134 DISCOVERY REPORTS 



reported^ from time to time with krill in their stomachs. Apart from their swallowing it fortuitously, 

 however, or as an occasional morsel, it is doubtful if these animals take it in any great quantity directly 

 from the sea. More likely they obtain it indirectly, as the Giant Petrel does, from the stomachs of the 

 larger quarry upon which they habitually prey. As adults they feed principally on fish or squid,^ the 

 Leopard seal, besides being partial to fish, being a voracious hunter of penguins as well. In view of its 

 partiality to krill-eating penguins and fish it would be surprising indeed if E. superba were not found 

 occasionally in the stomachs of this seal. Rustad (1930), however, does mention one instance where 

 the krill in the stomach of a Leopard were so fresh that they obviously must have been taken directly 

 from the sea 'and not merely passed in as stomach contents of the fishes', while more recently Mr L. 

 Catherall, who wintered at Hope Bay, North Graham Land with a Falkland Islands Dependencies 

 Survey party in 1956, reports^ a young Leopard with the stomach fully distended by 'completely 

 undigested ' krill. Other evidence that the young Leopard may be partial to, or even perhaps a sub- 

 stantial consumer of, E. superba comes from the private diary of Nicolai Hanson (1902) who died at 

 Cape Adare in 1899. Referring to a specimen shot in the pack earlier that year he remarks, 'It was 

 a fine young Leopard-Seal. Like the one Borchgrevink killed, his stomach was full of small shrimps *. 

 In general, however, as Bertram (1940) points out in his remarks on the diet of the adult Weddell, 

 it is obvious that the Crustacea found in the stomachs have ' been swallowed along with the fish that 

 had already devoured them'. The Weddell pups on the other hand do it seems feed for some time 

 directly upon the krill, Lindsey (1937), in his study of the Weddells of the Bay of Whales, having 

 shown there is a short transition period after weaning when the young seals subsist largely on 

 Crustacea before taking to the adult diet. ' The change from a milk diet ', he writes, ' is gradual com- 

 bining amphipod and isopod crustaceans with the milk for a time. The stomach of a 5 5 -day seal 

 contained milk and a few Euphausia superba and other crustaceans. Another pup. . .2 months old, 

 was filled with Euphausia'. Lindsey's pups, however, could not in fact have been eating E. superba 

 since this species it is now known (p. 124) does not extend, except for a very short distance, into the 

 shallow shelf water of the Ross Sea. In all probability they were feeding on E. crystallorophias, that 

 other large euphausian superficially resembling the krill, which swarms in great profusion in this 

 locality. The Crabeaters examined here by Lindsey (1938) and Perkins (1945) also it seems must have 

 been feeding on this species. Nevertheless, it may readily be inferred from Lindsey's observations 

 that in other parts of Antarctica where E. superba was the dominant swarming euphausian it would be 

 to this species among others that the Weddell pups would turn during their brief period of crustacean 

 feeding. It would appear too that the occasional adult Weddells that wander off on the pack also 

 take krill in some quantity from the sea, Barrett-Hamilton (1901a) in his account of the seals of the 

 ' Belgica ' expedition stating that the Weddells collected on the pack by Racovitza were feeding on 

 ' the Schizopod crustacean Euphausia '. He repeats this in the Antarctic Manual (Barrett-Hamilton, 

 1901^) and again (Barrett-Hamilton, 1902) in his account of the seals collected by Hanson in the 

 'Southern Cross', remarking that the Weddell, like the Crabeater, 'feeds when on the pack-ice, 

 according to Dr Racovitza, on Euphausia '. The toll of the krill exacted by the straying Weddell, 

 however, must be very small, negligible in fact when compared with the major ravages of whales, 



1 Wilton (1908); Pirie (1908); Bruce (1913); Tattersall (1918); Rustad (1930); Murphy (1936); Hamilton (1939); Allen 

 (1942). 



2 Wilson (1907a); Levick(i9i56); Matthews (1929a); Lindsey (1937); Hamilton (1939); Bertram (1940); Cendron (1952); 

 Stonehouse (1953) et al. Although krill-eating fish are probably mainly responsible for the presence oiE. superba in the stomachs 

 of these essentially carnivorous (or non-plankton) feeders, it may be noted that some species of squid (Brachi, 1953), many 

 more perhaps than we are aware of, also feed upon the krill. Bierman and Voous (1950) counted 100 Euphausia eyes (probably 

 E. superba) in the stomach of an Emperor penguin and in the stomach of another up to 124 cephalopod beaks. 



^ In a letter to Dr R. M. Laws formerly of the National Institute of Oceanography. 



I 



