BATHYPELAGIC SQUID BATHYTEUTHIS 141 



the lower limit of distribution of this species is governed by the 10° 

 isotherm that generally lies at 400 m ( more or less) over the geographic 

 range of Spirula. Bruiin's earlier work had set the depth limit of 

 Spirilla at 1750 m. Thore (1949) examined the distributions of the 

 Dana pelagic octopods, particularly of JapeteUa dmphwfia. The verti- 

 cal distributions were determined principally by Bruun's method of 

 statistical analysis of depths of captures; the distribution of /. dia- 

 pfuina was defined by parameters of temperature, salinity, and pro- 

 ductivity. Pickford (1946) was the first to study the distribution of a 

 marine animal in relation to the T-S characteristics of water masses; 

 she plotted the distribution of Vampyroteuthls i/if emails on T-S dia- 

 grams and determined that density is the common factor governing 

 the distribution of this species. 



Most workers (e.g., Haffner, 1952; Bieri, 1959) have plotted only 

 the points of capture on T-S diagrams, but Sund (1961, 1964) , Ebeling 

 (1962), and Ebeling and Weed (1963) have constructed T-S curves 

 for each capture (over the determined vertical range of each species) 

 and have plotted these in the water mass envelopes. This method more 

 precisely defines the water column and the water mass in which the 

 species were captured. Backus, Mead, Haedrich, and Ebeling (1965), 

 using a different approach, have presented a statistical method of 

 determining faunal boundaries between or wdthin water masses. 



A large amount of material from a number of locations plus con- 

 current oceanographic and capture data are needed to determine prop- 

 erly the distribution of a species in relation to the physicochemical 

 parameters of its environment. These requirements are easily met for 

 Bathyteutlik abysslcohi from the Antarctic Ocean, but for this species 

 from the Atlantic and eastern Pacific and for B. hacldlfera the data 

 are less complete. Nevertheless, it is possible to make some fairly defini- 

 tive statements concerning the distribution of Bathyteuthis. 



Antarctic Ocean 



Figure 43 is the T-S capture diagram for specimens taken by the 

 Eltanln in Antarctic waters. Capture points rather than capture curves 

 are used because of the uniform nature of the water masses in the 

 Antarctic region. The vertical component of the plot represents 

 Antarctic Circumpolar Water of high salinity and low temperature 

 and Lower Deep Water of the same characteristics and at greater 

 depths. Most of the points plotted below 1°C are from the Atlantic 

 sector of the Antarctic Circumpolar Water Mass while the points 

 above 1°C are from the Pacific sector and the Drake Passage. Five of 

 the deepest captures from the Peru Current, representing Deep Water, 

 are also included in the vertical component of the plot. The area where 



