drift together or by which upwelling increases surface nutrients and 

 thereby increases the production of marine forms capable of luminescing 



The percentages of total observations for the three types of dis- 

 plays in this region are as follows: 



Sheet type 75^ 



Spark type 3^ 



Glowing-ball type 225^ 



The light given off by the sheet- type displays often is glaring in 

 intensity and much more spectacular than any reported from other ocean 

 areas of the world. 



Some of the more unusual reports on surface bioluminescence are 

 from the Arabian Sea. Numerous patches of vivid bioluminescence were 

 noted on the surface of the sea by observers on the SS ELPHEWQR in 

 September 1931 • The patches seemed to be arising from the depths of 

 the ocean; the water swirled as if in an upward and spiral movement. 

 Later in the evening, it was found that a ray of light from a flash- 

 light could produce bioluminescence in the water wherever shown. Ob- 

 servers on board the USS DEVON in December 1929 noted small patches of 

 bioluminescence which suddenly expanded from diameters of about 6 feet 

 to diameters of 100 to UOO feet. In April 195^ observers on board the 

 MV DAGMAR SALEN noted a similar appearance to that of the crew of the 

 DEVON. The luminescence appeared to "bubble" up from below in the 

 form of a cone of light, which eventually spread out to a diameter of 

 100 to 150 years. Those on board the DAGMAR SALEN also observed the 

 water begin to "boil" because of thousands of mackerellike fish. One 

 authority believes this occurrence to be a rare occasion when the Deep 

 Scattering Layer broke through to the surface, as the mass appeared to 

 be made up of luminescent plankton and the fish feeding upon them. 



A "milky sea" display was noted by observers on board the Greek 

 vessel SS lONNIS ZAEIRAKIS in August I95O in the Arabian Sea. Second 

 Officer M. Mariakis reported that the horizon commenced to whiten as 

 the ship approached the luminous region, and then within the luminous 

 region the water assiimed a milky color. The discoloration of the 

 water was considered different from "phosphorescence" by the reporter. 

 The phenomenon lasted about k^ hours, and during that time the lower 

 layers of the atmosphere acquired a very thin whitish appearance, 

 reaching approximately 15° altitude and dimming the brilliance of the 

 stars. The sea -i^ms rough until the ship reached the luminous area, 

 where it became calm and glassy. This change may have been the result 

 of concentrations of oil-bearing luminescent organisms such as 

 Noctiluca . Captain A. Charasakis of the Greek vessel VERNICOS NICOLAS 

 in the Arabian Sea during August 19^9 observed that the "whole surface 

 of the sea became brightly and deeply fluorescent" and "the surface 

 appeared as if crystalline in nature, through which a high tension 

 current of electricity passed, illuminating it brightly." Visibility 



37 



