THE 

 FALKLAND SPECIES OF THE CRUSTACEAN 



GENUS MUNIDA 



By G. W. Rayner, b.Sc 

 (Text-figs. 1-18) 



INTRODUCTION 



IN the course of a trawling survey of the continental shelf surrounding the Falkland 

 Islands and fringeing the Argentine Patagonian coast, carried out by the R.R.S. 

 'William Scoresby' during the months October 193 1 to April 1932, large numbers of 

 the Anomurans, Mimida subriigosa (White) and Miinida gregaria (Fabricius) were taken. 

 This survey was complementary to the trawling surveys previously carried out by the 

 same vessel at different seasons during the years 1927 and 1928. At the same time it was 

 more extensive, embracing as it did a much larger area and many more observations. 

 The two species of Mimida were met with far more frequently than on previous occasions 

 and at times in very much larger numbers. The great importance of these two species in 

 the bionomics of the area surveyed was still more fully realized, and although Matthews 

 was then publishing his report, "Lobster Krill, Anomuran Crustacea that are the food 

 of Whales" (Matthews, 1932), which dealt with the material from the two earlier 

 surveys together with certain taxonomical and historical aspects, it was thought that 

 the large amount of material being obtained would provide opportunity for further in- 

 vestigations on their respective life histories. 



Both species are of considerable economic significance on the grounds surveyed, and 

 they occur in certain areas in very great abundance. Matthews has shown that the free- 

 swimming post-larval form of M. gregaria, the so-called Grimothea, is of prime im- 

 portance as a food supply for the whalebone whales which are to be found in this area, 

 whilst Hamilton (1934) stresses the part played by Mimida in the diet of the southern 

 sea lion, Otaria byronia. Hake, Merluccius gayi, taken in the trawl, were frequently 

 found to be subsisting entirely on these creatures, and many birds eagerly feed upon 

 them. These two species of Munida fulfil in the economy of the Falkland Islands region 

 a role similar to, but wider than, that of krill, Euphausia superba, in South Georgian 

 waters. 



Munida were found to be excellent eating in the ships of the expedition, and they are 

 utilized as food in the small ports on the coasts of Chilean and Argentine Patagonia 

 under the wide term " Camerones." It is possible that in the future they may acquire 

 commercial importance, for more use could be made of them for human consumption. 



The existence of a pelagic post-larval form in M. gregaria is of considerable biological 

 interest, for, so far as we are aware, it occurs only in this one species of the genus Munida. 



