THE HUMPBACK WHALE 47 



These figures show the marked fatness of immature whales of both sexes and indicate 

 that a decrease in fatness takes place towards the end of the season both at South 

 Georgia and South Africa, but they do not help to give any reason for the great fatness 

 of the smaller whales. Immature whales of other species, Sei and to a lesser extent Fin 

 and Blue, show a similar, if not so striking, greater fatness than the adults. 



The curves in Fig. 47 also show the increased fatness of pregnant whales, with a 

 decrease towards the end of the South Georgia season. With those in Fig. 46 they 

 further show a lesser fatness for adult males and females, with a decrease in fatness 

 towards the end of the season in the former. It must be noted, however, that the 

 figures for South Georgia may differ from those that would be obtained from a longer 

 series of observations, because Humpbacks are only taken there by special permission 

 during the times of scarcity of other species of whale. 



PARASITES 



EXTERNAL 

 Humpback whales are notoriously infested with external parasites or semi-parasites ; 

 the following list shows those recorded from the present series : 



CRUSTACEA. PROTOZOA. 



CiRRlPEDlA. Haematophagus sp. 



Coromda sp. DIATOMS. 



Conchoderma sp. ' Cocconeis sp. 



Amphipoda. Licmophora. 



Paracyamtis sp. 



Of these perhaps only Paracyamtis is a true parasite, the other animals and plants 

 merely using the whale as a substratum. Of the Cirripedes Coronula was present in 

 larger or smaller numbers on all Humpbacks examined. This barnacle occurs in greatest 

 numbers on the knob under the chin, round the genital and anal apertures, and on the 

 knobs of the flippers and flukes. It occurs in lesser numbers on the ventral grooves, the 

 surface of the head, and scattered over the sides, but rarely on the dorsal surface of the 

 body. Characteristic circular scars with radiating lines in them mark the sites where 

 Coromda has formerly grown, and are commonly present in some numbers on Hump- 

 backs. Olsen (1914-15) makes the interesting observation that at Port Alexander during 

 the northward migration the Humpbacks are thickly infested with Coronula, but that 

 on the southward migration they are nearly all clean or infected with small barnacles 

 only. He suggests that the barnacles are killed by the fresher water off the Congo and 

 drop off, and in further illustration of this supposed phenomenon states that mariners 

 used to bring their ships into these waters to clear them of Cirripedes. 



Conchoderma is not quite so frequent on the Humpback as Coromda, and occurred 

 in 85 per cent of the whales examined. It nearly always grows only on the shells of 

 Coromda and not directly on the epidermis of the whale. The heaviness of Conchoderma 

 mfection varies from one or two individuals to thick clusters on the Coronula on all 

 parts of the body. 



