Ornithoteuthis Okada 1927

Introduction

These are relatively small (about 100-200 mm ML) and highly agile ommastrephids that do not seem to be common anywhere. Their taxonomic characteristics are very different from other members of the subfamily.

Brief diagnosis:

An ommastrephin ...

• with mantle and fins drawn out into a narrow tail.
  
• with luminous stripe along midline on viscera.
  

Characteristics

1. Tentacles
   1. Arms tips in subadults not unusually attenuate; arms I with 25-30 pairs of suckers (Wormuth, 1976).
   2. Carpal locking-apparatus absent from tentacles (unique in subfamily).
      
   3. Largest club suckers with ca. 20 uniform, broadly spaced, small teeth (unique in subfamily).
   

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   Figure. Oral view of the inner sucker ring of a large club sucker from Ornithoteuthis volitalis. Drawing from Roeleveld (1988).
2. Funnel
   1. Mantle component of the funnel/mantle locking-apparatus without anterior bifurcation.
   2. Funnel groove with foveola, with or without side pockets.
      
      
3. Mantle
   1. Mantle slender, drawn out into narrow tail (unique in subfamily).
      
      
4. Fins
   1. Fins narrowly drawn out along tail.
      
      
5. Photophores
1. Small subcutaneous photophores absent. Absence of large or small subcutaneous unique in subfamily).
   
2. Luminous patch present on ventral surface of each eye.
3. Visceral photophores present: two intestinal photophores and an elongate luminous stripe along midline on viscera (unique in family).


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Figure. Photophores of Ornithoteuthis antillarum. Left - Ventral view of the mantle cavity of showing the visceral photophores. Left arrow points to an elongate luminous strip. Right two arrows point to intestinal photophores. Note that the anterior visceral photophore appears to have a different structure than the posterior one. Right - Ventral view of the head of the same squid showing the ocular photophore on the right eye. Photographs by M. Vecchione.

Comments

Comparison of species (Dunning, 1998):

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Figure. Ventrolateral and oral views of the hectocotylus of Ornithoteuthis spp. Top - O. volatilis. Drawing from Roeleveld (1988). Bottom - O. antillarum. Drawing from Voss (1957). Unfortunately the specific differences in hectocotylus structure are not well illustrated by these figures.

Distribution

References

Dunning, M. C. 1998. A Review of the systematics, distribution, and biology of the arrow squid genera Ommastrephes Orbigny, 1835, Sthenoteuthis Verrill, 1880, and Ornithoteuthis Okada, 1927 (Cephalopoda: Ommastrephidae). Smiths. Contr. Zool., No. 586: 425-433.

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.

Sasaki, M. 1929. A Monograph of the Dibranchiate Cephalopods of the Japanese and Adjacent Waters. Journal of the College of Agriculture, Hokkaido Imperial University, 20(supplement):357 pages.

Voss, G.L. 1957. Observations on Ornithoteuthis antillarum adam, 1957. An ommastrephid ssquid from the West Indies. Bulletin of Marine Science of the Gulf and Caribbean, 7(4):370-378.