FISHERY BULLETIN: VOL. 76. NO. 3 



Figure 15. — A. Photosensitive vesicles of Neoteuthis sp. B. 

 Photosensitive vesicles of Bathyteuthis abyssicola. Abbrevia- 

 tions as in Figure 2. 



third was taken in an opening-closing tow at about 

 750 m, and the fourth in an open oblique tow that 

 fished between 550 and 950 m. 



Photosensitive Vesicles (Figure 15B) 



The organs have been described in detail by 

 Young (1972a). One set of very large organs is 

 present. Each organ is located adjacent to the 

 posteroventral surface of the eye and above the 

 posterolateral edge of the funnel. Posterior to the 

 organ the skin is only lightly pigmented and forms 

 a "window." 



Family Ctenopterygiidae 



Ctenopteryx siculns (Verany 1851) 



Vertical Distribution (Figure 16A) 



Seven of eight specimens captured during the 

 day came from depths of about 625 to 800 m; the 

 other specimen came from about 925 m. At night 

 28 specimens were captured between depths of 25 

 to 260 m; over 807^ of the specimens were taken 

 between 50 and 150 m. 



FIGURE 17.— A. Photosensitive vesicles of 

 Ctenopteryx siculus. B. Photosensitive vesicles 

 ofOnychoteuthis compacta. IRID. S. — Iridophore 

 screen. Otherwise, abbreviations as in Figure 2. 



10 20 30 40 



MANTLE LENGTH, (n m 



40 70 

 MANTLE LENGTH. mm 



Figure 16. — A. Vertical distribution of Ctenopteryx siculus . B. 

 Vertical distribution oi Onychoteuthis compacta. Symbols as in 

 Figure 1. 



Photosensitive Vesicles (Figure 17 A) 



Ctenopteryx sicula has a single pair of large and 

 highly organized organs. Each organ consists of a 

 single elongate and flattened but curved vesicle. 

 Each organ extends from the posterior end of the 

 supraesophageal mass, beneath the optic stalk, 

 and anterior to the middle subesophageal mass 

 where it joins with its counterpart from the oppo- 

 site side. The organ, therefore, occupies a groove 

 between the central brain and the optic lobes. The 

 area where the two vesicles join lies just above the 

 funnel approximately at the point where the fun- 

 nel adductor muscles (bridles) attach to the 

 cephalic cartilage. An iridophore sheath is con- 

 tinuous and encloses both organs in this region, 

 but the vesicles do not actually fuse. That is, the 

 lumen of each vesicle remains separate. The vesi- 

 cles broaden slightly at their dorsal end and in the 

 region of the junction. The anterodorsal walls of 

 each vesicle are convex and lined with dense 

 layers of iridophores; light enters through the 



IRIDS 



594 



