HAPPENING OF THE WHALES UPON THE SWARMS 243 



light organs of his specimens that were glowing he must I think have had them before him in a dish. 

 Gunther it will be recalled (p. 153) also mentions them shining in the dark, but his specimens were in 

 contact with the deck of a vessel, not in their natural element. Wilton's observation on the other hand 

 clearly refers to a natural display. 'Many Euphausia', he writes, 'were frequently observed, and it 

 was noticed after dark that these caused a phosphorescence on the ice and in the water'. This was 

 recorded in 60° 10' S, 42° 35' W shortly after the 'Scotia' entered the pack-ice of the Weddell Sea. 

 A year later in the same waters, but much farther to the south and east, he records other instances of 

 night phosphorescence but gives no hint as to the cause. Some he describes as ' large blobs ' on the 

 surface about the size of a Royal Quarto page. Much in fact of Wilton's phosphorescence might have 

 been produced by organisms other than E. superba.^ The absence of night phosphorescence in 

 Antarctica is mentioned I see by Webster (1834), an early observer of natural phenomena in these 

 high latitudes of particular accuracy and diligence. He writes, ' At no time did I observe the least 

 tendency to scintillation in the waters of the southern parts; and, although the nights were very dark 

 when we left, the sea was not phosphorescent'. Carrington (i960) it is true has said that after dusk 

 the bright red euphausians so abundant in the colder parts of the southern seas ' cause the whole 

 surface of the ocean to glow with a ghostly radiance ', but he gives no authority for this. 



It is possible that the krill do not luminesce spontaneously, but perhaps only when agitated as, for 

 instance, when colliding violently with the deck of a ship or perhaps when in contact with ice. Clarke 

 and Breslau (i960) find that among certain Dinoflagellates, while spontaneous luminescent flashing 

 is rather weak, their flashing increases strongly on agitation. 



IMPACT OF THE WHALES ON THE SWARMS 

 Since they vary enormously in size, from some only a foot or two across to others as much as half 

 an acre or so in surface area, it is obvious that while in certain instances a whale could dispose of 

 an entire swarm at a single mouthful in others the demoHshing or gross depletion of a patch or local 

 accumulation of patches would be far from being such a catastrophic occurrence. In general, single 

 whales, or small groups of them, would by themselves no doubt take some considerable time to bring 

 about a serious local depletion among the swarms on which they fed and would, therefore, tend to 

 remain for some time in the area in which they were feeding. Large schools on the other hand, if 

 they kept together, would make shorter work of their prey and would, therefore, tend to keep on the 

 move more readily than the scattered whales. It is easy to imagine, for instance, the 100 or perhaps 

 200 whales Gunther describes feeding on p. 150 wreaking such wholesale devastation among the local 

 concentration of swarms on which they were centred that in a relatively short time they would be 

 compelled to move on to find, and continue their work of destruction in, fresh fields as yet perhaps 

 unravaged by their kind. Indeed it will be recalled Gunther 's foraging whales already seem to have 

 left their mark upon the swarms on which they preyed. 



And they do not, it seems, move by any means entirely at random, the results of whale-marking 

 distinctly suggesting that having wrought destruction, or at any rate gross depletion, in one area they 

 tend to move away towards richer, or shall we say as yet unravaged, fields against the main trend of the 

 surface stream that is carrying their food as it flows, o-group whales,^ for instance, marked near South 

 Georgia (Rayner, 1940), in a remarkably large number of instances have been killed in Weddell West, 

 suggesting that the foraging whales as they continue to feed move in the main against the surface 



^ Hodgson (1905), for instance, records that during the winter in McMurdo Sound 'hauling the tow-nets always provoked 

 a brilliant display of an emerald green phosphorescence, chiefly from the contained Copepods and Ostracods'. 

 2 Whales into which marks have been fired and recovered later in the same season. 



27-2 



