TIME (ED.T) 

 1800 



PRE-ECLIPSE 

 1703 



ECLIPSE POST-ECLIPSE 



1755 1903 





 10 

 20 





 10 



2 20- 



I 

 t— 

 a. 



UJ 



Q 

 10 

 20- 



Pseudocolonus minutus 



PRE-ECLIPSE 

 JULY 20 



POST-ECLIPSE 



Acortia longiremus 



PRE-ECLIPSE 

 JULY 20 



POST-ECLIPSE 



50 50 50 50 



PERCENT OCCURRENCE 



50 50 



Figure 5. — Depth distribution of two species of cope- 

 pods before, during, and after the eclipse. 



forms, but showed no appreciable change in 

 distribution during the eclipse. Though more 

 frequent sampling might have established a 

 basis for understanding these differences, it is 

 evident that all species did not respond in the 

 same degree or in the same manner. 



The lack of uniformity among species and 

 within species was not peculiar to the eclipse 

 study. Wynne-Edwards (1962) summarized 

 several early works which demonstrated the 

 differences in behavior of copepods. Clark 

 (1933 and 1934) discussed diurnal changes in 

 vertical distribution relative to sex and age- 

 groups and reported the stronger migratory 

 habits of adult female C. fi)imarchicus, which 

 rose much nearer to the surface at night than did 

 the male. During the eclipse, female A. longi- 

 remus were more active than males and were 

 more prevalent at the surface (fig. 6). There 

 was a suggestion of a reversal of this phe- 

 nomenon in P. minutus, and no difference in 

 the distribution of sexes in T. longicornis. Dur- 

 ing the eclipse of 1954, Petipa (1955) reported 

 that vertical migration in the Copepoda was 



Or 



S 



X 



I— 



LiJ 



Q 



Acortia longiremis cf> 



Acortia longiremis o 



100 50 50 100 

 PERCENT OCCURRENCE 



Figure 6. — Depth distribution in percent of male and 

 female Acartia longiremis during the eclipse. 



restricted almost entirely to adult females. In 

 all of his samples, females of A. clausi were 

 concentrated in the upper layers and the males 

 at lower depths. 



BEHAVIOR OF THE GREEN CRAB 



Naylor (1958) observed that the rhythmic 

 activity of green crabs iCarcinus maenas) 

 could be divided into two components, one of 

 diurnal frequency with a peak at night, and the 

 other, a tidal frequency with a peak at high 

 tide. On the day of the eclipse, low tide oc- 

 curred an hour before totality and high tide 

 three hours after sunset; con.sequently the be- 

 havior of the crabs could be judged inde- 

 pendently of their response to tides. 



Thirty crabs, 15 of each sex, were u.sed as 

 test animals. The mean width was 62 mm. 

 (range, 42-79 mm.) for the males, and 60 mm. 

 (range. 51-69 mm.) for the females. The 

 males were banded so that the sexes could be 

 readily distinguished during the experiment. 

 The crabs were placed in a fiberglass tank 1.3 

 by 1.0 by 0.5 m. that had a 7 cm. layer of sand 

 and gravel on the bottom (fig. 7). One corner 

 of the tank was covered with fiberboard to 

 provide a darkened shelter. Running water 



264 



U.S. FISH AND WILDLIFE SERVICE 



