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Containing group: Sthenoteuthis

Characteristics

1. Arms
   1. Hectocotylus with 22-26 suckers.
      
   

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   Figure. Hectocotylus of Sthenoteuthis pteropus. Drawing from Roeleveld (1998).
2. Tentacles
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   Figure. Oral views of the left and right tentacle bases of S. pteropus showing the relationship between the carpal knobs (colored yellow) and the number of more proximal suckers. Note that the proximal carpal locking-sucker is absent from the tentacle on the right. Drawing modified from Pfeffer (1912).
3. Funnel/mantle locking-apparatus
   1. Funnel and mantle components not fused.
      
   

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   Figure. Frontal views of the funnel (left) and mantle (right) components of the funnel/mantle locking-apparatus of S. pteropus showing the absence of any tearing of the cartilage and therefore an absence of fusion of the two components. Photographs by R. Young.

   2. Photophores
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         Figure. Ventral view of the subcutaneous photophores of S. pteropus. Diagramatic illustration from Roper (1963).

Life History

S. pteropus spawns primarily in specific regions on either side of the tropical Atlantic (Zuev and Nikolsky, 1993).  A detailed study from the tropical Atlantic, found paralarval growth of S. pteropus is comparable to that of O. bartramii (ie, ca 7 mm ML at 30 days????) and proboscis separation in S. pteropus occurred at a ML of 8.5 mm and an age of 33-35 days (Arkhipkin and Mikheev, 1992). In this study, based on statolith examination, they recognized a "dark zone" in the statolith characterized by the lower transparency of the statolith and the width of the increments. They found that this period ended at about 100-110 days at a ML of about 100 mm which they considered to be the end of the juvenile period for S. pteropus.

References

Arkhipkin and Mikheev. 1992.

Pfeffer, G. 1912. Die Cephalopoden der Plankton-Expedition. Ergebniss der Plankton-Expedition der Humboldt-Stiftung. 2: 1-815.

Roeleveld, M. A. 1988. Generic interrelationships within the Ommastrephidae (Cephalopoda). P.277-314. In: M. R. Clarke and E. R. Trueman (eds.). The Mollusca. Vol. 12. Paleontology and Neontology of Cephalopods. Academic Press, N.Y., 355pp. (with permission from Elsevier).

Roper, C. F. E. 1963. Observations in Ommastrephes pteropus (Steenstrup, 1855), with notes on its occurrence in the family Ommastrephidae (Mollusca: Cephalopoda). Bull. Mar. Sc., 13: 343-353.

Zuev and Nikolsky. 1993.