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. An AVI format video clip of the Opsithoteuthis shown at the right is available at Cephalopods in Action.

Brief diagnosis:

A cirrate ...

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