BATHYPELAGIC SQUID BATHYTEUTHIS 161 



be attributed to the low to minimum productivity of these regions. 

 This condition would account for the discrepancies between the poor 

 success of the extensive exploratory fishing efforts in the West Atlantic 

 and the high success of the small exploratory fishing effort, in the East 

 Atlantic, especially in the tropical region. Moreover, this may be an 

 example of the exclusion of a species from an area that has the proper 

 physicochemical oceanographic conditions (e.g., the Caribbean) but 

 lacks proper biological conditions. 



The comments in the preceding oceanographic section concerning dis- 

 tribution in the water masses that presently are not known to contain 

 Bathyteuthis are also applicable to the discussion of distribution with 

 productivity, Bathyteuthis may be expected to inhabit the oceanic re- 

 gions that combine the optimal oceanographic conditions and high 

 productivity. In addition, Bathyteuthis may well occur in regions 

 where more influential factors, e.g., productivity and temperature, 

 are optimal and outweigh suboptimal conditions of less important 

 factors. For instance, Bathyteuthis may occur in North Pacific Inter- 

 mediate Water where the salinity generally is below the normal range 

 (34.5%o) but temperatures are within range and productivity is high. 

 Areas of low or minimum productivity, e.g., the Central Water masses, 

 also generally do not have oceanographic conditions that are suitable 

 for Bathyteuthis. Conditions within the acceptable range for Bathyteu- 

 this are met in some transitional areas (e.g., bordering the southern 

 Central Water masses of the three oceans) where productivity is mod- 

 erate. Otherwise, it appears that Bathyteuthis does not occur in re- 

 gions of poor organic production regardless of the physicochemical 

 properties. 



Each water mass has diagnostic biological characteristics (e.g., in 

 organic production and faunal composition) as well as unique tem- 

 perature-salinity characteristics. The T-S relationships, and other 

 physicochemical phenomena such as current systems, vertical mixing, 

 enrichment of surface waters with nutrient salts, and insolation, may 

 characterize or index the resultant biological elements or productivity 

 and food supply that are the primary limiting factors. Ebeling (1962) 

 and Marshall (1963) have emphasized that these biological factors 

 have significance as isolating mechanisms in the deep-sea fauna. 



Ebeling found that distributions of species of Melamphaes generally 

 follow the water masses and that when they depart from this it is 

 to follow the contours of productivity. Moreover, four species that 

 occur in Central Water masses of low food supply are dwarf species, 

 while seven species found in productive waters are giants. And within 

 one species, Melamphaes jana£^ which has a disjunct distribution, the 

 adults in the eastern Pacific are considerably larger than adults in the 



