. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. ,o8 DISCOVERY REPORTS they did, before, concentrations of First Calyptopes confined exclusively to great depths will prove in the long run to be of just as common occurrence during the darkest as during the brightest hours of the day. It follows from the foregoing that any attempt to illustrate the diurnal vertical movements of the First Calyptopis, if it be based as in Fig. 8 (or as by Fraser in his Fig. 33) exclusively upon stations where deep Metanauplii are moulting, or any attempt whatsoeve
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. ,o8 DISCOVERY REPORTS they did, before, concentrations of First Calyptopes confined exclusively to great depths will prove in the long run to be of just as common occurrence during the darkest as during the brightest hours of the day. It follows from the foregoing that any attempt to illustrate the diurnal vertical movements of the First Calyptopis, if it be based as in Fig. 8 (or as by Fraser in his Fig. 33) exclusively upon stations where deep Metanauplii are moulting, or any attempt whatsoever that fails to take account of the I400-I800 IBOO-2200 2200-0200 O2O0-O60O 0600-IOOO IOOO-I400 0-1 SO 100 250- 500 750 lOOO-J. SOO 1000 0- C M - 298 286 361 ~ ^ C M 50- C M - 1305 373 20 _ _ C M 100- C M 12 6548 21 94 38 5 C M 250- C M 10 889 36 I50 32 31 C M C M 3 17 547 2318 23 69 282 3702 6 2! 1 17 C M 750- C M 15 146 2573 14 165 7 577 144 - C M Fig. 8. Pseudo-diurnal vertical migration. The four-hourly vertical distribution of the First Calyptopis based on the aggregate of the catch-figures shown in Fig.^6. disturbing influence of the deep moulting of the Metanauplius upon the results, must end up in a picture that in some respects is illusory. For such an illustration must inevitably include large numbers of larvae which, although to all appearances migrants into deep water from the surface, could never in fact have been anywhere near the surface at all. Fig. 8 in short provides a typical example of the many pitfalls oceanography falls heir to through the employment of nets that do not go deep enough. For if the lower limit of observation in this instance had been say 500 m. there would have been no reason to suppose that the orthodox pattern of rhythmic diurnal vertical migration it manifestly presents was anything other than real, or to doubt that the First Calyptopis made a daily descent into the warm south-flowing core of the deep current running counter to the surfac
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