i68 DISCOVERY REPORTS 



krill were massed throughout the daylight hours. Our deep observations generally, however (Tables 27 



and 28), provide ample evidence that they are never so massed, least of all (Table 32) by day. 



The accumulated evidence then from all sources reveals a heavy surface or near-surface massing 

 of the krill, and that while its absolute vertical range may extend from the surface down to about 

 1000 m., in so far as it may be said to exist in concentrations dense enough to satisfy the needs of the 

 whales, it is confined, especially at night, to an extremely narrow surface zone, no thicker it seems 

 than some 5 or 10 m. By day, while some of it is on the surface, as both our eyes and nets so distinctly 

 tell us, some of it too, principally it seems the older animals, is perhaps scattered about in patches 

 chiefly at levels between 10 and 40 or 50 m. From this it would follow that the whales themselves 

 must be largely surface or near-surface feeders, and that whether they normally range far into deeper 

 water or not, it must be principally from the surface that these great animals gather the ample harvest 

 necessary for their growth and development. 



On the assumption that heavy concentrations of krill, ' such as would concern the whale more than 

 stray individuals', are found 'anywhere between the surface and 100 m. ', Laurie (1933) suggests that 

 the lower limit of a blue whale's normal vertical range, in so far at least as feeding is concerned, may 

 be 100 m. Even this estimate, however, again in so far as it concerns feeding alone, now seems 

 unnecessarily deep. 



Referring to the diving and underwater feeding of penguins, Roberts (19406) states that it is 

 improbable that either the Macaroni or Ringed Penguin, the latter a prodigious krill-eater, normally 

 goes deeper than 5 m. This again suggests a massing of the krill at the surface and that in so far as its 

 predators are concerned there is simply no need for them to go deep. 



In their study of the histological structure of cetacean lungs Haynes and Laurie (1937) find that 

 alveolar epithelium is absent in the krill-eating fin, humpback and southern right whales, and suggest 

 that the protection afforded by it is perhaps unnecessary to animals living in a dust-free environment. 

 ' It is at least remarkable ', they add, ' that the thin membrane of the capillary can be subjected to the 

 pressures involved in deep diving . . . without the protection of a lining of epithelium to minimize 

 the danger of rupture'. It would not, however, be so remarkable if deep diving were unnecessary. 



Further evidence of surface feeding by baleen whales has recently come to light from a remarkable 

 source. I quote from Chittleborough (1959 a) : ' On January 29, 1954, a member of a whaUng expedi- 

 tion threw into the Southern Ocean a dentifrice tin containing a message bearing his name and address. 

 The position of the vessel was then close to 64^° S., 92° E. On June 27, 1954, this tin and message 

 was recovered from the intestines of a humpback whale which was being processed at the land station 

 near Albany, Western Australia'. Since this obviously must have been a sealed tin it must have been 

 swallowed at the surface. Moreover, it must have been swallowed in the Antarctic since it was 

 released in a position well inside the krill-rich East Wind zone, from which it is virtually impossible 

 that it could have drifted north, unless perhaps it had chanced to get into the cold krill-carrying surface 

 stream that (p. 58, Fig. 4) flows north-westwards in this locality. 



An early, perhaps the earliest, account of surface feeding by baleen whales^ is recorded well over two 

 centuries ago by Dudley (1725), who on the authority of an experienced whaleman of his acquaintance, 

 tells how the North Atlantic right {Eubalaena glacialis) in still weather is seen ' skimming on the 

 Surface of the Water, to take in a Sort of reddish Spawn, or Brett, as some call it, that at some Times 

 will lie upon the top of the Water, for a Mile together'. Or to quote Collins (1886). 'They were all 

 Finbacks, so far as I could tell. Their movements were sluggish, as they "played" back and forth in 

 the tide rips, with their mouths open, the upper jaw just at the surface, scooping in " feed " '. Blue, fin, 

 humpback, right (several species), sei, Bryde's and minke whales have all been reported feeding on the 



1 See, however (p. 215), the remarks of Sagard-Theodat (1632). 



