YOUNG: VERTICAL DISTRIBUTION AND PHOTOSENSITIVE VESICLES 



10 



20 



30 



iO 50 60 70 



VANTLE LENGTH, mm 



80 



90 



170 



Figure 13. — Vertical distribution of Histioteuthis dofleini. 

 From Young (1975c). Symbols as in Figure 1. 



night, the range is 100 to 500 m; over 85^7^ of the 

 captures came from depths of 150 to 300 m. During 

 both the day and night, larger individuals tend to 

 be found at slightly greater depths. 



20 40 60 



MANTLE LENGTH, mm 



:o 40 60 



MANTIE tENGTH.ww 



Figure 14. — A. Vertical distribution oi Histioteuthis celetaria 

 pacifica (triangles) and Histioteuthis sp. (circles). B. Vertical 

 distribution oi Bathyteuthis abyssicola. Symbols as in Figure 1. 



Photosensitive Vesicles (Figure 12B) 



Histioteuthis dofleini has two sets of vesicles, a 

 dorsal and a ventral set, joined by a narrow strand 

 of vesicles. The dorsal and ventral organs are flat 

 and approximately the same size. The dorsal or- 

 gans lie dorsal to the optic lobes, and the ventral 

 organs lie above the lateral bases of the funnel 

 (R. E. Young 1977). 



Histioteuthis celetaria pacifica 

 (Voss 1962) 



Vertical Distribution (Figure 14A) 



A single day capture came from 550 m. Four 

 night captures came from depths of about 250 to 

 400 m. 



Photosensitive Vesicles 



The vesicles are similar to those of//, dofleini 

 except that the dorsal and ventral organs are more 

 compact. 



Histioteuthis sp. 



Vertical Distribution (Figure 14A) 



Two day captures came from depths of 575 and 

 665 m, and four night captures were made be- 

 tween depths of 165 and 275 m. 



Photosensitive Vesicles 



The vesicles are as in //. dofleini. 



Neoteuthis sp. 



Vertical Distribution 



A single small specimen was taken in an IKMT 

 tow that fished between the surface and 350 m at 

 night. Roper and Young (1975) reported nine 

 specimens from the Atlantic Ocean taken in open 

 tows between 1,300 and 2,000 m at night and one 

 specimen taken in a closing net at 900 m at night. 



Photosensitive Vesicles (Figure 15A) 



Neoteuthis sp. has only one set of organs. Each 

 organ consists of a small grapelike cluster of 

 globular vesicles arising from the medioposterior 

 surface of the peduncle lobe and extending ven- 

 trally below the optic stalk. 



Bathyteuthis abyssicola Hoyle 1885 

 Vertical Distribution (Figure 14B) 



Five of six specimens captured during the day 

 were taken between 700 and 975 m. The remain- 

 ing specimen was taken in an oblique IKMT tow 

 that fished between 1,100 and 1,900 m. At night, 

 two specimens were taken in the upper 400 m, a 



593 



