Opisthoteuthidae Verrill 1896

Introduction

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Figure. Opisthoteuthis agassizii (?) on the bottom (video frame). JSL II dive 1746; 25 April 1989; St. Vincent I.; depth = 586 m; temp. = 6.6°C (from Vecchione and Roper, 1991).

The body of these octopods is foreshortened along the anterior/posterior axis. The foreshortening is extreme in Opisthoteuthis which is known as the "flapjack" (pancake) devilfish due to its flattened appearance. The secondary web is absent. The radula is reduced or absent apparently reflecting the habit of swallowing prey whole (Aldred, et al., 1983). The cirri are short when compared to those of the Cirroteuthidae. Most opisthoteuthids alternate between sitting on the ocean floor and swimming just above it (e.g., Peyera, 1965). Opisthoteuthis swims mainly by contraction of the arm-web complex while Grimpoteuthis uses primarily powerful fin strokes to swim (Vecchione and Young, 1997). Some opisthoteuthids (species of Luteuthis and some species of Grimpoteuthis) apear, judging from their very gelatinous consistency, to be entirely pelagic.

A video introduction Opisthoteuthis is seen here.

Brief diagnosis:

A cirrate ...

• with body axis strongly compressed in anteroposterior plane.
  
• with simple U- or W-shaped shell.
  

Characteristics

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Figure. Oral view of arm of Grimpoteuthis bathynectes, showing web nodule (arrow). Drawing modified from Voss and Pearcy, 1990.

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Figure. Left to right - Opisthoteuthis grimaldii shell (U-shaped), stained, photographed by R. Young; Cirroctopus glacialis shell (V-shaped, Cirroctopodidae), stained, photographed by R. Young; Luteuthis shuishi shell (W-shaped), photograph from O'Shea and Lu, 2002.

1. Shape and consistency
   1. Body axis anterior-posteriorly compressed (shell reaches, or nearly reaches, posterior end of body; i.e., no gelatinous extension of the body exists posterior to the shell).
      
      
2. Arms and web
   1. Suckers and cirri extend to tips of arms.
   2. Secondary web absent.
   3. Web nodules (= web support) present (arrow) in some genera.
   4. Suckers unmodified.
      
      
3. Cirri
   1. Cirri short (length 0.4 - 2.5 times diameter of largest sucker).
      
      
4. Shell
   1. Simple U- or W-shaped.
   2. Lateral wings not expanded or only slightly expanded.
      
      
5. Pigmentation
   1. Areolar spots present (arrow) in some genera.

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Figure. Side view of a young Opisthoteuthis albatrossi showing areolae (arrow). Drawing modified from Sasaki, 1929.

Nomenclature

O'Shea (1999) described a new genus, Enigmatiteuthis, which he placed in his family Grimpoteuthidae. He also placed Grimpoteuthis wulkeri, G. bathynectes and G. pacifica in his new genus. Collins (in press) in his examination of the North Atlantic species of Grimpoteuthis concluded that species of Enigmatiteuthis should be placed in Grimpoteuthis (i.e., Enigmatiteuthis is a junior synonym of Grimpoteuthis).

Collins and Villanueva (2006) place Grimpoteuthis, Cryptoteuthis and Luteuthis in the family Grimpoteuthidae O'Shea, 1999. Their diagnosis of the Grimpoteuthidae is:

"Medium-to-large sized, bell-shaped cirrates with lateral fins. Web deep and simple. Shell U-shaped, with lateral walls parallel. Optic nerve passes though white body in single bundle. Radula reduced or absent. Posterior salivary glands reduced or absent. Cirri of short to moderate length. Gills of ‘half-orange’ form."

This change leaves the Opisthoteuthidae with a single genus, Opisthoteuthis.  Collins and Villanueva (2006) define this view of the Opisthoteuthidae as follows:

"Moderate-sized cirrates with small, subterminal fins. Shell a flaring U-shape, lateral walls tapering to fine points. Optic nerves pass through white body in two to four bundles. Two fields of enlarged suckers in mature males. Digestive gland entire or bilobed. Radula and posterior salivary glands absent. Web deep, single. Gills of ‘half-orange’ form."

The rationale for the ToL classification is given on the Cirrata page.

References

Aldred, R. G., M. Nixon and J. Z. Young. 1983. Cirrothauma murrayi Chun, a finned octopod. Phil. Trans. Roy. Soc. Lond., 301: 1-54.

Nesis, K. N. 1982/87. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In 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.

O'Shea, Steve. 1999. The Marine Fauna of New Zealand: Octopoda (Mollusca: Cephalopoda). NIWA Biodiversity Memoir 112: 280pp.

O'Shea, S. and C. C. Lu. 2002. A New Species of Luteuthis (Mollusca: Cephalopoda: Cirroctopoda) from the South China Sea. Zoological Studies, 4: 119-126.

Pereya, W. T. 1965. New records and observations on the flapjack devilfish Opisthoteuthis californiana Berry. Pacif. Sci., 19: 427-441.

Voss, G. L. 1988. Evolution and phylogenetic relationships of deep-sea octopods (Cirrata and Incirrata). P. 253-276. In: Clarke, M. R. and E. R. Trueman (Eds.). The Mollusca. Vol. 12. Paleontology and Neontology of Cephalopods. Academic Press, New York. 355pp.

Voss, G. L. and W. G. Pearcy (1990). Deep-water octopods (Mollusca: Cephalopoda) of the Northeastern Pacific. Proc. Calif. Acad. Sci., 47: 47-94.

Vecchione, M. and C. F.E. Roper. 1991 Cephalopods observed from submersibles in the western North Atlantic. Bull. Mar. Sci., 49(1-2):433-445.

Vecchione, M. and R. E. Young. 1997. Aspects of the functional morphology of cirrate octopods: locomotion and feeding. Vie Milieu 47(2):101-110..