Sanchez et al: Morphometry of juvenile and subadult Loligo pealei and L plei 



539 



minutes. The samples were then loaded and focused 

 for 3 hours at 2,000 V. The gels were fixed, washed 

 with destaining solution, and stained with Coomassie 

 Blue R-250. They were washed again in destaining 

 solution, dried, and photographed. Protein bands 

 from the juvenile and subadult squids were compared 

 with protein bands from the positively identified 

 adult specimens for species identification. 



Statistical analysis of data 



Two approaches were used in morphometric analysis 

 of data: comparisons were made between species and 

 by sex within each species. All data were analyzed with 

 Statgraphics Plus, Version 7.1 computer software. 

 Student's r-test ( a=0.05 ) was used to compare the means 

 of indices to determine if any index could be used to 

 distinguish between the two species or between sexes 

 within a species. Both linear and multiplicative regres- 

 sion techniques were employed to examine the rela- 

 tion of each measured character and each index (de- 

 pendent variable ) to mantle length ( independent vari- 

 able). Correlation coefficients (r) and coefficients of de- 

 termination (r 2 ) were calculated for each regression to 

 measure strength of the relationship and goodness of 

 fit of the calculated regression line, respectively. 



Coefficients of determination were considered high 

 when 85% of the total observed variability was ac- 

 counted for by the mathematical model. Tests were 

 conducted for differences in the slopes of the regres- 

 sion lines. The null hypothesis was that there was 

 no significant difference (a>0. 05) between the slopes. 

 A discriminant analysis was employed to identify the 

 relative contribution of measured characters or in- 

 dices, or both, in discriminating between the two 

 species. For each individual, the characters and in- 

 dices were entered with their respective species clas- 

 sification codes. Analyses were performed as follows: 

 1) all characters, 2) all indices, and 3) selected char- 

 acters or indices, or both (singly or in combination), 

 based on discriminant function coefficients. From 

 these analyses, characters or indices (or both), were 

 ranked by comparing their percentage success in 

 species differentiation. 



Results 



Biochemical analyses 



Isoelectric focusing patterns of mantle tissue proteins 

 are shown in Figure 3. Proteins used to differentiate 

 between the species were labeled a through /"accord- 

 ing to their decreasing order of isoelectric points 

 (Table 2). Both species had unique protein bands and 



were easily separated: bands a and b were unique to 

 L. plei and band e to L. pealei. Bands c, d, and /"were 

 shared by both species. 



General description of juveniles and 

 subadults 



In fresh specimens, the chromatophores of the mantle 

 generally are red in color in L. plei and brown in L. 



