Although most investigators helieve that the luminescence during 

 "wheel" displays is produced by marine organisms in the water, it is 

 possible that some other type of luminescence may be occurring, if not 

 exclusively, at least as an adjunct to the bioluminescence. Of the 

 displays reported (Figure 'j) , most occurred in the following areas: 

 southern Persian Gulf, Strait of Hormuz, seaward of the Mouths of the 

 Indus, Strait of Malacca, Gulf of Thailand, and southern South China 

 Sea. Displays occurred to a lesser extent in the northern Andaman Sea 

 and along the north coast of Java. All of these regions are shallow, 

 and rather extensive blooms of phytoplankton occur in all quite" 

 regularly. The water often becomes supersaturated with oxygen during 

 these blooms. 



Strong pressure waves passing through a solution of high gas con- 

 tent may cause an electroluminescence due to the breakdown of bubbles 

 of gas within the solution. It is possible that this phenomenon may 

 occur in the sea also. Shock waves (from submarine earthquakes or 

 underwater volcanic activity), which often are strong enough to jolt 

 a ship, might also be strong enough to cause luminescence in sea water 

 containing a very high gas content such as may occur in this area. 



Although the occurrence of "phosphorescent wheels" or "waves" is 

 unpredictable at present and the reports are not numerous, the avail- 

 able records indicate that these phenomena are more frequent during 

 particular months in four areas. In the southern Persian Gulf -Strait 

 of Hormuz area about 67 percent of reported displays have occurred 

 from April through June. Off the Mouths of the Indus and in the Strait 

 of Malacca approximately 75 percent of reported displays have occurred 

 from July through December, and in the Gulf of Siam and the southern 

 South China Sea 75 percent of reported displays have occurred from 

 April through June and from September through December. 



POIAR REGIONS 



Although little information is available concerning biolumines- 

 cence in the ocean surrounding Antarctica, some rather strong spark- 

 type displays have occurred along the fringe of the Antarctic Con- 

 vergence. Here massive concentrations of euphausiids have been noted. 

 The light they give off may be intense at times but more often is weak. 



More bioluminescence has been observed in the ocean areas adjacent 

 to the Arctic Ocean, but information still is meager. Dinoflagellates 

 produce luminescence in the waters around Svalbard (Spitsbergen); 

 crustaceans also may create varying degrees of bioluminescence near 

 these islands. Tarasov (1956) reported an observation by K. S. 

 Badiginin in January 19^0 at Sloil'N, 3°50'E of bright greenish 

 "phosphorescence" lighting up the waves of an ice-filled ocean, rem- 

 iniscent of light observed in the Indian Ocean at a previous time. 



Ii3 



