. ADOLESCENTS AND ADULTS ALL STAGES —1 30 I T 1 I 1 O S 10 15 20 25 MEAN LENGTH (MM) Fig. 10. Variation of the mean length with depth of all stages and of adolescents and adults only taken in the N70V between 2000 hrs. and midnight. The numbers of specimens upon which the means are based are shown in brackets. and Gardiner (1932) showed that the reverse applied to Daphnia longispina O. F. Muller (1785) in Lough Derg. Motoda (1953), working at Lake Shikotsu in Japan, found that at midday the copepodites of Acanthodiaptomus yumanacensis (Brehm) were nearer to the surface than the adults. He also
. ADOLESCENTS AND ADULTS ALL STAGES —1 30 I T 1 I 1 O S 10 15 20 25 MEAN LENGTH (MM) Fig. 10. Variation of the mean length with depth of all stages and of adolescents and adults only taken in the N70V between 2000 hrs. and midnight. The numbers of specimens upon which the means are based are shown in brackets. and Gardiner (1932) showed that the reverse applied to Daphnia longispina O. F. Muller (1785) in Lough Derg. Motoda (1953), working at Lake Shikotsu in Japan, found that at midday the copepodites of Acanthodiaptomus yumanacensis (Brehm) were nearer to the surface than the adults. He also observed that the males of this species showed a greater sensitivity to light than the females. Gushing (1951) suggests that 'some animals become more sensitive to light as they grow older and others become less so'. In Fig. 10 the mean lengths of adolescents and adults taken by the N70V between 2000 hrs. and midnight on the Greenwich meridian, have been plotted against depth. We are only concerned here with the relative lengths at different depths, the actual lengths are dependent upon the time of year the hauls were made. There is little doubt that there is a definite tendency for the smaller individuals to inhabit the upper 100 m. during this period whereas the larger ones are found below this level. It does not follow that the larger animals are never found in the upper layers, for specimens of over 35 mm. have frequently been taken in the loo-o m. NiooB at night; nor does it mean that the
Size: 1679px × 2978px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
