FISHERY BULLETIN: VOL. 71, NO. 4 



remaining to be analyzed will not affect basic 

 conclusions to be drawn about the sensilla and 

 pores in Eiicalaiins. For purposes of this paper 

 nomenclatural recommendations have been lim- 

 ited to an essential minimum. The species I 

 recognize are summarized in Table 1. Aside 

 from the integumental organs and dorsal and 

 lateral views of the body, description of other 

 characters is restricted to a few basic features 

 (Figure 1). 



Functional significance aside, the diagnostic 

 qualities of body patterns of pores and sensilla 

 should be examined in the Copepoda on a broad 

 front. 



MATERIALS AND METHODS 



Systematic analysis of sensilla and pores was 

 carried out routinely on adult females of all 

 Eucala)iHS populations known to me (Table 1). 

 Numbers of specimens and collecting localities 

 are shown in Table 2. Sample size varied for 

 each species according to its geographical dis- 

 tribution, the overall frequency of variation, 

 number and arrangement of sensilla and pores, 

 and the availability of specimens. The number 

 of regularly occurring pores and sensilla on the 

 body of a specimen is large, ranging from 80 to 

 140 depending on the species, and their unvary- 

 ing arrangement in strongly patterned, bi- 

 laterally symmetrical arrays eliminated the need 

 for examining large numbers of specimens in 

 all but one case. Specimens were selected at 

 random from within each zooplankton sample, 

 but collecting localities were deliberately chosen 

 to represent the known distribution of the 

 species; i.e., as material on hand permitted 

 representative specimens of each species were 

 selected for examination from peripheral, inter- 

 mediate, and central localities. Observations on 

 adult males and on copepodite stages IV and V 

 were also made on all species but were ordinari- 

 ly limited to only two to four specimens each. 



Sensilla and pores are exceedingly difficult to 

 observe in Encalaiins using conventional light 

 microscopy without staining and clearing 

 specimens. Two simple methods were employed 

 in this study. One served in examining general 

 external features of the various types of sensilla 

 and their proximity to glandular pores. Speci- 



mens were immersed for about 24 h in a com- 

 bined clearing agent and stain, consisting of 9 

 parts lactic acid and 1 part of a 1% solution of 

 chlorazol black E (CBE) in 70% ethanol. Speci- 

 mens were then transferred directly to a drop of 

 glycerol on a glass slide for microscopic exami- 

 nation. 



More intensive clearing is necessary for 

 accurate and systematic tabulation of body pores 

 and sensilla. All tissue was removed from within 

 the integument by heating specimens in a 10% 

 aqueous KOH solution at 80° to 100° C for 2 to 4 

 h. Rapid boiling should be avoided to prevent 

 the integument from breaking apart. The ratio 

 of KOH solution to specimens was about 50 cc 

 per individual. The KOH digestion was re- 

 peated using fresh solution if precipitates or 

 fatty substances remained within the integu- 

 ment. The concentration of KOH has been in- 

 creased on occasion to 25% with satisfactory 

 results. For ease in viewing during micro- 

 scopic analysis, it is essential in preparing the 

 specimen to digest all tissues and eliminate 

 precipitates from within the integument. 



Following digestion the empty, still intact, 

 exoskeleton is prepared for staining by a rinse 

 in distilled water for 1 to 2 min and transfer to 

 70% ethanol for 1 to 2 min. These rinses should 

 be repeated if flocculent precipitates remain 

 within the integument. Immersion for about 

 30 sec in a solution of 1% CBE dissolved in 70% 

 ethanol stains specimens intensely. Staining 

 is terminated by flooding the preparation with 

 distilled water and transfer of the specimen 

 through a brief rinse in water to a drop of 

 glycerol placed on a glass microscope slide for 

 examination. Stained specimens suspended in 

 glycerol may be stored indefinitely in appro- 

 priate slide storage boxes. 



Washing and staining were carried out under 

 a stereomicroscope using 3-spot deep depression 

 slides and with solutions changed with the aid 

 of finely drawnout glass pipettes equipped with 

 rubber bulbs. Sensilla are usually lost in this 

 process, leaving the stained cuticle punctured 

 by clear perforations. Glandular i)ores also 

 appear as clear perforations permitting light 

 to stream through, but differ in shape and 

 appearance of the margin as described below 

 (p. 973). 



972 



