledgments

Malcolm Roy Clarke, for keeping our dreams of squid alive. The authors wish to acknowledge the ROV pilots, also Miguel Souto and all the Task Group for the Extension of Continental Shelf (EMEPC). J.N.G.P. was supported by the doctoral grant from the Regional Directorate for Education, Science and Culture, of the Regional Government of the Azores (M3.1.2/F/062/2011). LARSyS-Associated Laboratory no. 9 funded by the Portuguese Foundation for Science and Technology (FCT) through pluriannual and programmatic funding schemes (OE, FEDER, POCI2001, FSE) and by the Azores Directorate for Science and Technology (DRCT).

Supplementary material

ESM 1

(MPG 26042 kb)

ESM 2

(MOV 6266 kb)

Copyright information

© Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Centre of IMAR and Department of Oceanography and FisheriesUniversity of the AzoresHortaPortugal
  2. 2.LARSyS – Associated Laboratory for Robotics and Systems in Engineering and ScienceLisboaPortugal
  3. 3.Portuguese Task Group for the Extension of the Continental Shelf (EMEPC)Paço de ArcosPortugal

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