. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 2S0 DISCOVERY REPORTS The dominance of the adult female is particularly pronounced, for instance, at Station WS 915 where a full grown swarm consisting of stage 7 males and gravid females was encountered in the East Wind zone near Enderby Land in February 1936. The sample obtained consisted of 215 males and 531 females all of which were measured to the nearest millimetre. Their length frequencies in 2-mm. groups, plotted on a somewhat finer scale than has been used in Fig. 52, are shown in Fig.
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 2S0 DISCOVERY REPORTS The dominance of the adult female is particularly pronounced, for instance, at Station WS 915 where a full grown swarm consisting of stage 7 males and gravid females was encountered in the East Wind zone near Enderby Land in February 1936. The sample obtained consisted of 215 males and 531 females all of which were measured to the nearest millimetre. Their length frequencies in 2-mm. groups, plotted on a somewhat finer scale than has been used in Fig. 52, are shown in Fig. 53. SO-i 40 ;30- '20 10. â 100 SC^ 32 34 36 384042 44 46 48 SO 52 54 5658 60 62 64 66 LENGTH RANGE I 2 3 4 5 6 7 STAGE d* I 2 3 4 5 6 7 STAGE $ Fig. 53. Sexual dimorphism and developmental condition of the sexes in a fully adult swarm of E. superba, showing dominance of the female in a sample from St. WS 915. Developmental condition of the sexes In Table 19 of Bargmann's appendix it is repeatedly shown that, except in the very young mixed larval and adolescent swarms encountered from August to November, the dominant state of sexual development in the male is normally one or two stages, sometimes more, ahead of the corresponding state in the female. The advanced state of the male, as Figs. 50-2 show, persists throughout the greater part of the life of the swarm up to the point of pairing, when as might be expected swarms in which both males and females are dominantly at stage 7 are not uncommonly encountered. An ingenious device has recently been constructed by Vittorio and Livia TonoUi (1958) and used to study the form and internal structure of plankton patches in the Italian lakes. It could well, it seems, be employed with advantage in future studies of the biometrics of krill swarms, with especial reference perhaps to the larval swarms. A rather long plankton net ends in a polysthyrol tube that reaches the boat. The tube is here connected to a turbidi- meter, from which anot
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