BIOLOGY OF SPIRULA 67 



TABLE 3 



Analysis of Dana Catches From Stations in the West Indies of 



Depths Less Than 1000 Meters. Temperature Observations 



From Dana Stations in the Area. 



In Table 3 I have analyzed the Dana catches from stations of depths 

 less than 1000 meters in the West Indies (published in 1943), and given 

 the temperature observations from Dana stations in the area (Hydro- 

 graphical observations 1937). The actual depth of the pelagic nets was 

 supposed to be about one third of the wire length. Here again the upper 

 temperature range is near 20° C, while the lower catches were made at 

 temperatures above 14° C. This means that all the specimens must have 

 been caught well within the thermosphere, but about 200 meters or more 

 below the surface. It should be pointed out that all hauls were made 

 during the night, at which time any mesopelagic animal would be expected 

 to occur at its normal upper range. 



At Dana Station 3786 VIII in the Celebes Sea (depth 970 meters) 

 a specimen was caught in a 2 meter stramin-net with 800 meters of wire 

 out, which would indicate a maximum fishing depth of about 270 meters. 

 The temperatures of a nearby station (3784) showed 11.9° C. at 200 

 meters, 10.1° C. at 300 meters and 4.0° C. at 1000 meters. 



With these observations in mind, I have given the distribution of 

 Spirula together with certain isotherms. The 10° C. surface isotherm has 

 been drawn to show the polar limits of the thermosphere. The numerous 

 hauls made all over the North Atlantic by many expeditions should be 

 sufficient to show that the 10° C. surface isotherm, as expected, gives 

 no clue to the distribution pattern. The 10° C. isotherm at 400 meters. 



