Teuthowenia megalops Prosch 1947

Introduction

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Figure. Two superimposed images of the same specimen of T. megalops, about 140 mm ML, showing lateral attachment of the fin and the very large eyes. Top - Side view. Bottom - Dorsal view. Captured aboard the R/V G. O. SARS during the MARECO cruise to the central North Atlantic.

Characteristics

1. Mantle
   1. Single-point tubercle, rarely absent, at each funnel-mantle fusion.
      

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      Figure. Ventral view of the tubercle at the funnel-mantle fusion of T. megalops. Left - Mature male, 199 mm GL. Drawing from Voss, 1985, pp. 17, 18. Right - White arrow points to tubercule. Photograph by R. Young.
      

2. Arms
   1. Arms II of males with 2 series of suckers on modified tips (sometimes appearing as 3-4 series due to crowding).
      

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      Figure. Oral view of the modified tip of arm II of T. megalops which occupies 23-32% of the arm length. Immature male, 184 mm GL. From Voss, 1985, pp. 17, 18. Printed with the Permission of the Bulletin of Marine Science.

   2. Arms II of males with 15-19 pairs of normal suckers proximal to modified tips.
   3. Arms I of males without modified tips.
      

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      Figure. Oral view of the entire arm I of a mature male of T. megalops (199 mm GL) showing sexual modifications but without modified tip. From Voss, 1985, pp. 17, 18.
      

   4. Largest arm III suckers 3 times basal suckers in diameter (at least 2.0-2.8% of GL in diameter).
      
3. Tentacles
   1. Largest club suckers with 19-24 teeth.
      

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      Figure. Oral view of the largest sucker from the club manus of T. megalops, female, 187 mm ML. Drawing from Voss, 1985, pp. 17, 18.

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

Comments

Additional details of the description of T. megalops can be found here.

Life history

The paralarval period ends when the eyes become sessile between sizes of 75 and 95 mm GL. Paralarvae have relatively large, oval and widely spaced chromatophores on the mantle. The tubercle first appears at the funnel-mantle fusion at a size between 30 and 60 mm GL (Voss, 1985).

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Figure. T. megalops growth stages. Left - Two views of a paralarva photographed in a shipboard aquarium: side view, and an anterior view with the head and arms withdrawn into the mantle cavity. Also, in the latter photograph the squid had released ink into the mantle cavity. © . Right - (left to right): 11 mm ML, 29 mm ML, 60 mm ML. Drawings from Voss, 1985, p. 22.

Distribution

Vertical distribution

Lu and Clarke (1975) found the paralarval stages mostly in the upper 200 m.

With one exception at 400m, Voss (1985) found all maturing females and mature and near-mature males at depths of 1000 - 2700 m.

Geographical distribution

T. megalops occupies the productive waters of the subarctic and northern temperate Atlantic Ocean where it lies within the Northern Subpolar-Temperate faunal zone (Voss, 1985).

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Geographical distribution map modified from Voss, 1985.

References

Lu, C. C. and M. R. Clarke, 1975. Vertical Distribution of Cephalopods at 40° N, 53°N and 60°N at 20° W in the North Atlantic. Journal of the Marine Biological Association of the United Kingdom, 55 (2): 143-163.

Vecchione, M. Young, R. E. and U. Piatkowski. 2010. Cephalopods of the northern Mid-Atlantic Ridge. Marine Biology Research, 6: 1, 25-52.

Voss, N. A. 1980. A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci. 30: 365-412.

Voss, N. A. 1985. Systematics, biology and biogeography of the cranchiid cephalopod genus Teuthowenia (Oegopsida). Bull. Mar. Sci. 36: 1-85.