BATHYPELAGIC SQUID BATHYTEUTHIS 41 



diictive waters of the East Pacific, Atlantic, and Indian Oceans. 

 Ranges between 300 and 3000 m, mostly 1000-2500 m (see Part II). 



Morphometry. — Measurements of various body parts have been 

 made to determine allometric relationships and variability of propor- 

 tions that occur in Bathyteuthis abyssicola during growth. All meas- 

 urements are compared with the standard of size, the mantle length, 

 which is plotted as the abscissa. Measurements were made on 121 speci- 

 mens of B. abyssicola from the Southern Ocean. These specimens rep- 

 resent about one-fourth of the total sample population that was avail- 

 able at this stage of the study ; the sample consists of 53 males and 68 

 females of all available sizes taken throughout the study area. The 

 following measurements were made : mantle length, mantle width, 

 head length, head width, basal fin length, total fin length, fin width, 

 tentacle length, club length, arm lengths (I-IV). The values of these 

 measurements are plotted as the ordinate against mantle length on 

 scatter diagrams (figs. 1 to 13) . 



The plots of all of the characters, with the exception of tentacle 

 length and club length, show little spread in the values, and the rela- 

 tions of mantle length to the other variates appear to be linear. The 

 broader spread of points on the scattergrams for tentacle length espe- 

 cially and less so for club length (figs. 7, 8) reflects a condition of 

 preservation rather than of irregular or unordered growth. The elastic 

 tentacles are subject to contraction or stretching, depending on the 

 condition of the specimen at fixation. Even so, a more or less linear 

 growth is indicated for the tentacles (fig. 7). Clubs make up a small 

 proportion of tentacle length so they do not readily show the effects 

 of preservation. 



Club length vs. tentacle length is plotted (fig. 9) ; a linear relation- 

 ship is indicated here, too, although in the extreme upper and lower 

 range of sizes club lengths appear to be plateaus. These may be a result 

 of the conditions of preservation, or they may reflect a natural sig- 

 moidal pattern of growth. 



Allometric growth appears to occur as a general feature in the 

 squids that have been studied in this regard. Chiroteuthis exhibits an 

 extreme growth pattern in which drastic changes in proportions occur 

 between the "Doratopsis'' stage and adulthood. Also, Adam (1952, p. 

 63) has demonstrated that the fins and ventrolateral arms of males of 

 Alloteuthis afncana, cease to grow allometrically above a certain size 

 (age). In B. ahyssicola the allometric relationships of mantle width, 

 head width, and fin width, for example, may be slightly altered at the 

 maximum size of the species, although too few very large sj^ecimens 

 are available currently to substantiate this. Therefore, within the ex- 

 tent of these data, B. ahyssicoki exhibits well-defined allometric growth 

 curves. 



